MXPA01001708A - Process and catalyst for making dialkyl carbonates - Google Patents

Abstract

A process for producing dialkyl carbonates, such as dimethyl carbonate, from the reaction of a primary alcohol with urea in the presence of a novel catalyst which is a complex of organotin with a high boiling electron donor compound acting as solvent which are bidentate ligands which form 1:1 bidentate and/or 1:2 monodentate adducts with R'2SnX2 (X=C1, R'O, R'COO or R'COS), R'3SnX, R'2SnO, Ph3-nR'SnXn or Ph4-nSnXn (wherein R'=CqH2q-1 n=0, 1 or 2 and q=2 to 12) and mixtures thereof, such as materials having the general formula RO[CH2(CH2)kCH2O]mR, wherein each R is independently selected from C1-12 alkyl, alkaryl or aralkyl moieties, k=0, 1, 2 or 3 and m=1, 2, 3, 4 or 5.

Description

PROCESS AND CATALYST FOR PREPARING DIALKYL CARBONATES BACKGROUND OF THE INVENTION Field of the Invention The present invention relates to a process for the production of dialkyl carbonates, particularly dimethylium carbonate wherein the reaction occurs simultaneously to the separation of reactants and carbonate products. More particularly, the invention relates to a process in which the methanol is reacted with urea and / or alkyl carbamate in the presence of a novel catacytic complex consisting of a homogeneous organic compound of tin and a compound containing an oxygen donor of electrons. Related Technique Diakali carbonates are commercially important compounds, the most important of which is dimethyl carbonate (DMC). Dimethyl carbonate is used as a methylating and carbonizing agent. It can also be used as a solvent to replace halogenated solvents such as chlorobenzene. Although ei. The current price of dimetium carbonate is prohibitively expensive to use as a gasoline additive, it could be used as an oxygenator in refined gasoline and an octane component. Dimethyl carbonate has a content of oxygen (53%) much higher than MTBE (methyl tertiary butyl ether) or TAME (methyl tertiary amyl ether), and therefore, it does not have to have the same effect. It has a RON of 130 and is less volatile than MTBE or TAME. It has a pleasant smell and contrary to the ethers, it is biodegradable. In the oldest commercial processes, dimethylium carbonate was produced from methane! and phosgene. Due to the extreme toxicity and cost of phosgene. Due to the extreme toxicity and costs of phosgene, there has been an effort to develop better processes that are not phosgene based. In a new commercial process, dimethyl carbonate is produced from methane, carbon monoxide, molecular oxygen and copper chloride by oxidative carbonylation in a two-stage slurry process. Such a process is described in EP 0 460 735 A2. The main disadvantages of the process are the low production rate, high cost for the separation of products and reagents, formation of by-products, high recycling requirements and the need for reactors resistant to corrosion and processing lines. Another new process is described in EP 0 742 198 A2 and EP 0 505 374 Bl where dimethyl carbonate is produced by means of the formation of methyl nitrite instead of the copper methoxychioride mentioned above. The by-products are nitrogen oxides, carbon dioxide, metiiformate, etc. Dimethylium carbonate in the reactor product stream is separated by distillation by solvent extraction using dimethyium oxarate as the solvent to break the azeotropic mixture. Although the chemistry seems simple and the production rate is improved, the process is really very complicated due to the separation of multiple materials, the balance of materials in several sections of process fiow, complicated process control and having to handle the dangerous chemical substance methyl nitrite. In another commercial process, dimethyl carbonate is produced from methanol and carbon dioxide in a two-stage process. In the first stage, cyclic carbonates are produced by reacting the epoxides with carbon dioxide as described in U.S. Patents. 4,786,741; 4,851.55 and 4,400,559. In the second step dimethylium carbonate is produced together with giicoi by means of exchange reaction of cyclic carbonates with methane !. See for example Y. O ada, et ai. "Dimetyi CarPonate Porductión tor Fue! Additives", ACS, Div. Fuel Chem.,. Preprint, 41 (3), 868, 1996, and John F. Knifton, et al. "Ethyiene Giycoi-Dimethyi Carbonate Cogeneration", Journal of Molecular Chemistry, vol. 67, pgs. 389-399, 1991. Although the process has its advantages, the reaction rate of epoxides with carbon dioxide is low and requires high pressures. In addition to the exchange reaction of cyclic carbonate with methane! it is limited by equilibrium and methane! and the dimethyium carbonate form an azeotrope making separation difficult. It is known that diacyl carbons can be prepared by reacting aiiphatic alcohols such as methane! with urea in the presence of several heterogeneous and homogeneous catalysts such as dibuti-stannous dimethoxide, tetraphenyltin, etc. See for example P. Bal! et ai. "Synthesis of Carbonates and Poiycarbonates by Reaction of Urea with Hdroxy Compounds", Cl. Mol. Chem., Voi i, pgs. 95-108, 1984.. Ammonia is a by-product and can be recited to urea as in the next reaction sequence. 2í Or¡ -t H- tí- C-KH- > - = »- ^ 3- -gp 1- \? -? • A. C .I. £ A. * LÍGÍ -: C? ÜbúiiñL O of dl alcf? Ii HH-, C «H rf - C-MH- - H-, 0 -rea The carbamates are produced at a lower temperature followed by the production of diacyl carbonates at higher ammonia temperatures, producing ammonia in both stages.

