NO166035B - PROCEDURE FOR THE PREPARATION OF ORGANIC CARBONATES BY TRANSFERING A CARBON ACID DIETER. - Google Patents

Abstract

1. Process for the preparation of organic carbonates by transesterification of a diester of carbonic acid and of at least one alcohol heavier than that or those formed by transesterification, in the presence of a transesterification catalyst based on a basic ionic salt, characterized in that the said transesterification operation is additionally carried out in the presence of a complexing compound capable of at least partially solubilizing the said salt in the reaction mixture by complexing its cation and at least partially dissociating the said salt.

Description

The present invention relates to a method for producing organic carbonates by transesterification of a carbonic acid diester with an alcohol.

These and further features of the invention appear in the patent claims.

From US-PS No. 3,642,858 and DE-PS No. 2,749,754 it is known to prepare dialkyl carbonates by transesterification of an alkylene carbonate or a dimethyl carbonate with an alcohol in the presence of an alkali metal salt as catalyst.

A method has now been found which allows the amount of basic catalyst used to be reduced and/or the reaction time to be shortened.

The present invention thus relates to a method for the production of organic carbonates by transesterification of a carbonic acid diester with at least one alcohol that is heavier than the alcohol or alcohols formed by the above-mentioned transesterification, in the presence of a transesterification catalyst based on a basic ion salt, and the distinctive in the method according to the invention, said transesterification is also carried out in the presence of a complex-forming compound which is capable of dissolving, at least partially, the above-mentioned salt in the reaction mixture by complexing its cation and dissociating, at least partially, the above-mentioned salt.

The carbonic acid diester used has the general formula:

wherein R and R' are the same or different and represent straight-chain or branched C1-C1Q alkyl radicals, preferably C1-C3 alkyl radicals, or straight-chain or branched C3-C1Q alkenyl, preferably C3-C4<a>lkenyl.

Examples of the carboxylic acid diester include dimethylcarbonate, diethylcarbonate, dipropylcarbonate, methylethylcarbonate, diallylcarbonate, methylallylcarbonate, propylallylcarbonate and dimethylallylcarbonate.

The alcohol(s) used are the monoalcohols or polyols whose only property is that they are heavier than the alcohol(s) formed during transesterification.

Thus, the above-mentioned alcohol(s) can be a saturated or unsaturated, straight-chain or branched aliphatic monoalcohol with 2 to 22 carbon atoms, preferably 8 to 18 carbon atoms, a cycloaliphatic monoalcohol with 6 carbon atoms, a saturated or unsaturated, straight-chain or branched aliphatic polyol with 2 to 10 carbon atoms, preferably 2 to 6 carbon atoms, containing from two to four alcohol functions, a monoalkyl ether with 1 to 3 carbon atoms, preferably 1 to 2 carbon atoms, of a saturated or unsaturated, straight-chain or branched aliphatic diol with 2 to 10 carbon atoms, preferably 2 to 6 carbon atoms, a polyoxyalkylene glycol or a polyoxyalkylene glycol monoether, with the formula HO—£—r—o—J—nZ in which Z is hydrogen or an alkyl radical with 1 to 3 carbon atoms, preferably 1 to 2 carbon atoms, r is a straight-chain or branched alkylene radical with 2 to 3 carbon atoms and n ranges from 2 to 4, preferably from 2 to 3, benzyl alcohol, phenol, 4,4'-biphenyldiol and/or bis(hydroxyphen yl)alkanes with an aliphatic chain of 1 to 3 carbon atoms.

Examples of alcohols include ethanol, propanol, isopropanol, butanols, 2-ethylhexanol, lauryl alcohol, cetyl alcohol, cyclohexanol, allyl alcohol, methallyl alcohol, butanediols, hexanediols, glycerol, pentaerytriol, mono-, di-, tri- and the tetraethylene glycols, the mono-, di-, tri- and tetrapropylene glycols and likewise their methyl or ethyl monoether or 2,2-bis(4-hydroxyphenyl)-propane.

The catalysts used are commonly used catalysts for transesterification selected from among the basic ion salts of the type hydrides, hydroxides, alcoholates, acetates, carbonates,

bicarbonates or acetylacetonates of alkali metals.

