JPS6030302B2 - Production method of ester from nitrile - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to the production of carboxylic acid esters, and in particular to the production of aromatic carboxylic acids from nitriles.

According to the invention, the nitrile is reacted with water and a hydroxyl compound in the vapor phase in the presence of a catalyst suitable for converting the nitrile into a carboxylic acid ester, the reaction being carried out entirely in the vapor phase. That is, the starting material and the ester product are in the vapor phase. The organic nitriles used to produce esters according to the invention are aromatic or nitriles.

Aromatic nitriles contain one or more cyano groups, preferably one or two cyano groups, and can be substituted with other substituents such as alkyl, carboxyl or amido groups, or It can also be non-substituted. Preferably, the aromatic nucleus is benzene or naphthalene. Typical examples include phthalonitrile, terephthalonitrile, isophthalonitrile, benzonitrile,
Mention may be made of trinitrile, 1-cyanonaphthalene and 2,6-cyanonaphthalene, 2-, 3- or 4-cyanobenzoic acid, 2-, 3- or 4-cyanobenzamide, and the like. Preferred starting materials are isophthalonitrile, terephthalonitrile and phthalonitrile. If the nitrile contains a carboxy or amide substituent, such substituent is esterified with an alcohol and the cyano group is hydrolyzed and esterified to form a gester.

For example, methanol and 4-cyanobenzamide or 4-
The reaction between cyanobenzoic acid produces dimethyl terephthalate. The hydroxyl compound can be an alcohol or a phenol.

The alcohol is preferably an aliphatic hydrocarbon alcohol;
Particularly alkanols, preferably alkanols having 1 to 12 carbon atoms, most preferably alkanols having 1 to 4 carbon atoms. Methanol is most preferred. Representative examples of suitable alcohols include methanol, propanol, butanol, octanol, and the like. The alcohol is selected such that the ester formed is in the vapor phase at the reaction conditions. The catalyst used for the steam phase hydrolysis of the present invention is a solid acidic catalyst.

Typical catalysts include silica gel, silica alumina,
Supported phosphoric acids or shelf acids or mixtures thereof, group m metal phosphates and sulfates such as aluminum,
Mention may be made of phosphates and sulfates of shelf elements and gallium, transition metal oxides such as one or more of vanadine, chromium, manganese, iron, cobalt, nickel and the like. Catalysts are of the type used in hydration, dehydration and esterification reactions. The preferred catalyst is supported phosphoric acid alone or in a mixture with shelf acids. Nitriles, water and hydroxyl compounds are in the vapor phase, generally 1
49-48 is ○ (300-9000F), preferably 2
React at a temperature of 500-7000F.

The temperatures used are generally above the fog points of the feedstock and product components. Water is used in at least stoichiometric proportions (1 mole of water for 1 mole of cyano group); however, it is preferred to use an excess of water since the reaction thermodynamics and kinetics are more favorable at higher water pressures. .

The stoichiometric amount of water can be large enough to provide a water to nitrile molar ratio of 500:1 or less; generally the water to nitrile molar ratio is from 1:1 to 50:1. The hydroxyl compounds are used in at least stoichiometric proportions, ie at least 1 mole of hydroxyl compound per mole of nitrile group.

However, reaction kinetics and thermodynamics proceed more favorably at high hydroxyl compound partial pressures, so it is preferred to use an excess of hydroxyl compound. For practical reasons, the molar ratio of hydroxyl compound to nitrile is 50
Generally this ratio is between 5:1 and 50:1, kept below 0:1. When the hydroxyl compound has a high volatility, for example methanol, and when used in excess, it also serves the function of maintaining the vapor phase state. However, inert gaseous diluents such as nitrogen can be used for such purposes. The total reaction pressure is generally selected to provide the desired alcohol/water pressure, and such total pressure is generally from 1 to 1 p atm. Catalytic vapor phase reactions can be carried out in any one of a wide range of reaction techniques, including solid bed, fluidized bed, dilute phase transfer, etc., and selection of a particular method is within the skill of those skilled in the art from the teachings of this invention. think.

The gaseous reaction effluent contains as main components the aromatic carboxylic acid ester reaction product, ammonia, water vapor, unreacted starting material, and reaction intermediates such as amides and acids, and the starting material contains at least two cyano groups. If present, the reaction intermediates may further contain cyano-acids (e.g. 4-cyanobenzoic acid), cyanoamides (e.g. 4-cyanobenzamide), amido-acids (e.g. terephthalamic acid),
cyanesters (e.g. 4-cyanomethylbenzoate).

