MXPA97009461A

MXPA97009461A - Process for the preparation of 3- (methylene) propanal and 2-hydroxy-4- (methylthy) butanonitr

Info

Publication number: MXPA97009461A
Application number: MXPA/A/1997/009461A
Authority: MX
Inventors: F Blackburn Thomas; F Pellegrin Paul; H Kranz Allen
Original assignee: Novus International Inc
Priority date: 1995-06-07
Filing date: 1997-12-03
Publication date: 1998-02-01

Abstract

The present invention relates to: Describes a catalytic process for the preparation of 3- (methylthio) propanal and 2-hydroxy-4- (methylthio) butanonitrile, using novel addition catalysts. The novel addition catalysts include: triisopropanlamin, nicotinamide, imidazole, benzimidazole, 2-fluoropyridine, picoline, pyrazine, trialkylamines having from three to eighteen carbon atoms in each of the alkyl substituents attached to the nitrogen atom, and tertiary amines having the formula (I), wherein A is aryl, R1 and R2 are alkyl, and x, a, b and c are integers such that 0 <- x < - 3, a < - a < - 3, 0 < - b < - 2, 0 < - c < - 2, provided that a + b + c

Description

PROCESS FOR. THE PREPARATION OF 3- (METHYL10) PROPANAL AND 2-HYDROXY-4- (METHYLTHY) BUTANONITRILE BACKGROUND OF THE INVENTION The present invention relates to catalytic processes for the preparation of 3- (methylthio) propanal (hereinafter "MMP") and 2-hydroxy-4- (methylthio) butanonitrile ("HMBN"). More particularly, the present invention relates to processes for preparing MMP and HMBN using novel addition catalysts. MMP and HMBN are intermediates for the manufacture of both d, 1-methionine and 2-hydroxy-4- (methylthio) butanoic acid ("HMBA"). Methionine is an essential amino acid commonly deficient in grains used in animal feed compositions. HMBA provides a source of methionine, and is widely used as a methionine supplement in animal feed formulations. MMP is produced by the catalytic reaction between acrolein and methyl mercaptan. In a conventional process for the preparation of MMP, liquid acrolein and methyl mercaptan are introduced into a reactor containing liquid phase MMP and a suitable organic base, which acts as a catalyst for the olefin / mercaptan addition reaction. The reaction takes place in the liquid phase. The conventional organic basic catalysts REF: 26226 for the reaction between acrolein and methyl mercaptan include amines such as pyridines, hexamethylenetetran and triethylamine. The olefin / mercaptan reaction catalyst is typically combined with an organic acid, such as acetic acid, to inhibit the polymerization of acrolein and improve the yield of the product. The HMBN is subsequently produced by the addition reaction between MMP and hydrogen cyanide, in the presence of a catalyst of the appropriate addition reaction, which may include the organic bases used to catalyze the reaction between acrolein and methylmercaptan. The methionine can be produced by reacting the HMBN with an excess of ammonia under high pressure, to produce 2-amino-4- (methylthio) butanonitrile, and subsequently hydrolyzing the product using a mineral acid to form the methionine. Alternatively, the methionine can be produced by reacting the MMP with ammonium carbonate, to form a hydantoin, and subsequently hydrolyzing the hydantoin with a base to form the methionine. The HMBA can be produced by hydrolyzing the HMBN using a mineral acid. Pyridine has proven to be an effective addition catalyst used in the preparation of both MMP and HMBN. However, it would be highly beneficial to identify catalysts of alternative effective addition reactions for the preparation of these valuable intermediates. BRIEF DESCRIPTION OF THE INVENTION Among the various objects of the present invention are the provision of a process for the preparation of MMP by the catalytic reaction between acrolein and methyl mercaptan; the provision of a process that provides a high MMP reaction yield; the provision of a process in which the degradation of MMP and the production of high molecular weight by-products remains at acceptably low levels; the provision of a process that can produce high quality MMP, which can be used directly, without the need for additional purification, in the preparation of methionine or HMBA; the provision of a process for the preparation of HMBN by the catalytic reaction between the reaction product of MMP and hydrogen cyanide; the provision of a process that provides a high HMBN reaction yield; and the provision of a process in which the catalyst remaining in the MMP reaction product can be subsequently used to catalyze the reaction between MMP and hydrogen cyanide to produce HMBN. Briefly, therefore, the present invention is directed to a process for the manufacture of MMP. The process comprises reacting methyl mercaptan with acrolein in a reaction zone, in the presence of a novel olefin / mercaptan addition reaction catalyst. The novel catalyst comprises at least one organic base selected from the group consisting of triisopropanolamine, tripropylamine, nicotinamide, imidazole, benzimidazole, 2-fluoropyridine, 4-dimethylaminopyridine, 4-dimethylaminopyridine, picoline, pyrazine, trialkylamines having from five to ten and eight carbon atoms in each of the alkyl substituents attached to the nitrogen atom, and tertiary amines having the formula: wherein A is aryl, Ri and R2 are alkyl and x, a, b and c are integers such that 0 <x < 3, 1 < a < 3, 0 < b < 2, 0 < c < 2, provided that a + b + c = 3. It has further been discovered that the novel olefin / mercaptan addition reaction catalyst used to catalyze the reaction between acrolein and methylmercaptan is also useful for catalyzing the reaction between MMP and cyanide. hydrogen to produce HMBN. Thus, the present invention is further directed to a process for the manufacture of HMBN, which comprises making reacting MMP with hydrogen cyanide in the presence of an addition reaction catalyst. The addition reaction catalyst comprises at least one organic base selected from the group consisting of triisopropanolamine, nicotinamide, imidazole, benzimidazole, 2-fluoropyridine, poly-4-vinyl-pyridine, 4-dimethylaminopyridine, picoline, pyrazine, trialkylamines having from three to ten and eight carbon atoms in each of the alkyl substituents attached to the nitrogen atom, and tertiary amines having the formula: [.-cc »,,,] - <;; wherein A is aryl, Ri and R2 are alkyl and x, a, b and c are integers such that 0 <x < 3, 1 < a < 3, 0 < b < 2, 0 < c < 2, provided that a + b + c = 3. According to another embodiment of the present invention, the novel addition catalyst described herein is used to first catalyze the reaction between methyl mercaptan and acrolein to produce a product mixture. of intermediate reaction comprising MMP and the novel catalyst. Then, without a previous separation of the MMP catalyst in the intermediate reaction product mixture, the MMP reaction product was it reacts with hydrogen cyanide to produce HMBN. Other objects and aspects of this invention will be in part apparent and in part signaled in the following. DETAILED DESCRIPTION OF THE PREFERRED MODALITIES According to the present invention, MMP is produced by the reaction between acrolein and methyl mercaptan in the presence of a novel olefin / mercaptan addition catalyst. The MMP in the reaction product mixture can then be reacted with hydrogen cyanide to produce HMBN, using the novel catalyst present in the MMP reaction product mixture as a catalyst of the addition reaction in the