O í H? T! - 'w -Nin OH. ==, 4. R? -c-íJH3 - NH-, caiibaiuat-ü of alkyl ii RO-C-NK- izbcmato ue di lquile As noted above, the two reactions are reversible under the reaction conditions. In order that the catalytic activity of the organotin compounds is R-Sn < R.SnX < < R_SnX :, where X = Ci, RO, 1 5 RCOO, RCOS. A maximum reaction rate and minimal by-product formation are reported for diazo tin (IV) compounds. For most catalysts (Lewis acids), greater catalytic activity is required if the reaction is carried out in the presence of a An appropriate cocataiizador (base of Lewis). For example, the preferred cocatalyst for the organic tin (IV) catalyst such as dibutyltin dimethoxide, dibutyltin oxide, etc. are triphenyphosphine and 4-dimethyia inopyridine. However, the decomposition Z Ü thermal intermediate carbamates to isocyanic acid (HNCO) or isocyanuric acid ((HNCO) 3) and alcohols are also provided by means of the organotin compounds tai such as dibuti-stannous dimethoxide or dibuti-tin oxide used in the synthesis of the aiiphatic carbamates. W095 / 1736S describes a process for producing diachiium carbonate tai as dimethyium carbonate in two steps from alcohols and urea, using the chemistry and catalysts published by P. Bail et al. In the first step, the alcohol is reacted with urea to produce an alkyl carbamate. In the second step, diacyl carbonate is produced by reacting the alkyl carbamate with alcohol at higher temperatures than in the first stage. The reactions are carried out using an autoclave reactor. However, when methane! it is reacted with methyl carbamate or urea, the N-alkyl byproducts such as N-methyl methyl carbamate (N-MMC) and N-aiquii urea are also produced. Diacylium carbonate is present in the reactor in an amount between 1 to 3% by weight based on carbamate tota! and the alcohol content of the reactor solution. SUMMARY OF THE INVENTION Diakali carbonates are prepared by reacting the alcohols with urea or alkyl carbamate or both in the presence of an organic complex of the IVA (IV) group as a complex of dibutyltin dimethoxide in where the reaction is preferably carried out in a heat exchanger of a distiller with the concurrent distillation of the diacylium carbonate. In a preferred embodiment, the interacting agents are high-boiling organic electron donor compounds having one, two, three, four or more oxygen atoms per molecule, preferably two or more oxygen atoms per molecule, preferably polyethylene ethers as triglyceride (dimethyl triethylene glycol ether), whose boiling point is preferably higher than methane! or dimethyium carbonate and which serves both as a cocatalyst and solvent. Thus the present invention provides a process for improving the concurrent distillation of diakaryl carbonate from the reaction concurrently with the reaction and preferably using specific binding agents to catalyze the organotin. Preferred compounds containing electron donating oxygen atoms useful as a cocatalyst and / or solvent consist of bidentate binders that form 1: 1 bidentate adducts and / or monodentates 1: 2 with R 'SnX (X = C1, R'O, R'COO or R'COS), R'.SnX, R '_, SnO, Ph.R'SnX or Ph ,.