Particular mention should be made of sodium hydroxide, potassium hydroxide, lithium hydroxide, sodium or potassium carbonate.

The complexing compound capable of dissolving and dissociating, at least partially, the transesterification catalyst is selected from: a sequestering agent as disclosed in FR-PS No. 2,450,120

with formula:

N(CHR1-CHR2-0-(CHR3-CHR4-o)n-R5)3 (I)

where n is an integer greater than or equal to 0 and less

or equal to 10 (O^n^lO), R^, R2, R3 and R4 are the same or different and represent a hydrogen atom or an alkyl radical of 1 to 4 carbon atoms and R5 represents an alkyl radical or cycloalkyl of 1 to 12 carbon atoms, a phenyl radical or a radical -Cm H2m - 0 or <cmH>2m+l-0-' in which m is a number1 between 1 and 12 (lsm£l2),

a macrocyclic polyether called "crown ethers" specified in FR-PS

No. 2,026,481, i.e., a macrocyclic polyether having 12 to 40 ring atoms and consisting of 4 to 10 -O-X- units wherein X is either -CHR6-CHR7- or -CHR5-CHR8CR9R7-, wherein Rg, R7, Rq and R9 are the same or different and are a hydrogen atom or an alkyl radical of 1 to 4 carbon atoms and one of the X's can be -CHR6-CHR3-CR9R7 when the -O-X units comprise the group -O-CHR6-CHR7-, or

a macrocyclic or bicyclic compound called "cryptate", as stated in FR-PS No. 2,052,947 and with general formula Ila and Ilb:

in which:

Y represents N,

A represents an alkylene group with 1 to 3 carbon atoms, D represents 0 or N-R^ in which R^ represents a

alkyl radical with 1 to 6 carbon atoms,

R^ represents an alkyl radical of 1 to 6 carbon atoms and p, q and r which are the same or different are whole numbers between 1 and 5.

When the complex-forming compound is a sequestering agent of formula (I), R 1 , R 2 , R 3 and R 4 are preferably a hydrogen atom or a methyl radical and R 5 and n have the above meaning.

Among the latter, the agents in which n is greater than or equal to 0 and less than or equal to 6 and in which R 5 represents an alkyl radical with 1 to 4 carbon atoms are particularly preferably used.

Examples of sequestering agents include: tris-(3-oxabutyl)amine with formula:

N-(CH2-CH2-0-CH3)3,

tris-(3,6-dioxaheptyl)amine with formula:

N-(CH2-CH2-0-CH2-CH2-0-CH3)3,

tris-(3,6,9-trioxadecyl)amine with formula:

N-(CH2-CH2-0-CH2-CH2-0-CH2-CH2-0-CH3)3, tris-(3,6-dioxaoctyl)amine with formula: N-(CH2-CH2-0-CH2-CH2-0-C2H5)3, tris-(3,6,9-trioxaundecyl)amine with formula: N-(CH2-CH2-0-CH2-CH2-0-CH2-CH2-0-C2<H>5)3,

tris-(3,6-dioxanonyl)amine with formula: N-(CH2-CH2-0-CH2-CH2-0-C3H7)3, tris-(3,6,9-trioxadodecyl)amine with formula: N-(CH2-CH2-0-CH2-CH2-0-CH2-CH2-0-C3H7)3, tris-(3,6-dioxadecyl)amine with formula: N-(CH2-CH2-0-CH2-CH2-0-C4H9)3, tris-(3,6,9-trioxatridecyl)amine of formula: N-(CH2-CH2-0-CH2-CH2-0-CH2-CH2-0-C4<H>9)3, tris-(3,6 ,9,12-tetraoxatridecyl)amine with formula: N-(CH2-CH2-0-(CH2-CH2-0)3-CH3)3,

tris-(3,6,9,12,15,18-hexaoxanonedecyl)amine with formula:

N-(CH2-CH2-0-(CH2-CH2-0)5-CH3)3,

- tris-(3,6-dioxa-4-methylheptyl)amine with formula: N-(CH2-CH2-OCH-(CH3)-CH2-0-CH3)3,

tris-(3,6-dioxa-2,4-dimethylheptyl)amine with formula:

N-(CH2CH-(CH3)-OCH(CH3)-CH2-0-CH3)3,

As examples of crown ethers that can be used according to the present invention, the following can be mentioned:

Examples of macrocyclic or bicyclic "cryptate" compounds can be mentioned:

In accordance with the method according to the present invention, the transesterification is carried out with respectively the following ratio between the various reaction components: the ratio between the number of alcohol functions/number of moles carboxylic acid diester depends on the number of ester functions (one or two) to be converted, as transesterification of two ester functions is preferably carried out in the presence of an excess of alcohol in relation to the relevant stoichiometry and transesterification of an ester function is preferably carried out in the presence of an excess of a carboxylic acid diester in ratio to the relevant stoichiometry, the above ratio being in the order of magnitude from 1/20 to 20/1, preferred in

order of magnitude from 0.2 to 2.5,

the molar ratio catalyst/reaction component (i.e. mol catalyst/mol carboxylic acid diester in the case of transesterification of two ester functions or mol catalyst/- alcohol function in the case of transesterification of a single -4 -3 ester function) is in the order of magnitude from 10 to 5 x 10 -4 - 3 preferably in the order of magnitude from 2 x 10 to 2 x 10 the molar ratio of complexing compound/catalyst is in the order of magnitude from 0.001 to 0.1, preferably in the order of magnitude from 0.003 to 0.1, and especially in the order of magnitude from 0.004 to 0.03, since this ratio can thus vary within a large range, but preferably an excessively large amount of basic catalyst is not used, especially when the diester and/or alcohol used are unsaturated (unsaturated) to avoid discoloration of the final product.

The process according to the present invention can be carried out in the presence of an "azeotrope-forming" compound capable of forming azeotropes with the alcohol or alcohols formed by the transesterification in order to facilitate the elimination of this or these alcohols, the nature of the above-mentioned "azeotrope-forming " compound, of course, is a function of the nature of the alcohol(s) to be removed. A person skilled in the art will find the "azeotrope-forming" compound that is most suitable without difficulty, but it can e.g. mention is made of hexane, heptane, cyclohexane, cyclopentane, toluene, xylene, etc.

The method according to the present invention is carried out at a pressure close to atmospheric pressure. To avoid discoloration and oxidation, it is generally carried out under an inert atmosphere, particularly when the carbonate to be produced has one or more allyl groups (to avoid polymerization reactions).

The minimum temperature in the reaction mixture is of course a function of the reaction kinetics in that it must be high enough to initiate the transesterification reaction and allow the elimination of the alcohol(s) formed or their azeotropes by distillation. This temperature is generally at least 40°C.

The maximum temperature in the reaction mixture, i.e. at the end of the reaction, is not critical when the alcohol(s) and carbonic acid diester used are saturated. When the alcohol(s) and/or the diester, on the other hand, are unsaturated (unsaturated), this temperature must be lower than the temperature that leads to the formation of by-products that cause discolouration. This maximum temperature is generally less than 120°C.

The temperature of the vapors is close to the boiling point temperature of the alcohol(s) formed or their azeotropes to allow reflux of the alcohol(s) formed or their azeotropes.

At the end of the reaction, the excess of formed reaction components can e.g. removed by distillation under reduced pressure. The method according to the present invention is particularly adapted to the production of diallyl carbonate and diethylene glycol bis(allyl carbonate).

In the method of the present invention, diallyl carbonate is obtained by transesterification of allyl alcohol and a dialkyl carbonate with straight or branched C3~alkyl radicals in the presence of the above-mentioned transesterification catalyst and complexing compound.

The transesterification reaction is carried out under an inert atmosphere and preferably in the presence of an azeotrope-forming compound such as hexane, at a temperature such that the temperature of the reaction mixture at the end of the reaction does not exceed 120°C and the temperature of the vapors is close to the boiling point temperature of the alcohol or azeotrope formed to allow reflux of this alcohol or its azeotrope.

The amount of reaction components used corresponds to the following molar ratio: allyl alcohol/diester from 2/1 to 20/1, preferably from 2.2

to 2.5,

-4 -3 catalyst/diester from 10 to 5 x 10 , preferably from

2 x 10~<4> to 2 x IO"<3>,

complexing compound/catalyst from 0.001 to 0.1, preferably from 0.003 to 0.1 and particularly preferred from 0.004 to 0.03.