cyanidation reaction. The catalytic reaction between acrolein and methyl mercaptan to produce MMP is well known and, in the practice of the present invention, this reaction can be carried out in any suitable manner without particular limitation to the various process conditions employed. For example, acrolein vapor can be absorbed in a liquid reaction medium containing recycled MMP product. The acrolein absorbed in the liquid reaction medium is reacted with methyl mercaptan in the presence of a catalyst of the olefin / mercaptan addition reaction within the reaction zone of a suitable reactor. The methylmercaptan is added to the liquid reaction medium in an amount at least substantially stoichiometrically equivalent to the acrolein on a molar basis. A slight excess of methyl mercaptan can be used. Preferably, about 1 to about 1.02 moles of methyl mercaptan are introduced into the reaction zone for each mole of acrolein present in the liquid reaction medium. Methyl mercaptan and acrolein can be introduced into the liquid reaction medium either simultaneously or successively. The reaction catalyst of the olefin / mercaptan addition may be present either completely or partially in the MMP, or it may be introduced into the liquid reaction medium entirely or partially together with the acrolein and the methyl mercaptan. The temperature of the reaction is desirably maintained within the range of from about 30 to about 70 ° C. The reaction pressure is not critical, and can vary within wide limits. However, to simplify the reaction apparatus, it is preferred that the reaction be conducted at near atmospheric pressure, or at only moderately reduced or elevated pressure. The reaction between acrolein and methyl mercaptan can be conducted either continuously or discontinuously. In a batch process, acrolein in the form of vapor or liquid can be added to methyl mercaptan in substantially equivalent molar amounts. Alternatively, acrolein and methyl mercaptan can be simultaneously introduced in substantially stoichiometrically equivalent addition ratios in a liquid reaction medium comprising MMP. The reaction medium for a given batch is conveniently provided for a given batch leaving a residue of MMP in the reactor of a previous batch. Thus, the batch reactor can be operated in a semi-continuous mode, in which acrolein and methylmercaptan are introduced in a substantially constant proportion during a significant portion of the batch cycle, and the reaction product is periodically removed from the reactor. , leaving a residue for the next batch. Fully continuous processes are described, for example, in Biola, U.S. Patent No. 4,225,516, Hsu et al., U.S. Patent No. 5,352,837 and the co-pending, co-pending US Patent Application Serial No. 08 / 557,699, which are expressly incorporated herein by reference. As described in Hsu et al., The continuous reaction can be carried out by introducing acrolein vapor and methyl mercaptan into a fluid reaction medium of MMP, in either a concurrent contact zone or a gas / liquid countercurrent. Alternatively, the The initial reaction can be carried out in a stirred tank reactor having an external cooler through which the reaction mixture is circulated. If the reaction is not completed within the residence time provided in the initial gas / liquid contact zone, the reaction medium of MMP containing acrolein and unreacted methylmercaptan is sent to a second reactor (eg a reactor). flow plug or a tank containing the batch) for the completion of the reaction. Preferably, the reaction temperature of the reaction does not exceed about 70 ° C in any of the reaction zones. The olefin / mercaptan addition catalysts for the commercial production of MMP are preferably evaluated on the basis of several criteria, which include (1) the conversion and performance of MMP; (2) reaction kinetics; and (3) a tendency to catalyze unwanted side reactions, which produce high molecular weight by-products and decrease the purity of the product, both during the MMP reaction and during the subsequent storage of the MMP reaction product. Additionally, such catalysts are preferably useful to further catalyze the reaction between MMP and hydrogen cyanide to produce HMBN, such that the mixture of MMP reaction product containing the addition catalyst can be treated directly with hydrogen cyanide to produce HMBN, without interposed purification. It has been found that certain organic bases which previously have not been recognized as viable olefin / mercaptan addition reaction catalysts can advantageously be used to catalyze the reaction between acrolein and methyl mercaptan to form MMP. Accordingly, the novel catalysts of the present invention include at least one organic base selected from certain heterocyclic amines, trialkylamines and other tertiary amines in which one of the non-hydrogen substituents attached to the nitrogen atom of the tertiary amine contains a group aril. The novel olefin / mercaptan addition reaction catalysts may additionally comprise triisopropanolamine. The heterocyclic amines that may be present in the novel olefin / mercaptan addition catalyst of the present invention are selected from the group consisting of nicotinamide, imidazole, benzimidazole, 2-fluoropyridine, 4-dimethylaminopyridine, picoline (for example 2-picoline, 3-picoline and 4-picoline) and pyrazine. Trialkylamines that may be present in the olefin / mercaptan addition catalyst of the present invention are characterized in that they have at least three carbon atoms in each of the alkyl substituents attached to the nitrogen atom (eg, tripropylamine, tributylamine, etc.). However, the alkyl substituents should contain no more than about eighteen carbon atoms, so that the trialkylamine can be sufficiently soluble in the MMP reaction mixture. The alkyl substituents can be linear, branched or cyclic. To take advantage of the generally diminished flammability, toxicity and volatility provided by the higher molecular weight trialkylamines, and to avoid problems of solubility in the MMP reaction mixture, each of the alkyl substituents of the trialkylamines present in the olefin / mercaptan addition catalyst preferably contains from five to twelve carbon atoms (for example, tripentylamine, trihexylamine, triheptylamine, trioctylamine, trinonylamine, tridecylamine, triacecylamine, tridodecylamine, etc.). The novel olefin / mercaptan addition reaction catalysts of the present invention may additionally include certain other tertiary amines in which at least one of the non-hydrogen substituents attached to the nitrogen atom contains an aryl group (e.g., phenyl, naphthyl, etc.). More specifically, the aryl containing tertiary amine that can be used to catalyze the reaction between acrolein and methyl mercaptan has the formula: wherein A is aryl, Ri and R2 are alkyl and x, a, b and c are integers such that 0 <x < 3, 1 < a < 3, 0 < b < 2, 0 < c < 2, provided that a + b + c = 3. Suitable tertiary amines containing an aryl group for use in the present invention include triphenylamine, tribencylamine and N-methyldiphenylamine. Preferably, x > 1, such that there is at least one unit of -CH2- which separates the groups (s) from the nitrogen atom. According to a particularly preferred embodiment of the present invention, x > 1 and a = 2 (for example, N-methyldiphenethylamine and N-ethyl-3,3'-diphenyldipropylamine). Each of the amines mentioned above can suitably be used as an olefin / mercaptan