SnX (where R '= C H. N = u, l or 2 and q = l a 12) and mixtures of them. In addition, these materials can be mixed with higher hydrocarbons, preferably having 8 to 12 carbon atoms, such as dodecanes and xylenes. Examples of binders that form bidentate adducts 1: 1 and / or monodentates 1: 2 with R 'SnX2 include diethylene glycol ether, 1,3-dimethoxy propane, i, 2-dimethoxypropane, dipropylene ether glycol dimethylium, 1.4. dioxane, di-n-butyl ether and the like. An advantage of producing dimetium carbonate from urea and methane! is the separation of dimethyl carbonate for the reaction mixture. Since the water is not co-produced, the reaction mixture (the superior product) does not form a ternary azotrope, then the separation of the dimethyl carbonate product from the superior mixture is easier than the current commercial processes that have to deal with such azeotrope. ternary. BRIEF DESCRIPTION OF THE DRAWINGS Figure i is a diagram of an apparatus that can be used to perform the present invention. Figure 2 is a graph of the upper dimethyl carbonate vs. hours in the current comparing methane! soio with methane! + trigiimo. Figure 3 is a graph of the upper dimethyl carbonate vs. hours in the current comparing methane! soio with methane! + trigiimo and methane! + trigiimo + DMAP at a higher speed of cc / min. Figure 4 is a graph of methylamine in ia top vs hours in streams comparing soio methane! with methane! + trigiimo and methane! + trigiimo + DMAP at a speed higher than 1.5 cc / min. Figure 5 is a graph of upper dimetium carbonate vs hours in streams comparing soio methane! with methane! + trigiimo at a higher speed of 2.7 cc / min. Figure 6 is a graph of upper dimethyl carbonate vs. hours in the stream for a process of a single stage. DETAILED DESCRIPTION OF THE INVENTION The invention is preferably carried out in the presence of a solvent containing electron donor with high boiling point that also serves as a compounding agent with the organotin compound, by using the heat exchanger of a distiller as reactor. The temperature of the reactor is controlled by changing the top pressure of the distillation column. The use of the heat exchanger and the distillation column allows the effective removal of the reaction products, dimethyl carbonate and ammonia, keeping the catalyst homogeneous and the solvent in the reactor. The column may have any conventional form such as trays, packages or combinations thereof. The compost of organotin catalyst Novelty can be prepared by mixing an organotin compound with high boiling point electron donor containing oxygen compounds, such as ethers, generally at room temperature, in situ in the reaction zone, for example the heat exchanger at the start of the reaction. Diacylium carbonate reaction. When hairs, acetates, or organotin oxides are used as catalytic precursors, complex formation can be carried out prior to the initiation of diacylium carbonate in order to remove the acid or water, which is generated in the complex reaction, although not it is necessary or preferred to do so since the acid component and the water are easily removed from the upper part during the start of the reaction of the carbonate and diary. The reaction order of the 2-methyloxycarbamate in the presence of excess 2-ethylhexium alcohol has been proposed as pseudo first order or less. Therefore, a methane concentration! lower in relation to a given concentration of methyl carbamate is expected to be favorable for a higher conversion rate of the methyl carbamate. The use of the heat exchanger and the distillation column, and the high-boiling oxygen atoms containing the solvent, such as the di-thiimo (diethylene glycol dimethyl ether), triglyceride (ether di-triethylene glycol dimethylium) and tetrahydroxy (triethieno giicoi dimetii ether) or tetragli or (tetraethylene glycol dimethyl ether), etc. it allows to carry out the reaction under any desired pressure while maintaining any desired concentration of reactants (methane!, urea and carbamate) and product (dimethyl carbonate) in the reaction zone to obtain the best economic results. In selecting the high boiling ether solvent, the diaryl carbonate produced in the reaction is considered. For example, triethylene dimethyl ether is preferred for the production of dimethyl carbonate, but it is not preferred for diethyl carbonate production, because the product is contaminated with methyl ethyl carbonate and the solvent is slowly converted to triethylene ether. diethyl A preferred solvent for the production of diethium carbonate would be tri- or tetraetiieno giicoi dietiio ether. In the present invention, the desired ratio of the solvent to the methanol in the reaction medium is controlled by changing the proportion of methane! a high boiling point electron donor solvent having a given carbamate concentration or a given combined concentration of urea and carbamate in the heat exchanger. The use of electron donor solvent as trigi as a cocatalyst as well as part of the medium of The reaction overcomes the disadvantages of the previous processes. Despite the high yield or selectivity of the carbonates claimed in WO 95/17369 and P. Ball et al. (C: Mol.Chem., 95, 1984 and ACS Dvi. Of Poiymer Chemistry, Poiymer Preprints, 25, 272, m 1984 and C: Mol.Chem., 1994, vol.1, pp. 95-108) is important understand the decomposition of urea and carbamate. Urea can be thermally or catalytically decomposed to isocyanic acid and ammonium isocyanate or biuret (NNCONHCONH under the reaction conditions employed to prepare diacyium carbonates (D.JH. Beison et al., Chemical Soc. Reviess, 11, 41-56, 1982) Analysis of the upper ejected gas taken during the reaction indicates that there is some carbon dioxide produced Although P. Baii et al. Claim that the aiiphatic carbamates can be distilled without decomposition, the carbamates can also be thermally or catalytically decomposed to isocyanic acid. or isocyanic and alcohol JJ Godfrey, US Patent No. 3,314,754) or formaraiophanates (ROCONHCONH; HW Biohm and The Becker, Chem. Rev., 1952, 51, 471 ... Ball et al. stated that the thermal decomposition of carbamates in acid Isocyanic acid and alcohol have to do with carbonate formation, however, the document claims that this decomposition does not occur in the presence of cocatalyst. s suitable for some catalysts. Trifenilfosfina and 4-dimethiaminopyridine are cited as good cocatazers for organotin catalysts. The present examples 4A and 4B indicate that methyl carmabate decomposes thermally or catalytically in the presence of organotin catalysts. Dimethium carbonate is a highly effective compound so to improve the selectivity of dimethyl carbonate, the concentration of dimethyl carbonate in the heat exchanger should be kept as low as possible. In the present invention, a very low concentration of dimethyl carbonate is obtained by selecting the appropriate high boiling point solvent and controlling the top pressure which is a function of the proportion of methane! a high-boiling electron donor solvent in the heat exchanger with a single concentration given to methyl carbamate or the given combination of methyl carbamate and urea. The use of high-boiling electron donor compounds as catalysts and solvents improves the rate of formation of diacylium carbonates (due to the effective removal of ammonia and dimethyl carbonate from the reaction zone) and this at the same time prevents the formation of by-products such as carbamate N-aiquii alkyl, alkyl amine and N-aiquii urea or decomposition of urea or carbamate at a concentration relatively high diacyl carbonate in the reactor and the superior products. The high concentration of diacyl carbonate in the superior product reduces the cost of separation of the dianate carbonate from methane! for recycling. Since the reaction can be carried out at relatively low pressures (less than 100 psig), the new process has several advantages; lower cost for the construction material, better inventory cost of the catalyst, easy removal of ammonia and dimethyl carbonate products and ease of control of the optimum methane concentration! in the reactor for the speed of the formation of dimethyium carbonate maximum and selectively to dimethyium carbonate. The rinsing of the reactor (heat exchanger) with an inert gas such as nitrogen, although not necessary, can be included as a starting part. If inert gas is used to rinse the heat exchanger, the best pressures preferentially used in the present reaction system allows the use of a blower instead of a compressor for the inert gas. The preferred temperature range is 132-204.4 ° C, preferably 149-211. The preferred upper pressure is in the range 10-250psig, more preferably between 20-200 psig and more preferably between 25-150 psig. The desirable weight ratio of electron donor solvent with high pumping boiling point to methane! in the reactor is 100-0.01: 1, preferably 5-0.1: 1. The preferred concentration of the organotin compounds in the reactor is 0.5 to 40% by weight, preferably 2-30% by weight based on the total content in the reactor. The rate of the preferred top product is controlled to have 4-25% by weight. The preferred concentration of methyl carbamate or the combined concentration of methyl carbamate and urea in the reactor is 5-60% by weight, preferably 15-55% by weight during continuous operation. For the continuous production of dimethyl carbonate the urea solution can be pumped directly into the reactor or partially or completely converted to methyl carbamate before being pumped into the reactor. That conversion must be achieved in a pre-warmer or in a separate reactor. The solvent for the urea solution can be methane! Substantially pure or dimethyl carbonate solution very diluted in methane !. An example of the dilute carbonate solution diluted (Approximately 2% of dimethyl carbonate in methane!) is the current recirculated in the upper part of a dimethylium carbonate recovery column. In a whole or a portion of urea urea can be fed to ia D distillation column instead of the heat exchanger to partially convert the urea to the methyl carbamate before entering the heat exchanger. In another embodiment, the heat exchanger material may be added to the distillation column with the urea feed stream or at some other point along the column. Referring now to Figure 1 is a schematic representation of the experimental apparatus used for the above examples. The 350 ml heat exchanger 10 of the distiller equipped with a stirring paddle 12 was used as a reactor. The distillation column 3/4"diameter 20 was packed with ceramic bubbles of i / 8". The reagents, the solvent and the catalyst were charged to the upper heat exchanger at room temperature. (~ 24 ° C). The reactions were carried out by raising the temperature of the heat exchanger to a selected temperature by controlling the top pressure of the column. During the reaction the reactants were pumped into the heat exchanger continuously. The reaction products were removed from the heat exchanger as the upper product of column 20 by means of the fiow line 20 and condensed in the condenser 40 in which the ammonia was removed as steam by means of the line of fiow 50 and the product dimethyl carbonate was removed by medium of a flow line 60. During the reaction, the liquid volume of the heat exchanger remained at a constant level preferred to pump methane! additional, solvent methanol mixture or the solutions of urea or methyl carbamate in methanol or the solvent-methane mixture! and through the fio line 70. As an option a portion of the urea can be fed directly to the distillation column by means of the fiow line 90 as shown. In a similar manner, the catalytic converter of the heat exchanger 10 can be fed directly to the distillation column by means of the line of fiow 100. The samples for the analysis were removed from the heat exchanger by means of the line of fiow 80. samples of the upper (total) parts and the lower parts were analyzed by means of gas chromatography. The temperature of the mixer exchanger was controlled by controlling the upper pressure. To raise the temperature, the upper temperature rose. When the solvent containing oxygen atoms was used, with a high boiling point, the novel organotin catalyst was formed by mixing dibutyl tin dimethoxide and the solvent tai as triglycerides together in the heat exchanger. The reaction system in the reactor can be characterized as homogeneous.