According to the method of the present invention, diethylene glycol bis(allyl carbonate) is obtained by transesterification of diallyl carbonate with diethylene glycol in the presence of the above-mentioned transesterification catalyst and the above-mentioned complex-forming compound.

The reaction is carried out under an inert atmosphere, possibly in the presence of an azeotrope-forming compound such as toluene or xylene, at a temperature such that the temperature of the reaction mixture at the end of the reaction does not exceed 120°C and the temperature of the vapors is close to the boiling point temperature of the allyl alcohol or, possibly, the formed azeotrope to allow reflux of the formed alcohol or its azeotrope.

The amount of reaction components preferably used corresponds to the following molar ratio: diethylene glycol/diallyl carbonate from 1/40 to 1/2, preferred ket from 1/10 to 1/4 (or number of alcohol functions/mol of diallyl carbonate from 1/20 to 1, preferably from 0.2 to 0.5),

-4 -2 catalyst/diethylene glycol from 2 x 10 to 10' preferably from 4 x 10 to 4 x 10 (or mol catalyst/--4 -2

number of alcohol functions from 10 to 0.5 x 10 , preferably from 2 x 10~<4> to 2 x IO<-3>),

complexing compound/catalyst in the order of magnitude from 0.001 to 0.1, preferably from 0.003 to 0.1 and particularly preferred from 0.004 to 0.03.

The inorganic carbonates produced according to the method of the present invention can be used as such and are particularly known as solvents for cellulose compounds, as plasticizers, etc., the unsaturated carbonates can be used as monomers for the production of polymers with optical properties.

The following examples illustrate the present invention:

Example 1

In an inert reactor of 300 liters at atmospheric pressure and which is equipped with a distillation column, condenser and an azeotropic decanter, introduce under ONE nitrogen atmosphere:

68 kg (755 mol) dimethyl carbonate (DMC),

103.5 kg (1783 mol) allyl alcohol, which corresponds to et

ratio of alcohol function/mol DMC of 2.36,

30 kg technical hexane,

21.2 g (0.53 mol) NaOH, which corresponds to a molar ratio NaOH/DMC of 0.07 x 10~<2>,

_3 1 g (4.55 x 10 mol 1, 4, 7, 10, 13-pentaoxacyclopene-tadecane (15 - crown - 5 ether), which corresponds to a molar ratio complexing compound/catalyst of 8.6 x IO<-3>.

The reaction mixture is stirred, after which it is brought to a temperature which allows reflux of the heteroazeotrope hexane-methanol at atmospheric pressure.

After equilibration of the column, the methanol formed is extracted, the temperature not exceeding 50°C. This extraction is carried out until the reaction mixture from the reactor, followed by gas phase chromatography, is as follows: methanol: trace

DMC : tracks

molar weight ratio of diallyl carbonate/methylallyl carbonate greater than or equal to 15.5.

The extraction of methanol lasts for nine hours.

The products from the reaction mixture contained in the reactor are then separated by fractional distillation, first at atmospheric pressure and then at reduced pressure. The molar yield of diallyl carbonate based on DMC is at least 95% and this can be further improved by recycling the methylallyl carbonate.

Example 2

The transesterification reaction described in ex. 1 is carried out in the absence of the complexing compound and with an increased amount of NaOH. It is established that 0.250 kg of NaOH (6.25 mol) is needed, i.e. 11.8 times more than in ex. 1, to likewise obtain, after nine hours, a similar reaction mixture towards the end of the methanol extraction.

Example 3

The rearrangement described in ex. 1 is carried out by

application of:

as catalyst: 63.5 g (0.96 mol) KoH, which corresponds to et molar ratio KoH/DMC of 0.13 x 10~<2>,

_3

as complexing compound: 7.6 g (28.7 x 10 mol)

1, 4, 7, 10, 13, 16-hexaoxacyclooctadecane (18 - crown - 6 ether), which corresponds to a complexing compound/catalyst molar ratio of 0.03.

Methanol extraction for nine hours is required to obtain a similar reaction mixture as that in ex. 1.

Example 4

The changeover is carried out as indicated in ex. 3 in the absence of complexing compound and using 350 g (5.3 mol) of CoH (corresponding to a catalyst/DMC molar ratio of 0.7 x 10~<2>) instead of 63.5 g of CoH.