addition catalyst in the commercial production of MMP. However, with reference to the evaluation criteria of the catalyst identified here, some of these Organic bases have shown superior overall performance and effectiveness than others. According to a more preferred embodiment of the present invention, the olefin / mercaptan addition catalyst comprises at least one amine selected from the group consisting of triisopropanolamine, imidazole, benzimidazole, picoline, N-methyldiphenethylamine, N-ethyl-3, 3 '-diphenyldipropylamine and trialkylamines having from five to twelve carbon atoms in each of the alkyl substituents attached to the nitrogen atom. Other organic bases can be used as the catalyst for the olefin / mercaptan addition reaction, for use in the preparation of MMP, including poly-4-vinylpyridine, t-octylamine, sodium nicotinamide and 3-fluoropridine. In addition to these organic base catalysts, certain salts can be used to catalyze the reaction between acrolein and methylmercaptan, including acetates, molybdates and alkali metal formats, either alone or in combination with a crown ether or an ammonium salt. quaternary to improve the solubility of the anion of the salt in the reaction mixture of MMP, and salts of ethylenediaminetetraacetic acid. Additionally, we have examined the use of other compounds, namely zinc acetate, zinc carbonate, p-toluenesulfonic acid, 4-aminobutyric acid and palladium chloride, as catalysts in the preparation of MMP. However, these other compounds are not particularly useful for catalyzing the reaction between acrolein and methylmercaptan and, in the case of p-toluenesulfonic acid and palladium chloride, they appear to be substantially inert to promote the MMP reaction. The catalyst of the olefin / mercaptan addition reaction must be present in the liquid reaction medium in an amount sufficient to effectively catalyze the reaction between acrolein and methyl mercaptan. For example, in a batch process, the molar ratio of the catalyst to methyl mercaptan charged to the reaction zone is from about 0.001 to about 0.02, preferably from about 0.001 to about 0.01, especially from about 0.001 to about 0.005. It should be noted that some of the novel olefin / mercaptan addition reaction catalysts described herein (for example, nicotinamide, imidazole, benzimidazole and poly-4-vinylpyridine) are solid at the reaction temperatures typical of MMP. If it is sufficiently soluble, such a solid catalyst can be employed suitably by dissolving the catalyst in the liquid reaction mixture of the MMP. If the catalyst is insufficiently soluble, a minimum amount of a suitable solvent (eg, water, organic or inorganic acid) can be added to the reaction mixture as an auxiliary of the solubility of the catalyst, or the catalyst can simply be suspended in the reaction mixture. However, to avoid the formation of a separate aqueous phase and possible adverse effects on the reaction between methylmercaptan and acrolein, the water content of the MMP reaction mixture is preferably controlled, so that it is no closer to 6% by weight, more preferably no more than about 3% by weight, and especially no more than about 1.5% by weight. Additionally, if a solid catalyst is employed, it may be advantageous to first dissolve the catalyst in a suitable solvent, to form a liquid premix of catalyst, to facilitate the addition of the catalyst to the reaction zone. The novel catalysts of the olefin / mercaptan addition reaction described herein are preferably combined with an organic or inorganic acid in the reaction zone. The presence of an acid is believed to moderate the basicity of the organic liquid reaction medium, thereby inhibiting the undesired base catalyzed side reactions, which decrease the quality of the MMP. On the other hand, the acid can improve the solubility of the solid catalyst in the liquid reaction mixture of MMP. A variety of organic acids, including acetic acid, can be used Formic, citric acid, short-chain fatty acid and organic sulfo-acids (for example, trifluoromethanesulfonic acid). Suitable inorganic acids include mineral acids such as sulfuric and phosphoric acid. Due to commercial availability and its relatively low cost, acetic acid is preferred. The molar ratio of organic base to acetic acid introduced into the reaction zone is typically from about 0.5 to about 2.0. Preferably, to ensure that the base-catalyzed side reactions are sufficiently inhibited, the molar ratio of organic base to acetic acid introduced into the reaction zone is from about 0.5 to about 1.0. When one or more of the bases mentioned above is combined in the reaction zone with a mineral acid, the mineral acid is preferably sulfuric acid or phosphoric acid. The molar ratio of the organic base to the mineral acid introduced in the reaction zone is preferably from about 1 to about 50. When one of the organic bases described herein is combined with an organic or inorganic acid in the reaction zone , the liquid reaction medium preferably contains from about 0.2% to about 0.75% by weight of the organic / acid base combination. To simplify the addition of the organic / acid base combination to the reaction zone, the catalyst may first be combined with an organic or inorganic acid, to form a liquid premix of catalyst, which is then added to the reaction zone. The MMP reaction product can be used directly for the preparation of HMBN without prior distillation for the elimination of either high-boiling or low-boiling impurities. This not only saves the capital and operating expense of the distillation, but also avoids the yield losses that inevitably result from the formation of additional high-boiling compounds in the distillation column of the MMP. The HMBN can be produced by reacting the reaction product of MMP with hydrogen cyanide in the presence of a suitable addition reaction catalyst. Advantageously, it has been discovered that triisopropanolamine, nicotinamide, imidazole, benzimidazole, 2-fluoropyridine, poly-4-vinylpyridine, 4-dimethylamino-pyridine, picoline and pyrazine can serve as catalysts of the addition reaction in the production of HMBN. Additionally, trialkylamines having from three to eighteen carbon atoms in each of the alkyl substituents attached to the nitrogen atom, and tertiary amines in which at least one of the non-hydrogen substituents attached to the nitrogen contain an aryl group, such as those described in The above can also be used to catalyze the reaction between MMP and hydrogen cyanide to produce HNBN. Thus, according to a preferred embodiment of the present invention, it is possible to first prepare MMP by reacting methyl mercaptan with acrolein in a reaction zone, in the presence of one of the olefin / mercaptan addition reaction catalysts described herein, and either alone or in combination with a suitable organic or inorganic acid, to produce a mixture of intermediate reaction product containing MMP and the catalyst. After this, and without a prior separation of the MMP catalyst in the intermediate reaction product mixture, the MMP can be converted directly to HMBN by reacting the MMP with hydrogen cyanide. In the case where the catalyst of the olefin / mercaptan addition reaction comprises a trialkylamine having from three to ten and eight carbon atoms in each of the alkyl substituents attached to the nitrogen atom, or a tertiary amine having an aryl group in at least one of the non-hydrogen substituents attached to the