Unreacted starting materials (nitriles and alcohols) as well as reaction intermediates can be recovered and recycled to the reaction by methods known to those skilled in the art. Ammonia present in the effluent can be recovered and used to make nitrile starting material. The recovered product is a gestal when the starting material is dinitrile, cyanobenzoic acid or cyanobenzamide. The present invention will be further explained below with reference to Examples.

Example 1 A solid phosphoric acid catalyst was prepared using the method described in “The Catalyst” Vol. 1 by F.G. Chiavetta and C.J. Plank.
vol. 344 (published by Reinhold, 1954).

The outer diameter of the manufactured catalyst 50 was kept at 30,000 mm.
The mixture was charged into a vertical reactor made of 9-inch (reed-in) tubes.

Terephthalonitrile was heated and introduced into the reactor from a Fusen steel reservoir as a vapor accompanied by a stream of nitrogen. The nitrogen flow was adjusted to pass 0.126 g of terephthalonitrile (TPN) into the reactor for 1 hour. At the same time, a solution containing 5.3% by weight of water and 94.7% by weight of methanol was introduced into the reactor with a syringe pump at a rate of 3.06' per hour. The mixture was immediately vaporized. The residence time of the above reaction components in the reactor was 3 hours. The effluent was collected in a cold trap. After 3 hours at a reaction temperature of 300 oo, the contents in the cold trap were analyzed by liquid chromatography and found to contain 0.49 to 0.16 dimethyl terephthalate (DMT). . Example 2 The experiment of Example 1 was repeated except that the reactor was charged with a catalyst made by impregnating alumina spheres with 18.7% by weight of a mixture of Day3P04/Day3B03 in a 2 to 1 molar ratio.

The catalyst was treated with a vaporized 10% ammonia solution for 1 hour and then flushed with nitrogen before starting the experiment. TPN' was charged into the reactor at a rate of 0.82 m/hr, and a solution of 6 wt% water and 94.0 wt% methanol was charged at 3.06 m/hr.
It was prepared at the rate of hr.

The solution was immediately vaporized. The residence time of the above reaction components in the reactor was 3 hours. After 5 hours the cold trap contains 4.40 hours of product and the reaction temperature is 260q.
I found out that o.

Analysis by liquid chromatography showed that DMT was 0.75 μm.
, TPN of 1.46 pm and 4-cyanomethylbenzoate of 1.84 pm were confirmed. Excess methanol was recovered as dimethyl ether. The present invention is particularly advantageous in that aromatic carboxylic acid esters can be made without utilizing carboxylic acids or salts thereof as starting materials.
Carboxylic acids or salts, especially terephthalic acids or salts, are difficult to evaporate and therefore require complex equipment to carry out such evaporation. Furthermore, carboxylic acids are generally made from nitriles, which requires additional steps. According to the invention, hydrolysis and esterification can be carried out in a single reactor by carrying out them under mild conditions and in the vapor phase.

Claims (1)

[Scope of Claims] 1. The corresponding aromatic carboxylic acid ester, hydroxyl compound, and nitrile are prepared by reacting the nitrile with water and a hydroxyl compound in the vapor phase at a temperature above the dew point of the product aromatic carboxylic acid ester, hydroxyl compound, and nitrile in the presence of a solid acidic catalyst. A method for producing an aromatic carboxylic acid ester, which comprises producing a carboxylic acid ester. 2 Nitrile, phthalonitrile, terephthalonitrile, isophthalonitrile, benzonitrile, tolnitrile, 1-cyanonaphthalene, 2,6-cyanonaphthalene,
2. The method of claim 1, wherein the compound is selected from the group consisting of 2,3 or 4-cyanobenzoic acid, 2,3 or 4-cyanobenzamide, or mixtures thereof. 3. The method according to claim 2, wherein the hydroxyl compound is an alkanol having 1 to 12 carbon atoms. 4 The above reaction was carried out at 149-482°C (300-900°F).
) The method according to claim 3, which is carried out at a temperature of: 5
5. The method of claim 4, wherein the hydroxyl compound is methanol. 6. The method according to claim 5, wherein the nitrile is terephthalonitrile. 7 The above reaction was carried out at 266-371°C (500-700°F).
) The method according to claim 6, which is carried out at a temperature of: 8 Claim 7 in which the catalyst is supported phosphoric acid
The method described in section. 9. A method according to claim 8, wherein the phosphoric acid is in the form of a mixture with boric acid. 10. The method according to claim 4, wherein the hydroxyl compound is an alkanol having 1 to 4 carbon atoms. 11 The solid acidic catalyst is silica gel, silica-alumina,
Phosphoric acid, boric acid, phosphates or sulfates of group III metals,
and a transition metal oxide.