THE EXAMPLE The distiller's top heat exchanger was charged with 96 g of urea, 112 g of methane, 113 g of triglyceride (triethylene glycol dimethyl ether) and 25.5 g of catalyst (dibutyltin aethoxide) in the heat exchanger and then raise The temperature of the heat exchanger up to the desired temperature with stirring. During heating and reaction, 5 percent by weight of the triglyceride solution in methane! It is continuously pumped in the heat exchanger to keep the liquid level constant in the heat exchanger. The temperatures of the heat exchange during the reaction were maintained by controlling the upper pressure. When the temperature of the kettle reached the desired temperature (160 ° C) the extraction of the upper liquid product started at a rate of i cc / m through line 60. At the beginning of the reaction, the temperature of the heat exchanger remained stable. at 160 ° C for one hour and then at 179.6 ° C until the inactivation.Pressures above 160 ° C and 179.6 ° C at the start were 100.6 and 106.5 psig, respectively.The column temperatures were 162.7 ° C in the bottom of the column and 122.7 ° C in the upper section of the column at 179.6 ° C temperature in the heat exchanger at the beginning of the reaction.The upper pressure reflowed as the temperature increased. conversion of urea to methyl carbamate. At the end (6 hours in the current) of the run, the upper pressure was 68.1 psig. The temperature of the column was 146 ° C in the lower section of the column and 112 ° C in the upper section of the column. The superior liquid products were composed of methane! and dimethyium carbonate with a small amount of ammonia dissolved. Trigium was not observed in the superior products. The change in the composition of the upper liquid products during the run is illustrated in Figure 2. While the sample of bottom product was taken at the end of the 6-hour run, it contained 7.2% dimethyl carbonate and 22.6% carbamate. of methyl, the top product contained 16.0% dimethyl carbonate. The content of urea in the bottoms of the proauct sample was unknown because the urea could not be analyzed by means of gas chromatography due to the decomposition of urea. EXAMPLE IB The reaction was carried out in an identical manner to Example 1A without the cocatalyst. The exchange was carried out with 96 g of urea, 2300 g of methane! and 50.1 g of dimethystatin dimethoxide. The temperatures of the heat exchanger during the reaction were maintained by controlling the upper pressure. The rate of discharge of the upper liquidation pro- duct was 1 cc / min. To maintain a constant liquid level in the heat exchanger during the run, the methane! Pure is pumped into the heat exchanger. At the beginning of the reaction, the temperature of the exchanger was maintained at 160 ° C for one hour and then at 185 ° C at the start were 163 and 261 psig. The temperature of the column was 162 ° C in the bottom section of the column and 163 ° C in the upper section of the column at the beginning of the heat exchanger temperature of 185 ° C. The pressure rose as the temperature advanced to maintain a temperature of 185 ° C. At the end (7.1 hours in the current) of the run, the upper pressure was 357 psig. The temperature of the column was 172.2 ° C in the bottom section of the column and 162.7 ° C in the upper section of the column. The change in the composition of the upper liquid products during the run is illustrated in Figure 2. While the sample of bottom product taken at the end of the run to 7.1 years contained 7.8% dimethylium carbonate and 2.2% carbamate. methyl, the upper product contained 1.5-dimethylium carbonate. The content of urea in the sample of the bottom product was unknown because urea can not be analyzed by means of gas chromatography due to the decomposition of urea. Example 1A shows how effective the carbonate product is removed from the reaction zone in ia present invention as shown in Figure 2. When the reaction is carried out in accordance with the preferred embodiment of the present invention from urea, the content of dimethyl carbonate in the product in the upper part increases rapidly as urea it is converted to methyl carbamate which in turn is converted to dimethyium carbonate. Due to the relatively low pressure of the distiller, the dimethyl carbonate of the product is effectively removed as the upper product of the lower heat exchanger as indicated by the concentration of dimethyl carbonate in the upper and bottom products at the end of the run; more dimethyl carbonate (16%) in the superior product than in the inferior product (7.2%). The sample taken from the heat exchanger contained 22.6% methyl carbamate. Urea is effectively converted to dimethyl carbonate with little indication of the decomposition of urea and methyl carbamate. When the reaction is carried out without the triglyceride as in Example IB, less carbonate and dimethy product is removed as a higher product as shown in Figure 23. Dimethyl carbonate accumulates in the lower heat exchanger or effective recycling medium. of the column under higher pressure than that which is removed as a top mixture. The superior product at the end of the current year contains 1.5% of carbonate of endetium, which compares with 7.8% of the total. z dimethyl carbonate in the lower product. The undesired side reactions of the dimetium carbonate product and the decomposition of urea and the carbamate occur due to the accumulation of DMC in the heat exchanger and the absence of cocaine taker which at the end of the run is 2.2% carbamate. methyl and 7.8% dimethyl carbonate in the heat exchanger. EXAMPLE 2 CATALYTIC COMPLEX When the dibuty-stannous dimethoxide (liquid at room temperature) was mixed with methane, ethyl ether or toluene, the dibutystane dimethoxide catalyst is completely soluble in these solvents and detected by means of gas chromatography if The solutions analyzed using the TCD detector and the DB-5 gas chromatography column. Dibutystane dimethoxide in the methanol solution or toluene was detectable (5.38 minutes retention time) by means of gas chromatography, and the analysis of the dibutyltin dimethoxide solution in diethyl ether indicated that the organotin compound in the solution was already present. dibuti-stannous dimethoxide The tin compound in the solution was much heavier than the dibuty-tin dimethoxide of that form which the peak of the new organotin complex in the solution had a retention time approximately 3 times longer (15.68 minutes). When the dibuti-stannous dimethoxide was mixed with the mixtures of triglyceride and methane! or pure triglyceride (CH20CH2CH20CHCH OCH: CHOCH.,) at room temperature, a precooked white foam was formed which settled slowly on the bottom of the bottles. If the white precipitate suspended in the solution was immediately filtered and the clear filtrate analyzed with gas chromatography, the organotin compound could still be detected, although the concentration was lower than expected. With the low concentration of organotin catalyst (1% by weight) in the mixed solution, the white precipitate dissolved completely to become a clear solution upon standing at room temperature overnight. If the suspension with the white precipitate is heated, the white precipitate is immediately solubilized. When these clear solutions were analyzed with gas chromatography, dimethystatin dimethoxide could no longer be detected. EXAMPLE 3A The distiller's heat exchanger was charged -with 125 g of methyl carbamate, luug methane !, iOOg of trigiimo and 24.7 g of dibuti-stannous dimethoxide. The temperature of the exchanger was maintained at 355-363 ° G ai controlling the upper temperature. The rate of aei fiow Z upper liquid product was adjusted to 1.5 cc / min. To maintain a constant liquid level in the heat exchanger, a mixture of methane and trigiimo was prepared by mixing 1650 g of methane with 142.5 g of triglycerum continuously pumped into the heat exchanger. The reaction mixture was carried out for 6 hours each day for 2 days, for a total of 12 hours. After a 6-hour run, the unit was deactivated. The next day the unit was restarted. During the reaction the superior liquid products were collected in a tank. At the end of the run all the upper liquid products composed in the tank and the inventory materials in the heat exchanger and the column were removed from the system and weighed and then analyzed. The samples taken during the run for the analysis were weighed. The result of this experiment is listed in table i. The change in the dimethylium carbonate and methylamine compositions in the higher liquid products during the run is illustrated in FIGS. 3 and 4 respectively. The pressures above 179 ° C at the beginning and the end were 53.4 psig and 139 psi, respectively. The temperatures of the column in the upper and lower section of the column were 2 ° C and 93 ° C at the beginning, and 142 ° C and 136 ° C at the end of the 12-hour run. The analysis of the bottom sample taken from the heat intercalator at the end of the run of 12 hours at the end of the 12-hour run indicated 0.1% ammonia, 4.1% dimethyl carbonate, 0.3% N-MMC, 2.7% methyl carbamate. 32.6% methane and 60.2 trigiimo. The upper product contained 6-9 dimetium carbonate. The content of urea in the sample of background product was unknown because urea could not be analyzed by means of gas chromatography due to the decomposition of urea. Example 3A demonstrates the superior performance and selectivity of the dimetium carbonate of the present invention compared to the prior art. The content of dimethyl carbonate in the upper liquid product of the present invention was at least 3 times higher than the dimethyl peroxide sodium (example 3B). Consequently, the separation of dimethyl carbonate from the superior product can be achieved at a much lower cost and a much smaller amount of material recess. When only methane is used as a solvent (Example 3B), the increase in the upper liquid product slowly improves the selectivity of the dimethylium carbonate and reduces the formation of undesirable by-products such as N-MMC.