nitrogen atom, it is preferred to substantially immediately convert the MMP which is in the mixture of the intermediate reaction product to HMBN, to produce HMBN of high quality and high performance. The catalytic reaction between MMP and hydrogen cyanide to produce well-known HMBN and, in the practice of the present invention, this reaction can be carried out in any suitable manner without particular limitation to the various process conditions employed. The MMP product can be reacted with hydrogen cyanide in either a continuous reaction system or in batch form. Preferably, the hydrogen cyanide is present in a small molar excess, of about 2% relative to the MMP. The temperature of the cyanidation reaction is desirably maintained within the range of from about 30 to about 70 ° C, preferably from about 50 to about 70 ° C. As in the MMP reaction, the pressure maintained during the cyanidation reaction is not critical, and can vary within wide limits, but is preferably close to atmospheric pressure. Due to their general effectiveness as catalysts for both the olefin / mercaptan addition reaction and the reaction between MMP and hydrogen cyanide, the addition catalyst used to prepare HMBN in this manner preferably comprises at least one amine selected from the group consisting of of triisopropanolamine, imidazole, benzimidazole, picoline, poly-4-vinylpyridine, N-methyldiphenethylamine, N-ethyl-3,3'-diphenyldipropylamine and trialkylamines having from five to twelve carbon atoms in each of the alkyl substituents attached to the nitrogen atom . MMP and hydrogen cyanide must be reacted in the presence of a sufficient amount of addition catalyst to effectively promote the cyanidation reaction. For some catalyst systems, a larger amount of addition catalyst may be employed during the cyanidation reaction than is present during the reaction between acrolein and methyl mercaptan. Thus, an excess of addition catalyst can be used initially during the MMP reaction, to ensure that a sufficient amount of catalyst is present in the mixture of the intermediate reaction product to effectively catalyze the reaction between MMP and hydrogen cyanide. However, the use of an excess of addition catalyst in the reaction between acrolein and methylmercaptan to later achieve an optimal hydrogen cyanide addition can cause an excessive degradation of the MMP reaction product. In such cases, it is preferred that a further amount of an organic base catalyst is introduced into the mixture of the intermediate reaction product immediately bethe introduction of hydrogen cyanide, to further promote the cyanidation reaction. The catalyst added to the intermediate reaction product mixture can be selected from any of the addition catalysts described herein, and can, in fact, be the same catalyst used to catalyze the reaction between acrolein and methyl mercaptan. Alternatively, the aggregate catalyst may comprise a conventional organic base catalyst (e.g., pyridine, triethylamine, hexamethylenetetramine, etc.). Preferably, before the introduction of the additional catalyst, the concentration of the catalyst of the addition reaction in the mixture of the intermediate reaction product is between about 0.01% and about 1% by weight, more preferably between about 0.05% and about of 0.25% by weight, and after the additional amount of catalyst is introduced into the mixture of the intermediate reaction product, the intermediate reaction product mixture contains between about 0.05% and about 1% by weight, more preferably between about 0.1% and about 0.5% by weight of the addition catalyst. The HMBN produced by the process of the present invention can be converted directly without purification to HMBA, by any of the processes described in Ruest et al., US Patent No. 4,524,077 or the Hernández process, US Patent No. 4,912,257. In the Ruest patent process, the HMBN is hydrolyzed in sulfuric acid, the HMBA product is extracted from the hydrolyzed material using a solvent substantially insoluble in water, and the extract is steam distillated to produce 85% to 90% by weight of aqueous HMBA solution. In the process of the Hernández patent, the hydrolyzed material is neutralized with ammonia, it is caused to separate in two phases, the organic phase is evaporated and filtered to produce 85% to 90% by weight of aqueous HMBA solution. The present invention is illustrated by the following Examples, which are merely for the purposes of illustration, and should not be considered as limiting the scope of the invention or the manner in which it can be practiced. EXAMPLE 1 The following procedure was used in this Example to determine the performance of the proposed olefin / mercaptan catalyst for the reaction between acrolein and methyl mercaptan to produce MMP. The catalyst that was tested was mixed with acrolein, and an amount of this mixture was combined with an excess of methyl mercaptan in a 2 ml reaction flask with septum cap. The methyl mercaptan was transferred using Cooling with dry ice, both the vial with mercaptan and the reaction bottle. An excess of methyl mercaptan of about 5% to about 15% by weight, based on acrolein, was used. The amount of catalyst present in the reaction bottle was selected to provide about 0.0033 moles of catalyst per mole of acrolein or MMP product. In some tests, the catalyst was first combined with an organic or inorganic acid in a molar ratio of about 0.7 (catalyst to acid) and this catalyst / acid combination was then added to the acrolein. Also, water was sometimes added to the mixture that was in the reaction bottle, to improve the solubility of the catalyst. When a catalyst salt was used, this was sometimes combined with a crown ether or a quaternary ammonium salt in a molar ratio substantially equivalent to the salt, to improve the solubility of the catalyst. The reaction bottle containing the mixture was kept in an oven maintained at about 50 ° C. After about 30 minutes, the reaction bottle was removed, and reweighed to determine the weight loss during heating (usually less than about 0.002 g). The samples of the reaction mixture contained in the vial were analyzed by chromatography of gases, to make an analysis and to determine the amount of oligomers of high molecular weight present in the mixture. Table 1 contains a summary of the performance of the alternative aldehyde reaction catalysts, which were evaluated using the procedure described above. Control tests using pyridine and pyridine combined with acetic acid are included for comparison purposes. The criteria for evaluating the performance of the catalyst included the conversion of acrolein, the amounts of high molecular weight oligomers and the qualitative determination of the appearance of the appropriate chromatogram. Ideally, the MMP reaction mixture contained in the vial will show a low concentration of acrolein (indicating high conversion to MMP), low amounts of high molecular weight oligomers (indicating minimal side reactions), and a generally flat gas chromatography baseline (indicating the absence of other polymers). A material of poor quality will have a broad and pronounced maximum, which elutes several minutes after the aldehyde maximum, which does not always correlate with the oligomer concentrations. The work of gas chromatography-mass spectrometry has shown that this broad maximum is aldehyde, indicating that other components are they are breaking into the analysis to form this maximum.