A reaction mixture similar to that in ex. 1 after twelve hours of methanol extraction.

It is found that compared to e.g. 3, the presence of a complexing compound reduces the amount of catalyst used by 5.5 times and the reaction time is reduced by 25%.

Example 5

Into an inert reactor of 2 liters which is equipped with a distillation column and under a nitrogen atmosphere is introduced: 1421.5 g (10 mol) diallyl carbonate,

106.1 g (1 mol or 2 OH functions) diethylene glycol (DEG) corresponding to a ratio alcohol function/mol diallyl carbonate of 0.2,

_3

0.138 g (10 mol) of potassium carbonate corresponding to a catalyst/DEG molar ratio of 10<-3> or a molar ratio of -_3

keep catalyst/OH function at 0.5 x 10 ,

-3 -5

2.64 x 10 g (10 mol) 18 - crown - 6 ether, which corresponds to a complexing compound/catalyst molar ratio of 0.01.

The reaction mixture is placed under reduced pressure (between 13332 Pa and 26664 Pa) and brought to a temperature in the order of 100 to 120°C to allow distillation of the allyl alcohol formed.

The reaction is interrupted three hours after starting allyl alcohol distillation.

The potassium carbonate is neutralized, after which excess diallyl carbonate is eliminated by distillation (final pressure less than 1333 Pa and maximum temperature 150°C).

260 g of the final product is recovered (corresponding to a weight yield of 94.5% in relation to the stoichiometry of the reaction for the formation of pure monomer) whose color is set to between 5 and 10 HAZEN (Norm AFNOR NF-T-20-605)

The composition of said product determined by gel permeation chromatography is as follows:

monomer : 84.5%

dimer : 14.0%

trimer : 1.5%

The viscosity is 13.8 x IO<-6> m<2>/s at 25°C.

Example 6

The procedure described in ex. 5 is repeated using the following catalyst/complexing compound: _3

as catalyst: 10 mol lithium hydroxide instead of 10~<3> mol potassium carbonate,

_5

as a complexing compound: 10 mol 12 - crown - 4

ether.

After three hours of reaction, the experimental product yield is, as before, 94%.

The color of the final product is between 5 and 10 HAZEN.

The product has the following composition:

monomer : 82.7%

dimer : 15.4%

trimer : 1.3%

The viscosity is 14 x IO<-6> m<2>/s at 25°C.

Example 7

The procedure described in ex. 5 is repeated, using the following as catalyst/complex-forming compound: as catalyst: 10 <3> mol potassium carbonate,

_5

as complexing compound: 10 mol tris(3,6-dioxaheptyl)amine instead of 10<-5> mol 18 - crown - 6 ether.

After three hours of reaction, the experimental product yield is, as before, 94%.

The product has the following composition:

monomer : 83.8%

dimer : 14.5%

trimer : 1.7%

The viscosity is 13.9 x 10~<6> m<2>/s at 25°C.

Example 8

The procedure according to e.g. 5 was repeated using the following catalyst/complexing compound: _3

as catalyst: 10 mol potassium carbonate,

_5

as complexing compound: 10 mol hexaoxa-4,7,13,16,21,24 diaza-1,10 bicyclo-8,8,8-hexacosane-

_5

(cryptate-2,2,2) instead of 10 mol 18 - crown - 6 ether.

After three hours of reaction, the product yield is, as before, 94.5%.

The product has the following composition:

monomer : 84.7%

dimer : 14%

trimer : 1.3%

The viscosity is 13.7 x 10 <6> m<a>/s at 25°C.

Example 9

The procedure described in ex. 5 was repeated using the following catalyst/complexing compound: -3 -3

as catalyst: 2.3 x 10 mol KoH (instead of 10 mol potassium carbonate), which represents a molar ratio of catalyst/DEG of 2.3 x 10 or a molar ratio of

catalyst/OH function of 1.15 x 10 _3,

as a complexing compound: 11.4 x 10<->^ mol (instead

-5

for 10 mol) 18 - crown - 6 ether, which corresponds to a molar ratio of complexing compound/catalyst close to 5 x IO<-3>.

After three hours of reaction, the product yield obtained is, as before, 94.5%.