N-methyl methyl carbamate) and methylamine, however, the amount of the undesired byproducts is still about 10 times greater than the preferred embodiment of the present invention. The increase in the product rate The higher cocatalyst ratio has little effect on the selectivity of dimethylammonium carbonate. The increase in the higher rate simply dilutes the concentration of dimethyl carbonate in the upper product stream. The superior products of the present invention generally do not contain methylamine or when much residual amounts. EXAMPLE 3B The reaction was carried out using the distiller. The run was performed identically to example 3A but without the cocatalyst. The heat exchanger was charged with 125 g of methyl carbamate, 200 g of methanoi and 25.3 g of dibuti-stannous dimethoxide. The rate of fiow of the superior product was fixed at 1.55 cc / m. The methane was continuously pumped into the heat exchanger to maintain a constant liquid level in the heat exchanger. The result is listed in table i. The charge in the compositions of dimethylium carbonate and methylamine in the higher liquid products during the run is illustrated in FIGS. 3 and 4, respectively. The pressures above 179 ° C at the beginning and at the end were 268.4 and 374.4 psig respectively. The temperatures of the column in the lower and upper section of the column were 167 ° C and 166 ° C at the start and 178 ° C and 176 ° C at the end of the 12-hour run. The analysis of the sample of bottom product taken from the heat exchanger at the end of 12 hours indicated ammonia traces, 6.9% dimetium carbonate, 3.6% N-MMC, 2.1% methyl carbamate, 86.6 methane and 0.7% others. The upper product contained 2.1% dimethyl carbonate and 2.5% methylamine. The content of urea in the sample of background product was unknown because urea can not be analyzed by means of gas chromatography due to the decomposition of urea. EXAMPLE 3C The thimerium was used as a solvent to distill the dimethyl carbonate product from the reaction zone, and the reaction was carried out using the distillation tank. The experiment was performed in an identical manner to Example 3A. The exchanged caior was charged with 125 mg of methyl carbamate, iOOg of methanoi, 21 g of cocatalyst of 4-dimethiaminopyridine (DMAP), 79 g of triglyme and 24.4 g of dibuti-stannous dimethoxide. The run was continued for 12 hours without interruption. To maintain a constant liquid level in the heat exchanger, a mixture of methane and trigiimo was prepared by mixing 1650 g of methane with 142.5 g of triglyceride continuously in the heat exchanger. The result is listed in Table 1. The change in the compositions of methyl carbonate and methylamine in the liquid products z or higher during the run are illustrated in Figures 3 and 4, respectively. The temperature of the heat exchanger was maintained at 173-181 ° C when controlling the upper pressure. The pressures above 179 ° C at the beginning and at the end were 58.9 and 81 psig, respectively. The temperatures of the column in the upper and lower section of the column were 114 ° C to 108 ° C at the start and 124 ° C and 118 ° C at the end of the 12-hour run, respectively. The analysis of the product sample of the heat exchanger at the end of the 12-hour run indicated 0.2 dimetium carbonate, 4.2% N-MMC, 0.5 methyl carbamate, 16.5% methane, 7.0% 4- dimetiiaminopiridina, 69.3% of trigiimo and 0.3% of others. The upper product contained 1.4% dimethylammonium carbonate and 0.2% methylamine. The concentration of urea in the sample of background product was unknown but it is expected to be very low.

Table 1 Example 3A 3B 3C Solvent 100 200 100 MeOH-79TG MeOH-100 MeOH 21 DMPA Heat Int. TG Temp. ° C 355 355 355 P. sup. initial psig 53.4 268.4 58.9 final 139 374.4 81 ll) Vei. cc / min i .5 1.5 1.5 Mass balance% 103. 1 105.7 89.9 Molar balance, r% 94.0 41.0 17.4 Apparent MC, conv.ml 95.4 93.2 98.9 Apparent selectivities, m% 90.2 31.8 9.7 DMC 0.6 8.9 6.8 DMC removed as 99.2 23.2 13.6 upper product, g ~ * The content of urea in the lower heat exchanger was not included in the calculation. TG: trigiimo, DMAP: 4- dimetiaminopyridine. In Example 3C, 4-dimethylaminiopyridine (DMPA) was used as cocatalyst as described in Ci Moi.

Chem., 1984, voi. i, 95-108, Baii et al. "Synthesis of carbonates and Poiycarbonates by reactions of Urea with Hydroxy Compound". In addition, it was used to perform the reaction under reduced pressure according to the present invention. Since DMAP is a Lewis base stronger than the triglyceride, the effect of the triglyceride on the catalyst as a cocatalyst is minimal. As shown in Table 1 and Figure 3, the organotin composite compounding cocatalyst which is the adduct (BU.Sn [OCH.j_ .xDMAP, where x = lo 2 or both), has a selectivity very low for dimetium carbonate. The analyzes of the upper vapor samples taken during the run confirmed the decomposition of the methyl carbamate, because the gas samples contained very large volumes of carbon dioxide. In Example 3C the analysis of the upper liquid product and the lower product taken at the end of the 12 hours indicated that the dimethyl carbonate was effectively removed from the reaction zone due to the decomposition of dimethyium in the upper product was 7 times greater than the background product. The formation of the unwanted by-product (N-MMC and methylamine) was much greater than in Example 3A, but somewhat better than Example 3B, probably due to the effective removal of dimethylammonium carbonate and ammonia during the run. EXAMPLE 4A COMPARISON The thermal decomposition of the methyl carbamate was carried out. A solution of methyl carbamate (12.3 weight percent) was prepared by dissolving 35 g of methyl carbamate in 250 g of triglycerin in a 350 ml round flask which was equipped with reflux column. The solution was refluxed with stirring at 170 to 180 ° C. After 12.45 hours of reaction, the solution contained 8.2% methyl carmate and 0.9 methane, indicating the thermal decomposition of methyl carbamate. The color of the solution changed from clear as water at the beginning to a clear golden yellow solution, indicating the formation of heavier compounds and a very small amount of white solid was deposited at the bottom of the condenser. EXAMPLE 4B COMPARISON The catalytic decomposition of the methyl carbamate was carried out using the same values of the equipment as in example 4A. A solution of methyl carbamate (11.9 weight percent) in trigiimeti was prepared by dissolving 35 g of methyl carbamate in 250 g of triglycerol and then adding 10 g of dibutyltin dimethoxide to the solution.