Since an excess of methylmercaptan was used in this process, in yield the aldehyde was not considered a significant evaluation criterion. In Table 1, the baseline codes of gas chromatography (S), (M) and (U) indicate satisfactory, marginal and unsatisfactory, respectively. ND and tr indicate "not detected" and "traces", respectively. All values are reported in percent by weight. Table 1 MMP Catalyst Base line code Weight Oligomers of the assay by GC) Molecular Acrolein High Pyridine (S) 0.5 9.6 Pyridine / acetic acid (S) 0.1 0.1 Imidazole / acetic acid (S) tr 1.1 Imidazole / acetic acid ( S) 0.3 1.8 Benzimidazole / water / acetic acid (S) 0.2 1.0 Nicotinamide (U) 0.3 1.7 Nicotinamide (U) 0.9 6.5 Nicotinamide (U) 0.4 3.0 Nicotinamide / water (U) ND 0.2 Nicotinamide / water (U) 0.3 5.0 Nicotinamide / acetic acid (S) 5.2 Nicotinamide / acetic acid / water (S) 0.7 2.8 Nicotinamide / acetic acid / water (S) ND 4.0 Nicotinamide / water / sulfuric acid (U) 1.6 tr Nicotinamide / water / sulfuric acid (U) ND 5.0 Nicotinamide / water / sulfuric acid (U) 2.8 < 0.1 Nicotinamide / water / phosphoric acid (U) 0.5 4.4 Nicotinamide sodium (U) 14.6 Nicotinamide sodium / acetic acid (U) ND 4.9 Poly-4-vinylpyridine (U) 8.1 Poly-4-vinylpyridine / acetic acid (U) 0.1 1.2 Poly-4-vinylpyridine / acetic acid (U) 0.1 2.2 Poly-4-vinylpyridine / acetic acid (U) 0.1 Sodium acetate / 15-crown-5 (M) 2.0 24.8 Sodium acetate / chloride trioctylmethylammonium (U) 1.3 4.4 Sodium molybdate (U) 0.1 4.7 Sodium / acetic acid (U) 0.3 molybdate 7.5 Sodium formate (U) < 0.1 0.3 Disodium EDTA (U) 0.1 1.3 Disodium EDTA / acetic acid (U) ND 2.3 Palladium chloride (U) ND 0.3 p-Toluenesulfonic acid (U) ND 5.8 4-Aminobutyric acid (U) ND 2.3 4-Aminobutyric acid / acetic acid (U) ND 2.8 4-aminobutyric acid / acetic acid / water (U) ND 2.7 2-Fluoropyridine / acetic acid (S) 0.1 < 0.1 2-Fluoropyridine / acetic acid (U) 0.2 < 0.1 Tripropylamine / acetic acid / water (U) < 0.1 < 0.1 Tributylamine / acetic acid (U) < 0.1 0.5 Trifenylamine (U) < 0.1 < 0.1 Trifenylamine / acetic acid (U) < 0.1 0.2 Tribenzylamine (U) 0.2 < 0.1 Pyrazine / acetic acid (U) < 0.1 0.1 t-Octylamine / acetic acid (U) 0.2 2.0 4-Dimethylaminopyridine / acetic acid (S) < 0.1 0.5 4-Dimethylaminopyridine / acetic acid (S) 0.1 0.9 Zinc acetate (U) 0.4 0.4 Zinc carbonate (U) 0.3 < 0.1 EXAMPLE 2 The following procedure was used in this Example to determine the performance of triisopropanolamine and certain trialkylamines and tertiary amines containing a phenyl group as olefin / mercaptan catalysts for the reaction between acrolein and methyl mercaptan to produce MMP. In all tests, the catalyst that was tested was first combined with acetic acid in a molar ratio of about 0.7. However, in the case of tripropylamine, additional acetic acid (molar ratio of catalyst to acetic acid of 0.54) was added to achieve a single liquid phase. The catalyst / acetic acid combination was mixed with acrolein, and an amount of this mixture was combined with an excess of methyl mercaptan in a 2 ml reaction flask with septum cap. The methyl mercaptan was transferred using Cooling with dry ice of both, the vial of mercaptan and the vial of the reaction. An excess of methyl mercaptan was used from about 0.4% to about 9% by weight based on acrolein. The amount of catalyst present in the reaction bottle was selected to provide about 0.0033 moles of catalyst per mole of acrolein or MMP product. The reaction vial containing the mixture was kept in an oven maintained at about 50 ° C. After about 30 minutes, the reaction bottle was removed and reweighed to determine the weight loss during heating (usually less than about 0.002 g). The samples of the reaction mixture contained in the flask were analyzed by gas chromatography, to analyze them and to determine the amount of high molecular weight oligomers present in the mixture. Table 2 contains a summary of the performance of this group of alternative catalysts of the aldehyde reaction, which were evaluated using the procedure described above. The same criteria set forth in Example 1 in the present Example was used to evaluate the performance of the catalyst. In Table 2, the baseline codes for gas chromatography (S), (M) and (U) indicate satisfactory, marginal and unsatisfactory, respectively. All values are reported in percent by weight. Table 2 MMP Catalyst (Baseline Code Weight Oligomers from GC Assay) Molecular Acrolein High Triisopropanolamine / acetic acid (S) 0.1 0.1 Tripropylamine / acetic acid (S) 0.1 < 0.1 Tripentylamine / acetic acid (S) 0.1 < 0.1 Trioctylamine / acetic acid (S) 0.1 < 0.1 Tridodecylamine / acetic acid (S) 0.1 < 0.1 N-methyldiphenethylamine / acetic acid (S) 0.1 < 0.1 N-ethyl-3, 3 • -diphenyl-dipropylamine / acetic acid (S) 0.1 0.3 N-methyldiphenylamine / acetic acid (U) < 0.1 0.1 EXAMPLE 3 In this Example, a representative mixture of the MMP produced using tripropylamine combined with acetic acid to catalyze the reaction of the aldehyde was converted to HMBN by reacting it with hydrogen cyanide. A mixture of MMP was prepared by mixing water (0.091 g), distilled MMP (6.91 g) and a solution of tripropylamine / acetic acid catalyst (0.008 g) containing 0.54 moles of tripropylamine per mole of acetic acid. Hydrogen cyanide (40 μl, 99.5%) was added to 70 μl of this aldehyde / water / catalyst / acetic acid mixture in a reaction flask, using cooling with wet ice during transfer. The reaction bottle was then placed in an oven at 50 ° C for 30 minutes. The tripropylamine catalyst present in the MMP mixture was used to catalyze the cyanidation reaction. The vial was removed after the oven, and allowed to cool. A mixture of the cooled nitrile reaction product contained in the flask was analyzed by gas chromatography, for analysis, and to determine the amount of high molecular weight oligomers present in the mixture. The mixture contained 98.2% nitrile, 0.1% high molecular weight oligomers and 0.03% MMP on a weight basis.