The product has the following composition:

monomer : 84.2%

dimer : 14.2%

trimer : 1.4%

The viscosity is 13.8 x 10~<6> m<2>/s at 25°C.

Example 10-21

The procedure described in ex. 5 was repeated, varying the amounts of potassium carbonate and 18-crown-6 ether.

The results obtained are shown in Table I.

Example 22

The procedure described in ex. 5 was repeated using the following reaction components:

12 mol diallyl carbonate,

1 mol DEG, which corresponds to a ratio alcohol function/mol diallyl carbonate of 0.17,

_3

1.1 x 10 mol of potassium carbonate, which corresponds to a molar ratio

catalyst/OH function of 0.55 x IO<-3>,

30 x IO-3 mol 18 - crown - 6 ether, which corresponds to a complexing compound/catalyst molar ratio of 0.027.

After three hours of reaction, a product with the following composition was obtained:

. monomer: 87.0%

. dimer : 12.0%

. trimer : 1.0%

Example 23 - Preparation of dicyclohexylcarbonate.

In a 1 liter reactor, introduce under a nitrogen atmosphere:

- 1 mol allyl carbonate,

- 10"<3> mol KOH,

_5

- 10 mol 18 - crown - 6 ether.

At 110°C, 2 mol of cyclohexanol are introduced using a feed funnel over the course of two hours. At the end of the addition of this alcohol, the reaction mixture is kept at 140°C and the reaction is allowed to continue for four hours and 30 minutes. During this time, the allyl alcohol formed is removed by distillation. After neutralization by KOH, the residue is filtered.

In gas phase chromatography, one finds:

allyl cyclohexyl carbonate: 0.03 mol

dicyclohexyl carbonate: 0.725 mol

The total yield in relation to the starting material which has reacted effectively is close to 95%.

Example 24 - Preparation of dipropvlenalvcolbisalvl carbonates

The procedure described in ex. 5 was repeated as DEG

(1 mol) was replaced with dipropylene glycol (1 mol).

The composition of the obtained product determined by gel chromatography is as follows:

CH2 = CH -CH2 C03 C3H6 0 C^ CC>3 CH^CH = CH2 86.3%

CH2 = CH -CH2( C03 C3H6 O C^) 2 C03 CH^CH = CH2 12.5%

CH2 = CH -CH2( C03 C3H6 O C^ C03 CH^CH = CH2 1.2%

The yield calculated according to dipropylene glycol is 100%.

Example 25 - Preparation<g> of tetraethylenal carbon bismetyl carbonates

In a reactor of 1 liter, introduce under a nitrogen atom sphere: dimethyl carbonate: 10 mol

- KOH : 10~<2> mol

18 - crown - 6 ether: 1.1 x 10 mol

The mixture is then heated to approximately 80°C. Using a feed funnel, 1 mol of tetraethylene glycol is added over the course of 40 minutes. The temperature in the reaction mixture is then gradually increased to 98°C, the temperature at the top of the column not exceeding 60°C (boiling of the azeotrope methanol-methylcarbonate). After three hours, the distillation is stopped. KOH is neutralized and excess dimethyl carbonate is distilled. The reaction residue is filtered at room temperature. The composition determined by gel chromatography is as follows:

- CH3 C03 (CH2)2 0 (CH2)2 O (CH2)2 O (CH^ <C>03 CH3 = 74%

- CH3 [C03 (CH2)2 O (CH2)2 O (CH2)2 0 (CH,,)^ C03 CH3 = 22%

- CH3 [C03 (CH2)2 0 (CH2)2 0 (CH2)2 O (CH,,)^ C03 CH3 = 4%

The yield calculated according to tetraethylene glycol is 100%.

Example 26 - Preparation of diethylene glycol monoether carbonates. -

In a 1 liter reactor, introduce under a nitrogen atmosphere: diethylene glycol monoethyl ether: 2 mol

- K2C03 : 2.9 x 10-3 mol

_5

18 - crown - 6 ether : 1.3 x 10 mol dimethyl carbonate : 1.33 mol - hexane : 5.25 mol (1/3 is placed in a feed funnel to compensate for that which is distilled together with formed methanol).

The reaction mixture is kept at 60°C and must not exceed 80°C.