After 4 hours of reaction at 156 to 160 ° C, the solution contained 7.6 weight percent of methyl carbamate, 0.4 percent in weight of methane and 0.8 weight percent. of dimethyl carbonate, indicating the fastest decomposition rate catalyzed by the dibuty-stannous-trigiimethyl dimethoxide complex. The solution was changed from clear as water at the beginning to light orange and some solid was deposited on the bottom of the condenser indicating again the formation of heavier materials that could not be detected with gas chromatography. After 12 hours of reaction the solution contained 2.7 weight percent of methyl carbamate, 1.2 weight percent of methane and 2.7% of dimethylammonium carbonate. The visual examination indicated that the amount of solid white material deposited in the bottom of the reflux column increased slightly compared to Example 4A. EXAMPLE 5A The experiment was carried out in the same way in Example 3A. The exchange of calcium in the distiller was charged with 125 g of caroamate and methyl, iOOg of methane, 100 g of triglycerum and 25.0 g of dibuti-tin dimethoxide. The temperature of the intercalated air was kept at 122-180 ° C in order to control the higher pressure during the reaction.

The rate of fiow of the upper liquid product was fixed at 2.5 cc / min. A solution of methyl carbamate prepared to dissolve, 120 g of methyl carbamate in a mixed solution of 1960 methane and 40 g of triglyceride was pumped. in the heat exchanger to maintain the constant liquid level in the heat exchanger. The reaction ended after 12 hours in the current. The result of this experiment is listed in Table 2. The upper pressures at the beginning and at the end were 39.4 psig and 123.9 psig, respectively. The temperatures of the column in the upper and lower section of the column were 107 and 99 ° C at the beginning and 139 and 133 ° C at the end of the 12-hour run. The analysis of the sample taken from the heat exchanger at the end of the run indicated 0.2% ammonia, 14.8 & methane, 3.3% dimethyl carbonate, 22.4% methyl carbamate, 58.4% 'trigiimo and 0.9 & N-MMC. The upper product contained 9.0% dimethyl carbonate. The urea content in the sample was unknown because urea could not be analyzed by means of gas chromatography due to the decomposition of urea. EXAMPLE 5B The experiment was carried out in the same way as example 5a but without cocatalyst. The caior exchanger was charged with 125 g of methyl carbamate, 200 g of methanoi and 24.6 s of dibuti-stannous dimethoxide. The temperature of the heat exchanger was maintained at 178-180 CC ai controlling the upper pressure during the reaction. The rate of fiow of the upper liquid product is set at 2.5 cc / min. A solution of methyl carbamate prepared to dissolve 125 g of methyl carbamate in 200 g of methane, it is pumped into the heat exchanger to maintain • the constant liquid level in the exchanger. The reaction was terminated after 12 hours in the stream. The upper pressures at the beginning and at the end were 207.7 and 299.5 psig respectively. The temperatures of the column in the lower and upper section of the column were 158 ° C and 152 ° C at the beginning, and 172 ° C and 166 ° C at the end of the 12-hour run, respectively. The analysis of the sample taken from the heat exchanger at the end of the race indicated 0.4% ammonia, 60.8% methane, 6.7% dimetium carbonate, 27.6% methyl carbamate, 4.2% N-MMC and 0.2% unknown. The upper product contained 4.7% dimethyium carbonate and 0.1% methylamine. The result is listed in Table 2. The content of urea in the bottom of the product sample was unknown because urea could not be analyzed by means of gas chromatography due to the decomposition of urea. Examples 4A and 4B indicate the slow thermal decomposition of methyl carbamate and that the organotin compounds can be an effective catalyst for the decomposition of methyl carbamate and urea in the absence of methanoi. A too low concentration of methane in The reaction medium can promote the decomposition of the methyl carbamate or urea or both. Too high a concentration of methanoi will reduce the reaction rate w will cause the pressure in the reactor to cause the difficulty of distilling the dimethyl carbonate from the heat intercalator resulting in increased by-product formation. Therefore, it is important to maintain an optimum concentration of methanol in the reaction zone. The flow rate of the upper liquid product was increased to 2.5cc / min in Examples 5A-5B. The methyl carbamate solutions were pumped into the distiller's lower heat exchanger during the run to simulate continuous operation. When the reaction was carried out at a high fiow rate, there was little improvement compared to the lower rate of fiow (1.5 cc / m in example 3A, table 2). The higher upper rate simply diluted the dimethyl carbonate concentration from 16-18% in Example 3A to about 9%, which is undesirable for the separation of dimethylammonium from the upper liquid product. When the reaction was carried out in the absence of solvent to the triglyceride (Example 5B), the concentration of dimethyl carbonate in the top product was almost the same with a better apparent selectivity of dimethyl carbonate and the production of much less methyiamine than in Example 3B, although little change was observed in the formation of N-MMC. The concentration of dimethyl carbonate in the upper liquid product was about one-half of Example 5A, resulting in about 1/3 less removal of dimethyl carbonate from the upper liquid product compared to Example 5A as shown in FIG. Table i. Although the concentration of urea in the nc bottom products is known, the conversion of the methyl carbamate seems to be superior for example 5A than 5B due to the effective removal of the dimethylammonium carbonate and the ammonia from the reaction zone. Table 2 A Solvent in the 100 MeOH-100 200 MeOH exchanger Trigiimo int. caior Temp. ° C JOO JOO P. sup. psig mcial 39.4 207.7 final 123.9 299.5 Vei. bow. His p. cc / min 2.5 2.5 Mass balance% 96.1 98.7 Molar balance *% 88.9 87.5 Apparent MC, conv.m% 82.9 67.6 apparent seiectiviaaaes *, m% 88. / I z. z DMC 0.9 8.4 N-MMC DMC removed as 169.7 108.3 superior product, g * The content of urea in the exchanged caior was not included in the calculation. OR EXAMPLE 6A The distillation heat exchanger of the distiller was charged with 125 g of methyl carbamate, 100 g of methane, 100 g of triglyme and 24.8 g of dibuti-stannous dimethoxide. The temperature of the heat exchanger was maintained at 178-81 ° C, controlling the upper pressure during the reaction. The rate of fiow of the upper liquid product was fixed at 2.7 cc / min. An urea solution prepared by dissolving 105.6 g of urea in 2200 g of methane was pumped into it. heat exchanger to maintain a constant liquid level in the heat exchanger. The reaction was terminated after 12 hours of continuous uninterrupted operation. The result of this experiment is listed in Table 3. The change in the composition of dimethyl carbamate in the higher products during the run is illustrated in Figure 5. The pressures above the start to the end were 47.9 psig and 49 psig respectively. The temperatures of the column in the upper section of the column were 111 ° C and 104 ° C at the start and 112 ° C and 93 ° C at the end of the run of 12 hours respected. amente. While the analysis of the sample taken from the exchanger .