EXAMPLE 4 In this Example, nicotinamide, imidazole, benzimidazole, 2-fluoropyridine, pyrazine and 4-picoline were tested, using the procedure described below to additionally determine their performance as olefin / mercaptan addition catalysts, for the reaction between acrolein and methylmercaptan. Distilled acrolein, which had a typical assay of about 97.3% to about 97.5% by weight of acrolein and about 2.5% by weight of water was mixed with hydroquinone to provide a mixture having a hydroquinone concentration of about 0.10% to about 0.12% by weight. The mixture of distilled acrolein and hydroquinone was stored at 0 to 5 ° C. Distilled methylmercaptan was used which had a typical assay of about 99.3% to about 99.5% by weight of methyl mercaptan. The reaction of the aldehyde was conducted in a 1000 ml stainless steel reactor with internal cooling coils for temperature control, and an agitator. An amount of MMP was first prepared by reacting acrolein and methyl mercaptan in the presence of a particular aldehyde catalyst. This MMP was then used as a "residue" to prepare a subsequent batch of MMP using the same catalyst. Typically, several batches of MMP were prepared using the same catalyst, and a MMP residue from the preceding batch, such that steady-state conditions were approached. To make the MMP residue, methyl mercaptan was charged to the reactor, followed by the catalyst, using a sub-surface feed tube. The reactor and its contents were heated to room temperature, and at that time the acrolein was fed to the reactor, for a period of about 25 minutes and at a temperature of about 50 ° C. About 1,005 moles of methyl mercaptan and about 0.0033 moles of catalyst were charged to the reactor per mole of acrolein. Except in the case of nicotinamide, the catalyst in the reactor was combined with acetic acid using a molar ratio of about 0.7 (catalyst to acetic acid). The reaction of the aldehyde was terminated by maintaining the process temperature at about 50 ° C, and stirring the reactor contents for about 60 minutes. Once the reaction of the aldehyde was complete, the reactor and its contents were cooled to 20 to 25 ° C for a period of about 10 minutes while stirring was continued. The catalyst (0.0033 moles per mole of acrolein) and, except in the case of nicotinamide, acetic acid (0.7 molar ratio of catalyst to acetic acid) were mixed with the MMP residue, and charged to the reactor for the preparation of additional aldehyde. The methyl mercaptan and the acrolein were then fed simultaneously to the reactor with stirring over a period of about 30 minutes, at a reaction temperature of about 60 ° C. Approximately 1,005 moles of methyl mercaptan per mole of acrolein were charged to the reactor. The aldehyde reaction was terminated by maintaining the process temperature at about 60 ° C for about 23 minutes. Once the reaction of the aldehyde was complete, the reactor and its contents were cooled to 20 to 25 ° C over a period of about 10 minutes. If necessary, the batch reaction sequence was repeated using a particular catalyst and an MMP residue from the appropriate batch until the steady-state conditions approached. A sample of the reaction mixture from the final batch was injected into a gas chromatograph for analysis. A sample of this reaction mixture was also subjected to analysis by gas chromatography to determine the amount of high molecular weight oligomers in the mixture. In some cases, limited studies of aging of the MMP reaction product were carried out to test the storage stability. Table 3 contains a summary of the performance of the alternative catalysts of the aldehyde reaction, the which were evaluated using the procedure described above. The results found in Table 3 include the percent by weight of methylmercaptan, acrolein, MMP and high molecular weight oligomers in the reaction mixture of the final batch. The results of a control test, using a pyridine catalyst combined with acetic acid are included for comparison purposes.