The distillate is only extracted when the temperature at the top of the column is less than or equal to 47°C (the temperature for boiling the heteroazeotrope hexane-methanol). When the distillate only gives one phase, the reaction is stopped. Potassium carbonate is neutralized and excess carbonyl carbonate is removed by distillation.

The end product is filtered and analyzed by gas phase chromatography.

The area percentages give:

diethylene glycol monoethyl ether: 0.28 mol

" C2H5 ° C2H4 ° C2H4 C°3 °H3' °'31 "^

" C2H5 ° C2H4 ° C2H4 C°3 C2H4 ° C2H4 ° C2H5 : °'7° mCl

Total yield calculated according to diethylene glycol monoethyl ether is 99%.

Example 27 - Preparation of 2-ethyl-1-hexanol carbonates.

Into a 1 liter reactor under a nitrogen atmosphere: 2-ethyl-1-hexanol : 2 mol

- KOH : 3 x 10~<3> mol

-5

18 - crown - 6 ether : 7.5 x 10 mol

- dimethyl carbonate: 1.33 mol

- hexane: 3.9 mol (1/3 is placed in a feed funnel).

The experiment is carried out as in ex. 26.

Gas phase chromatography gives:

2-ethylhexanol: 0.31 mol

CH -CH.-CH -CH0 - CH-CH -CO CH : 0.43 mol

3 2 2 2* j *j ^

<C>2<H>5

CH_-CH -CH-CH- - CH-CHo-C0_ CH CH - CH-CH -CH-CH : 0.63 mol 3222 K| \C] 2H5

The experimental yield according to 2-ethyl-1-hexanol which has reacted is 99%.

Example 28 - Production of cyclic 1. 2-butanediol carbonate. In a 1-liter reactor, introduce under a nitrogen atmosphere: 1,2-butanediol: 1 mol

dimethyl carbonate : 2 mol

K2C03 : 3.6 x 10~3 mol

_5

18 - crown - 6 ether : 1.3 x 10 mol

hexane : 3.84 mol (1/3 in a feed funnel). The procedure is the same as in ex. 26. It is achieved

0.95 mol 1,3-dioxolan-2-one-4-ethyl:

i.e. a yield of 95% according to the diol used.

Claims (11)