- a 1 r > -r a l f i ri a l H o l a r v i H: a H o 1 9 h n r a c i n H i p? 1 1 S- (dimetium carbonate, 13.1% methane, 30.2% methyl carbamate, 0.8% N-MMC, 54.3% triglyceride and 0.5% unknown, the top product contained 7.3% dimetium carbonate and none of the methylamin.All the top samples taken during the 12-hour run did not contain a detectable amount of methylamine.The content of urea in the sample of background product was unknown because urea could not be analyzed by means of gases due to the urea decomposition EXAMPLE 6B The reaction was carried out using the distiller described in example 6A but without cocatalyst, the distiller's heat exchanger was charged with 125 g of methyl carbamate., 200 g of methane !, and 25.6 g of dibuti-stannous dimethoxide. The temperature of the heat exchanger was maintained at 178-180 ° C until the upper pressure was controlled during the reaction. The rate of fiow of the upper liquid product was set at 2.7 cc / min. A solution of urea prepared to dissolve 105.76g of urea in 2000s of methanol from pumping in the heat exchanger to maintain the constant liquid level in the heat exchanger. The reaction terminated after 12 hours of continuous uninterrupted operation. The result of this experiment is listed in Table 3. The change in the composition of dimethyl carbonate in the top product during the run is illustrated in Figure 5. The upper pressures at the start and end were 222 psig and 236.7 psig, respectively. The temperatures of the column in the bottom and top section of the column were 170 ° C and 166 ° C at the start and 163 ° C and 157 ° C at the end of the 12-hour run. While analysis of the sample taken from the heat exchanger at the end of the 12-hour run amounted to 8.2% of dimethylammonium carbonate, 45.3% of methanoi, 37.3% of methyl carbamate, 8.0% of N-MMC, and 0.8% unknown, the upper samples taken during the first 6 hours of run did not contain a detectable amount of methyiamine. The upper samples during the second 6 hours of running contained 0.8 to 0.1% methyiamine. The content of urea in the sample of bottom product was declined because urea could not be analyzed by means of gas chromatography due to the decomposition of urea. yu Table 3 Example 6A 6B Solvent in 100 MeOH-100 200 MeOH intercabiador Trigiimo Int. Heat Temp. ° C 355 355 P. sup. psig inciai 47.9 222 final 43.0 236.7 Vel. bow. His p. cc / min 2.7 2.7 Mass balance% 95.9 96.5 Molar balance *% 53.6 49.4 DMC 0.5 5.8 N-MMC 0 0-0. i DMC removed as 153.5 129.3 top product, g "calculated on the basis of the methyl carbamate totai and urea combined in the heat exchanger during the run. Example 6A simulates the continuous run for which a urea solution is pumped into the distiller's exchanger (reactor) to convert urea to carbonate The experiments show that urea can be converted to dimethyl carbonate at this stage, that is, it is not necessary to convert urea to methyl carbamate in one reactor and then convert methyl carbamate to dimethyium carbonate in another reactor because the extra amount of ammonia produced by reaction i can be effectively removed from the reaction zone (exchange heat) when the urea is converted to the carbamate methyl but it is possible to select the dimethylium carbonate in two stages. As shown in Table 3, when the reaction was performed according to the preferred embodiment, a superior result was obtained again; higher productivity of dimetium carbonate and lower by-product formation. When the triglyceride is not used as a cocatalyst, the solvent of the amount of N-MMC produced is 10 times greater than the reaction carried out according to the present invention. Since to convert the urea to the methyl carbamate ia urea has to react with methane, that is the methyl carbamate has to compete with the urea for the methane to produce dimetium carbonate (Reaction 2). The analysis of the bottom product taken after 12 hours of run indicates that the concentration of methane in Example 1A (with cocatalyst appears to be too low (13.1%) for reaction 1 and reaction 2 to be presented consecutively without competing for methane. The amount of triglyceride in the distiller's lower heat exchanger was too low at the start of the run indicating that When a solution of urea is pumped into the heat exchanger to produce dimethylium carbonate in a single step the ratio of triglyceride to methane used to convert the methyl carbamate to dimethyl carbonate should be readjusted, that is to say reduced. EXAMPLE 7 This example illustrates the actual production of DMC in one stage. The distillation heat exchanger was charged with 125 g of methyl carbamate, 120 g of methanoi, 80 g of triglyme and dibuti-stannous dimethoxide. The temperature of the heat exchanger was maintained at 176-18i ° C ai control the superior pressure during the uninterrupted run of 12 hours. The rate of fiow of the upper liquid product was fixed at 2 cc / min. A solution of urea prepared to dissolve 105.6 g of urea in 2200 g of methane was pumped into the heat exchanger to maintain a constant liquid level in the exchanger. The reaction was terminated after 12 hours of uninterrupted operation. The result of this experiment is listed in Table 4. The change in the DMC composition in the superior products is shown in Figure 6. The pressures above the start and end of the 12-hour run were 66 or 134.7 psig., respectively. Column temperatures in the upper bottom section of the column was 120 ° C and Ü2 ° C at the beginning and 141 ° C and 134 ° C at the end of 12 hours, respectively. While the analysis of the sample taken from the exchanger at the end of the 12-hour run indicated 3.8% carbonate of 5 dimetiol, 20.9% methane, 21.1% methyl carbamate, 1.5% N-MMC, 52.0% triglyceride , 0.2% unknown, 0.2% methylamine (or water) and 0.3% ammonia, the top product contained 9.0% dimethyl carbonate, 88.4% methane, 0.1% methylamine (or water) and 2.5% ammonia. The content of urea in the sample of the background product was unknown because urea could not be analyzed by means of gas chromatography due to the decomposition of urea. The unit is deactivated for the next year's operation. The weight to the composite top product was 5 1054 g and the weight of the urea solution pumped to the exchanger was 1252 g. The total samples taken from the unit was 210.8g. There is a lower level of liquid in the heat exchanger from 8 to 12 hours in the current. The composite overhead pipeline contained 11.5% of the gasoline, and an exhaust gas was collected for 12 hours during the reaction (very small volume of gas) and the gas outlet analysis indicated 0.05% by volume of CO. and 2.1 voi O indicating a reauciative decomposition to the methyl carbamate or urea, the continuous run the following day by pumping a Mixed solution prepared by mixing 1650 g of methane with 142.5 g of triglyceride in the exchanger. The temperature of the exchanger was maintained at 348-359 ° C when controlling the upper pressure. The rate of fiow of the upper liquid product was set at 2cc / min. The reaction was stopped after 10 hours of uninterrupted operation. The result of this experiment is listed in Table 4. The upper pressure at the start or end of the uninterrupted run for 10 hours was 232.1 and 201.7 psig, respectively. Column temperatures in the lower and upper section of the column were 120 ° C and Ü2 ° C at the start and 161 ° C and 156 ° C at the end of the 10-hour run, respectively. While the analysis of the sample taken from the exchanger at the end of the 10-hour run (total of 22 hours from the start) indicated 1.7% of dimethyl carbonate, 22.2% of methane, and 1.5% of methyl carbamate, .3% of N-MMC, 71.9% of triglyceride, 1.3% unknown and 0.1% of air, the superior product contained 3.8% dimetium carbonate, 94.94% methane and 1.2% ammonia. The content of urea in the background product was unknown, because urea could not be analyzed by means of gas chromatography due to the decomposition of urea. The weight of the composite top product was 956 g and the weight of the mixed solution was 956 g and the weight of the mixed solution pumped into the exchanger was 1088. The total weight of the samples taken from the unit was 197.2 g. The total weight of inventory material collected from the column and the exchanger was 249. The output gas was collected during the run (very small volume of gas) and contained 10.0% in volume of CO and 0.7 voi of =. The change of the DMC composition in the upper product for the second portion of the run is included in Figure 6. The concentration of DMC in the upper product is very desirable because the DMC separation is an expensive process due to the formation of binary azotropes with methanol. As shown in Table 4 the selectiviaad DMC is excellent. (98.2%). When the urea solution is pumped directly into the heat exchanger in the one stage synthesis process, a very small methyl carbamate decomposition results with the best selectivity hitherto.

