DE1134665B - Process for the production of vinyl esters - Google Patents

Description

GERMAN

PATENT OFFICE

F 28029 IVb / 12 ο

REGISTRATION DATE: MARCH 25, 1959

NOTICE
THE REGISTRATION
AND ISSUE OF THE
EDITORIAL: AUGUST 16, 1962

It is known that the production of vinyl esters can be carried out by reacting carboxylic acids with acetylene by two different methods. One method is that acetylene is added to carboxylic acids in the liquid phase in the presence of a catalyst at elevated temperature and at pressures up to about 25 atmospheres can act. In contrast, the second method works in the gas phase by a mixture of carboxylic acid vapor and acetylene at an elevated temperature over a catalyst is directed. The first-mentioned process has compared to vinylation in the gas phase Advantage of the more general applicability, since, for example, also difficult to evaporate or not undecomposed to evaporate Carboxylic acids, optionally in the form of their solutions, are reacted with acetylene can. The particular disadvantages of this process are that it is more satisfactory to achieve Results the application of higher pressures is required, thereby increasing energy and plant costs develop. The continuous implementation of this process also requires a considerable amount technical effort. In contrast, the vinylation of carboxylic acids in the gas phase is on an industrial scale and can be carried out continuously, as shown in particular using the example of vinyl acetate became. However, experience has shown that this process, which operates in the gas phase, can be used limited to a few carboxylic acids. The reasons for this are of various kinds. For example the resistance of the carboxylic acids and the vinyl ester to the evaporation and / or Vinylation of the acid required elevated temperatures of crucial importance. Therefore gas-phase vinylation is known to be particularly suitable for the preparation of vinyl esters of some saturated fatty acids. Processes for the production of vinyl benzoate are also in the gas phase has been described. However, these processes have not acquired any technical importance, since the vinyl benzoate under the conditions of its formation is partially pyrolytic with formation decomposed by acetophenone, which has a boiling point similar to vinyl benzoate and therefore Can be separated extremely difficult, so that in this way no pure vinyl benzoate can be produced. In addition, vinyl benzoate tends to vinylate benzoic acid In the gas phase required high temperatures for polymerization, so that the reaction vessel (contact space) through polymeric products

Process for the production of vinyl esters

Applicant:

Farbwerke Hoechst Aktiengesellschaft formerly Master Lucius & Brüning,

Frankfurt / M., Brüningstr. 45

Dr. Hans Fernholz, Bad Soden (Taunus),

Dr. Klaus Heimann-Trosien,

Frankfurt / M.-Unterliederbach,

and Dr. Hans-Joachim Schmidt, Frankfurt / M.,

have been named as inventors

clogged and a continuation of the process can be prevented.
A surprisingly simple process has now been found by means of which the essential difficulties which have hitherto stood in the way of a more general applicability of gas-phase vinylation are overcome. The process of the invention is characterized in that the acid to be vinylated is evaporated together with an entrainer, advantageously in a gas stream of acetylene, and the resulting vapor mixture of acid and entrainer is evaporated together with acetylene over one of the customary catalysts at temperatures above 150 ° C and conducts below the decomposition point of the carboxylic acid. The vinyl ester can then be isolated and purified in a known manner, for example by distillation. Suitable entrainers are those substances which can be distilled without decomposition at normal pressure and are chemically inert to carboxylic acids, acetylene and vinyl esters under the reaction conditions and which form azeotropic mixtures with the acid to be vinylated and / or their boiling point

4.5 at normal pressure no more than 40 ° C below or above the boiling point of the vinyl to be used Carboxylic acid. Such entrainers are z. B. aliphatic, cycloaliphatic, alkyl aromatic or aromatic hydrocarbons whose halogen

Compounds, ethers, ketones, esters of the acid to be vinylated that contain no reactive groups, such as Petroleum fractions, hexane, dean, dodecane, tri-

209 630/277

dean, tetradecane, diphenylmethane, diphenylpropane, Benzene, toluene, xylene, cumene, cymene, mesitylene, durol, diphenyl, pentamethylbenzene, 1- or 2-ethylnaphthalene, 1,6-dimethylnaphthalene, 1,5-dichloro

lysers or mixed catalysts into consideration, such as activated carbon, aluminum oxide, pumice stone or silica gel applied zinc and / or cadmium salts, optionally with

or -dibromopentane, tetrabromethylene, chlorine- 5 mercury salts are activated. Suitable for example

benzene, bromobenzene, o-, m- or p-dibromo or the salts of the acids to be esterified. To