1. Procedure for the production of organic carbonates by transesterification of a carbonic acid diester with general formula: in which R and R' are the same or different and are straight-chain or branched alkyl radicals of 1 to 10 carbon atoms, or straight-chain or branched alkenyl of 3 to 10 carbon atoms, with at least one alcohol heavier than the one or more formed by the above transesterification, in presence of a transesterification catalyst selected from a hydride, hydroxide, alcoholate, acetate, carbonate and bicarbonate or acetylacetonate of alkali metals on the basis of a basic ion salt, characterized in that the above-mentioned transesterification is also carried out in the presence of a complexing compound selected from a sequestering agent of general formula N-(CHR2-CHR2-0-(CHR3-CHR4-O)n-R5)3 (I) wherein n is an integer greater than or equal to 0 and less than or equal to 10 (O^n^lO) , Rj_ , R2( R3 and R4 are the same or different and are a hydrogen atom or an alkyl radical of 1 to 4 carbon atoms and R5 is an alkyl radical or cycloalkyl of 1 to 12 carbon atoms, a phenyl radical or a radical-<CmH>2m-0 or cmH2ni+ i_0_' nvori m is a number between 1 and 12 (l£m^l2), or a macrocyclic polyether, "crown ether", having 12 to 40 atoms in the ring and consisting of 4 to 10 -O-X- units where X is either - CHR5-CHR7- or -CHR5-CHR8-CR9R7-, wherein R6, R7, Rq and Rg are the same or different and are a hydrogen atom or an alkyl radical with 1 to 4 carbon atoms and one of the X's can be -CHR5-CHR8- CR9R7- when the -O-X- units comprise the group -O-CHR6-CHR7-, or a macrocyclic or bicyclic "cryptate" compound of formula IIa and IIb in which: - Y is N, - A is an alkylene group with 1 to 3 carbon atoms, D is 0 or N-R^ wherein R^ is an alkyl radical of 1 to 6 carbon atoms, R^q is an alkyl radical of 1 to 6 carbon atoms, and p, q and r which are the same or different are integers between 1 and 5, which is able to dissolve at least partially the above-mentioned salt in the reaction mixture by complexing its cation, and dissociate, at least partially, the above-mentioned salt, the above-mentioned transesterification being carried out in accordance with the following ratio between the various reaction components: number of alcohol functions/number of moles of carboxylic acid diesters in the order of magnitude from 1/20 to 20/1, molar ratio catalyst/reaction component in the order of magnitude from 10~4 to 5 x 10~<3>, - molar ratio complexing compound/catalyst in the order of magnitude from 0.001 to 0.1. 2. Process as stated in claim 1, characterized in that the same or different straight-chain or branched alkyl radicals with 1 to 3 carbon atoms or straight-chain or branched alkenyl with 3 to 4 carbon atoms are used as R and R'. 3. Process as stated in claims 1 and 2, characterized in that the above-mentioned alcohol is used as a saturated or unsaturated, straight-chain or branched aliphatic monoalcohol with 2 to 22 carbon atoms, a cycloaliphatic monoalcohol with 6 carbon atoms, a saturated or unsaturated, straight-chain or branched aliphatic polyol of 2 to 10 carbon atoms containing from 2 to 4 alcohol functions, a monoalkyl ether of 1 to 3 carbon atoms of a saturated or unsaturated, straight-chain or branched aliphatic diol of 2 to 10 carbon atoms; a polyoxyalkylene glycol or a polyoxyalkylene glycol monoether of the formula HO -{— r-0 —3—nZ in which Z is hydrogen or an alkyl radical with 1 to 3 carbon atoms, r is a straight-chain or branched alkylene radical with 2 to 3 carbon atoms and n is from 2 to 4 ; benzyl alcohol, phenol, 4,4'-biphenyldiol and/or bis(hydroxyphenyl)alkanes with an aliphatic chain of 1 to 3 carbon atoms. 4. Method as stated in claims 1 - 3, characterized in that sodium hydroxide, potassium hydroxide, lithium hydroxide, sodium carbonate or potassium carbonate is used as catalyst. 5. Method as stated in claims 1 - 4, characterized by the ratios used between the various reaction components are as follows: number of alcohol functions/number of moles of carbonic acid diesters in the order of magnitude from 0.2 to 2.5, mole ratio of catalyst/reaction component in the order of magnitude from 2 x 10"<4> to 2 x 10<-3>' - molar ratio complexing compound/catalyst in the order of 0.004 to 0.03. 6. Method as stated in claims 1 - 5, characterized in that the above-mentioned transesterification is carried out in the presence of a compound which forms azeotropes with the alcohol(s) formed. 7. Method as stated in claims 1 - 6, characterized by the temperature used in the reaction mixture being at least 40°C and less than 120°C. 8. Process as stated in claims 1 - 7, characterized in that a dialkyl carbonate with straight-chain or branched alkyl radicals with 1 to 3 carbon atoms is transesterified under an inert atmosphere to diallyl carbonate with the aid of allyl alcohol, the amount of reaction components used having the following molar ratio: - allyl alcohol /dialkylcarbonate from 2/1 to 20/1, -4 -3 - catalyst/dialkylcarbonate from 10 to 5 x 10 complexing compound/catalyst from 0.001 to 0.1. 9. Method as stated in claim 8, characterized in that the amount of reaction components used has the following molar ratio: - allyl alcohol/dialkyl carbonate from 2.2 to 2.5, -4 -3 - catalyst/dialkyl carbonate from 2 x 10 to 2 x 10 , - complexing compound/catalyst from 0.004 to 0.03. 10. Method as stated in claims 1 to 9, characterized in that the diallyl carbonate is transesterified under an inert atmosphere to diethylene glycol-bisallyl carbonate with the aid of diethylene glycol, the amount of reaction components used having the following molar ratio: - diethylene glycol/diallyl carbonate from 1/40 to 1/ 2, - catalyst/diethylene glycol from 2 x 10<-4> to 10<-2>' - complexing compound/catalyst from 0.001 to 0.1. 11. Method as stated in claim 10, characterized in that the amount of reaction components used has the following molar ratio: diethylene glycol/diallyl carbonate from 1/10 to 1/4, -4 -3 catalyst/diethylene glycol from 4 x 10 to 4 x 10 , complexing compound/catalyst from 0.004 to 0.03.