Taoia Solvent 120 MeOH / 80 TG Pumped solution Urea in MeOH MeOH / TG (10 (12 h) h) Interchange. Temp. ° C 349-357 358-359 P. sup. psig inciai 66 232.1 final 134.7 201.7 Vel. prod. His p. cc / min Mass balance% 100.1 Molar balance *% yy.b Conversion ap.?r,% 98.3 Selectivity ',% DMC 98.2 N-MMC 1.6 DMC removed as 141.3 209.1 superior product, s ap; Apparent * Calculated on the basis of the methyl acetate and the urea consumed during the reaction, assuming that no urea was left undisturbed in the reactor at the end of the run. for the run of the first 12 oras. for the run of the total 22 hours.

Claims (10)

1. CLAIMS I. - A process for the production of diacyl carbonates consisting of the steps of: (a) feeding urea and a primary alcohol to a reaction zone; (b) feeding an organotin compound and a solvent containing an electron donor atom, with a high boiling point to the reaction zone and (c) concurrently in that reaction zone (i) reacting a portion of the primary alcohol and urea in the presence of the organotin compound and the solvent containing an electron donor atom, with a high boiling point to produce diakaryium carbonate; and (ii) removing the diaryl carbonate and ammonia from the reaction zone in the form of vapor.
2. 2. The process according to claim 1 wherein the ammonia and a portion of the alcohol are removed from the reaction zone. vapor form and is extracted together with the diachiium carbonate as superior products.
3. 3. The process according to claim 2, wherein the upper products are partially condensed to separate the ammonia in the form of vapor from the diacyl carbonate and the alcohol in liquid form.
4. 4.- Proceed according to claim I in where the organotin catalyst is dibonthyl dimethoxide "-year.
5. 5. The process according to claim 1 wherein the solvent containing an electron donor atom, with a high boiling point, is polysiolic ether.
6. 6. The process according to claim 1 wherein the solvent containing an electron donor atom with a high boiling point consists of bidentate binders that form 1: 1 bidentate adducts and / or monodentates 1: 2 with R ' SnX (X = Ci, R'O, R'COO or R'COS), R 'SnX, R' SnO, Ph .. R'SnX or Ph ... SnX, (where R '= CH .. n = 0, io 2 and q = 12) and mixtures thereof.
7. 7. The process according to claim 6 wherein the solvent containing an electron donor atom, with a high boiling point, consists of triethylene glycol ether dimethyium.
8. 8. The process according to claim 1 wherein the solvent containing an electron donor atom with a high boiling point consists of materials having the general formula ROCH (CH) CH 01 R, wherein R is selected independently of the alkyl, aikaryl or arachidium portions with 1 to 12 carbon atoms, k = 0,1,2 or 3 and m = 1, 2,3,4 or 5 and their mixtures.
9. 9. - The process according to claim 1 wherein the primary alcohol is methanol and the dialkyl carbonate is dimethyl carbonate.
10. 10. A process for the production of dimethyl carbonate consisting of the steps of: (a) feeding urea and methane to the exchanger of a distiller; (b) feeding an organotin compound and solvent / cocatalyst of triethylene glycol dimethyl ether to the heat exchanger; (c) concurrently in that heat exchanger (i) reacting a portion of the methanol and urea in the presence of the organotin compound and the triethylene glycol dimethyl ether cocataizator to finally yield dimethyium carbonate; and (ii) removing the dimethylium carbonate and the ammonia from the heat exchanger in vapor form. The process according to claim 10, wherein a portion of the methane is removed from the exchanger in the form of steam and extracted from the distillation column together with the dimethylium carbonate as the top product. 12. The process according to claim 11 characterized in that the superior products are They partially condensed to separate the dimethyl carbonate and the methanoi in liquid form. 13. A homogeneous catalyst useful for reacting urea and primary alcohols to produce diacylium carbonates consisting of a compound of an organotin compound with a bidentate binder that forms bidentate adducts 1: 1 and / or monodentates 1: 2 with R ' _, SnX_ (X = C1, R'O, R'COO or R'COS), R ':, SnX, R' SnO, Ph; .. "R'SnX or Ph ..SnX. (where Rl = CpH_ ".: n = 0, l or 2 and q = l to 12) and mixtures of them. 14. The catalyst according to claim 13, characterized in that the organotin compound consists of dibuti-stannous dimethoxide. 15. The catalyst according to claim 13, characterized in that the electron-boiling, high boiling point compound consists of triethylene glycol dimetiium ether. 16. The catalyst according to claim 13, characterized in that the organotin compound consists of dibutyltin dimethoxide and the compound with high boiling point electron atom consists of triethylene glycol dimethyl ether. 17. A homogeneous catalyst according to claim 13 comprising a composite of an organotin compound with materials having the formula general RO [CH (CH), CH0] ", R, wherein R is independently selected from the alkyl, aikaryl or arachidium portions with 1 to 12 carbon atoms, k = 0,1,2 or 3 and m = i , 2,3,4 or 5 and their mixtures. 18. The homogeneous catalyst according to claim 6, wherein the organotin compound consists of R'2SnX2 R'2SnX, R 'SnO, Ph: .. rR'SnX, or Ph ..SnX or mixtures thereof.