Table 3 Weight Oligomers Catalyst of MMP MeSH Acrolein MMP Molecular High Pyridine / acetic acid 0.30 0.23 97.88 1.25 Niootinamide 0.94 0.5 89.74 9.47 Imidazole / acetic acid 0.11 0.5 97.12 1.43 Benzimidazole / acetic acid / water 0.21 0.17 97.59 1.56 2-Fluorcpyridine / acetic acid 0.64 0.5 96.50 2.12 Pyrazine / acetic acid 0.30 0.23 97.88 2.19 4-picoline / acetic acid 0. 0.2211 0.38 98.02 1.14 Of the catalysts evaluated in this Example, nicotinamide, pyrazine, and 2-fluoropyridine produced MMP which had high levels or concentrations of high molecular weight oligomers. The MMP produced using imidazole, benzimidazole and 4-picoline as catalysts was tested for storage stability at 45 ° C. For comparison purposes, the MMP made using pyridine combined with acetic acid was also subjected to aging at 45 ° C to determine its storage stability. In a typical aging study, 40 g of the aldehyde product was placed in a glass bottle, which was then transferred to an oven maintained at 45 ° C. Periodically, samples of the product were removed from the bottle, and analyzed by gas chromatography for analysis. The results of the MMP aging study are submerged in Table 4. Table 4 Loss of MMP MMP Catalyst Days (% by weight of MMP / day) Pyridine / acetic acid 30 0.10 Imidazole / acetic acid 11 3.98 Benzimidazole / acetic acid 11 1.05 4-picoline / acetic acid 10 0.30 4-picoline / acetic acid 21 0.37 4-picoline / acetic acid 31 0.37 At 45 ° C, the MMP produced using imidazole, benzimidazole and 4-picoline as olefin / mercaptan addition catalysts showed more rapid deterioration compared to the aldehyde made using pyridine. MMP prepared using imidazole, benzimidazole and 4-picoline combined with acetic acid as olefin / mercaptan reaction catalysts were converted to HMBN by reacting it with hydrogen cyanide using the organic base catalyst that remained in the mixture of the MMP reaction product. to further catalyze the cyanidation reaction. For comparison purposes, the MMP prepared using pyridine / acetic acid as the catalyst was also converted to HMBN. The nitrile reaction was conducted in the same 1000 ml stainless steel reactor with agitator and internal cooling coils for temperature control. The MMP charge containing the organic base catalyst is first weighed into the reactor. Then the hydrogen cyanide (99.5%) was fed to the reactor with stirring over a period of 26 minutes, at a temperature of about 60 ° C. Approximately 1.02 moles of hydrogen cyanide per mole of MMP were charged to the reactor. The nitrile reaction was terminated by maintaining the batch without stirring or cooling for about 20 minutes. Once that the nitrile reaction was complete, the reactor and its contents were cooled to 20 to 25 ° C for a period of about 10 minutes. A sample of the reaction mixture was subjected to analysis by gas chromatography to determine its content, MMP and oligomer content. The results of the nitrile conversion are summarized in Table 5. Table 5 Weight Oligomers Catalyst HMBN MMP HMBN Molecular High Pyridine / acetic acid ND 98.5 0.7 I idazole / acetic acid tr 98.3 1.2 Benzimidazole / acetic acid ND 94.7 1.3 4-picoline / acetic acid ND 99.3 0.7 EXAMPLE 5 Distilled acrolein and methylmercaptan were used to prepare an MMP residue and a batch following the manner of Example 4. Poly-4-vinylpyridine, supplied by Reilley (Reillex 425) was used as the catalyst for the olefin addition reaction. mercaptan. Poly-4-vinylpyridine (2.7 g) was charged to the vacuum reactor. Methylmercaptan (88.4 g) was then charged to the reactor. The reactor and its contents were heated to room temperature, and in that At this time, acrolein (100.9 g) was fed to the reactor over a period of about 50 minutes at a reaction temperature of about 50 ° C. The reaction of the aldehyde was terminated as described in Example 4. Without further addition of the catalyst, methylmercaptan (196.1 g) and acrolein (235.9 g) were then fed simultaneously to the reactor with stirring, over a period of about 50 minutes, to a reaction temperature of about 50 ° C. The aldehyde reaction was terminated by maintaining the process temperature at about 50 ° C for about 30 minutes. A sample of the batch reaction mixture was subjected to analysis by gas chromatography. The analysis showed 89.9% MMP, 0.4% acrolein, 0.8% methylmercaptan, and 0.02% pyridine on a weight basis. The MMP product containing the poly-4-vinylpyridine catalyst was converted to the nitrile in the same reactor following the manner of Example 4. Hydrogen cyanide (155.4 g) was fed to the reactor containing MMP (600.0 g) with stirring during a period of about 50 minutes at a temperature of about 50 ° C. The nitrile reaction was terminated by maintaining the batch without agitation or cooling for about 30 minutes. Once the nitrile reaction was complete, the reactor and its contents were cooled to 20-25 ° C over a period of about 10 minutes. A sample of the nitrile reaction mixture was subjected to analysis by gas chromatography. The analysis showed 72.9% of HMBN and 2.6% of MMP on a weight basis. In view of what has been described above, it will be seen that the various objects of the invention are achieved. Since several changes could be made in the process described above without departing from the scope of the invention, it is proposed that all matter contained in the above description be interpreted as illustrative and not in a limiting sense.

It is noted that in relation to this date, the best method known to the applicant to carry out the aforementioned invention, is that which is clear from the present description of the invention.

Having described the invention as above, property is claimed as contained in the following:

Claims

RESINS 1. A process for the manufacture of 3- (methylthio) propanal, characterized in that it comprises reacting methyl mercaptan with acrolein in a reaction zone, in the presence of an olefin / mercaptan addition reaction catalyst, the catalyst comprises at least an organic base selected from the group consisting of triisopropanolamine, tripropylamine, nicotinamide, imidazole, benzimidazole, 2-fluoropyridine, 4-dimethylaminopyridine, picoline, pyrazine, trialkylamines having from five to eighteen carbon atoms in each of the attached alkyl substituents to the nitrogen atom, and tertiary amines that have the formula:

[A-teH > '-t; "> where A is aryl, R: and R2 are alkyl, and x, a, b and c are integers such that 1 = x = 3, 1 = a = 3, 0 = b = 2, O = c =
2, provided that a + b + c = 3. 2. A process according to claim 1, characterized in that a-2.
3. A process according to claim 2, characterized in that the catalyst of the addition reaction of olefin / mercaptan comprises at least one base organic selected from the group consisting of triisopropanolamine, picolina, N-metildifenetilamina, N-etil-3, 3'-difenildiproilamina and trialkylamines having from five to twelve carbon atoms in each of the alkyl substituents attached to the nitrogen atom.
4. A process according to claim 3, characterized in that the catalyst of the olefin / mercaptan addition reaction comprises N-methyldiphenethylamine.
5. A process according to claim 4, characterized in that the catalyst of the olefin / mercaptan addition reaction is combined with an organic acid in the reaction zone.
6. A process according to claim 3, characterized in that the catalyst of the olefin / mercaptan addition reaction comprises N-ethyl-3,3'-diphenyldipropylamine.
7. A process according to claim 6, characterized in that the catalyst of the olefin / mercaptan addition reaction is combined with an organic acid in the reaction zone.
8. A process according to claim 3, characterized in that the molar ratio of organic base to Methyl mercaptan introduced into the reaction zone is from about 0.001 to about 0.02.
9. A process according to claim 8, characterized in that the catalyst of the olefin / mercaptan addition reaction is combined with an organic acid in the reaction zone.
10. A process according to claim 9, characterized in that the organic acid is acetic acid, and the molar ratio of the organic base to the organic acid introduced in the reaction zone is from about 0.5 to about 2.0.
11. A process according to claim 10, characterized in that the reaction zone contains a liquid reaction medium comprising 3- (methylthio) propanal and the catalyst, the liquid reaction medium contains between about 0.2% and about 0.75. % by weight of the catalyst / organic acid combination.
12. A process according to claim 8, characterized in that the catalyst of the olefin / mercaptan addition reaction is combined with a mineral acid in the reaction zone.
13. A process according to claim 12, characterized in that the mineral acid is selected from the group consisting of sulfuric acid and phosphoric acid, and the molar ratio of the catalyst of the olefin / mercaptan addition reaction to the mineral acid introduced into the reaction zone is from about 1 to about 50.
14. A process according to claim 13, characterized in that the reaction zone contains a liquid reaction medium comprising 3- (methylthio) propanal and the catalyst, the liquid reaction medium contains between about 0.2% and about 0.75% by weight of the catalyst / organic acid combination.
15. A process for the manufacture of 2-hydroxy-4- (methylthio) butanonitrile, characterized in that it comprises reacting methyl mercaptan with acrolein in a reaction zone, in the presence of an olefin / mercaptan addition reaction catalyst, comprising at least one organic base selected from the group consisting of triisopropanolamine, tripropylamine, nicotinamide, imidazole , benzimidazole, 2-fluoropyridine, 4-dimethylaminopyridine, picoline, pyrazine, trialkylamines having from five to eighteen carbon atoms in each of the alkyl substituents attached to the nitrogen atom, and tertiary amines having the formula: [* - "" • '»] - < > ! where A is aryl, Ri and R2 are alkyl, and x, a, b and c are integers such that l = x = 3, l = a = 3, 0 = b = 2, O = c = 2, provided that a + b + c = 3, thereby producing a mixture of intermediate reaction product comprising 3- (methylthio) propanal and the catalyst; and without prior separation of the 3- (methylthio) propanal catalyst from the intermediate reaction product mixture, reacting 3- (methylthio) propanal with hydrogen cyanide, to produce 2-hydroxy-4- (methylthio) butanonitrile.
16. A process in accordance with the claim 15, characterized in that a = 2.
17. A process in accordance with the claim 16, characterized in that the catalyst of the olefin / mercaptan addition reaction comprises at least one organic base selected from the group consisting of triisopropanolamine, picoline, N-methyldiphenethylamine, N-ethyl-3,3'-diphenyldiprolamine and trialkylamines having from five to twelve carbon atoms in each of the alkyl substituents attached to the nitrogen atom.
18. A process in accordance with the claim 17, characterized in that the catalyst of the olefin / mercaptan addition reaction comprises N-methyldiphenethylamine.
19. A process according to claim 18, characterized in that the catalyst of the olefin / mercaptan addition reaction is combined with an organic acid in the reaction zone.
20. A process according to claim 17, characterized in that the catalyst of the olefin / mercaptan addition reaction comprises N-ethyl-3,3'-diphenyldipropylamine.
21. A process according to claim 20, characterized in that the catalyst of the olefin / mercaptan addition reaction is combined with an organic acid in the reaction zone.
22. A process according to claim 17, characterized in that the catalyst of the olefin / mercaptan addition reaction is combined with acetic acid in the reaction zone.
23. A process according to claim 17, characterized in that a further amount of an organic base is introduced into the intermediate reaction product mixture, to promote the reaction of 3- (methylthio) propanal with hydrogen cyanide.
24. A process according to claim 23, characterized in that the organic base introduced into the intermediate reaction product mixture comprises minus one organic base selected from the group consisting of triisopropanolamine, picoline, N-methyldiphenethylamine, N-ethyl-3, 3f-diphenyl dipropylamine and trialkylamines having from five to twelve carbon atoms in each of the alkyl substituents attached to the atom of nitrogen.
25. A process according to claim 23, characterized in that the organic base introduced into the intermediate reaction product mixture is the same organic base comprising the olefin / mercaptan addition reaction catalyst used to react the methyl mercaptan with acrolein.
26. A process according to claim 23, characterized in that the organic base introduced into the intermediate reaction product mixture is pyridine.
27. A process according to claim 23, characterized in that before the introduction of the additional amount of an organic base, the intermediate reaction product mixture contains between about 0.01% and about 1% by weight of the organic base , and after the additional amount of an organic base is introduced into the intermediate reaction product mixture, the intermediate reaction product mixture contains between about 0.05% and about 1% by weight of the organic base.