Dichlorobenzene, 1-chloronaphthalene, dioxane, tetrasolution of the acid with acetylene is generally used

hydrofuran, diethylene glycol dimethyl, diethyl or at temperatures above 150 ° C and below

-dibutyl ether, triethylene glycol diethyl ether, tetra- the decomposition point of the acid among the other

Ethylene glycol dimethyl ether, diphenyl ether, 1- or ₁₀ applied reaction conditions worked. These

2-naphthol methyl ether, diisobutyl ketone, aceto temperatures depend partly on the type of

phonone, 4-methoxyacetophenone, propiophenone, the catalyst used. Generally works

Butyrophenone, the ethyl, propyl, butyl, isobutyl one at 170 to 400 "C, preferably at 180 to

or isoamyl ester of the acid to be vinylated. 320 ° C. Accordingly, such carbon

When carrying out the process of the invention, ₁₅ acids are considered, which boil at temperatures below 400 ° C, preferably below 360 ° C, carboxylic acid and entrainer, or use in the form of their mixtures or solutions, a vapor pressure sufficient for the vinylation the use of liquid mixtures or have. Particular advantages of the fiction, solutions generally the advantage of one modern method in Gasphasenvinylierung fächeren handling, such as the precise dosage _ao such carboxylic acids tion at normal temperatures, has what is especially true in highly resistant, under normal pressure boil above 200 ° C, or carboxylic acids which do not melt without decomposition cannot be distilled without decomposition and / or applies. In general, it is expedient to use their undiluted vinyl esters in the mixtures or solutions for the vinylation which, depending on the temperature required for the carboxylic acid, can easily polymerize at most 10 parts by weight of carboxylic acid, preferably at most. Such carboxylic acids, no more than 5 parts by weight of entrainer, are z. B. formic acid, capric acid, ethoxyacetic acid. However, you can also use mixtures or acid, is-butoxypropionic acid, bromoacetic acid, solutions which contain more than 10 parts by weight of α- or / 3-bromopropionic acid, mono-, di- or tri-entrainer, if this is generally chloroacetic acid, α- or / 8-chloropropionic acid, acrylic hose does not have any particular advantages. 30 acid, methacrylic acid, vinyl acetic acid, /?, /? - Dime-The composition of such mixtures is based on thylacrylic acid, crotonic acid, jS-chloroisocrotonic acid, essentially according to the properties of tiglic acid, sorbic acid, levulinic acid, α-ethyl carboxylic acid and the vinyl ester. If it is crotonic acid, benzoic acid, o-, m- or p-toluyl, for example, an acid which, in undiluted acid, 2-ethylbenzoic acid, 2-chlorine or bromine form, for vinylation in the gas phase 35 benzoic acid, 2.5 -Dichlorobenzoic acid, 2,4- or required temperatures is unstable, and 2,5-dimethylbenzoic acid, anisic acid, cuminic acid, or or a particularly polymerization phenylacetic acid, phenoxyacetic acid, hydrocinnamon-friendly vinyl ester, it is advantageous to use the acid, hexahydrobenzoic acid, salicylic acid To choose the cinnamon mixing ratio so that the acid, pyrocucic acid, thiophene-carboxylic acid- (2). thinning of the carboxylic acid by the entrainer ₄₀ To clean the acid and / or vinyl ester produced without particular difficulty or a polymerisation of the vinyl ester in the reaction by distillation and to prevent the entrainment vessel. In order to avoid such undesirable medium or consisting of entrainer and not environmentally and operatively interfering side reactions in yet Set acid mixture as a distillation Better way of invention provides the ₄₅ to recover the residue, and the process again method according to the possibility of being able additional implement, it is advantageous to a tow measure, which consists in that the mixture from
Carboxylic acid and entrainer lower in the presence
Quantities, e.g. B. 0.01 to 4%, preferably 0.04 to
2% based on the weight of the carboxylic acid ₅₀
Entrainer mixture, a suitable stabilizer is evaporated. Suitable as such
for example polymerisation-preventing substances
phenolic type, such as hydroquinone, catechol,

Hydroquinomethyl ether, 2-methylhydroquinone, ₅₅ benzoic acid boils at 249 ° C, melts at 121.7 ° C

4-methyl-2,6-di-tert-butylphenol, thymol. and sublimates at 100 ° C. Because of their sublimation

In general, it is recommended that the evaporation capability is an exact dosage of the undiluted carboxylic acid-entrainer mixture in counter-benzoic acid and thus a uniform use of acetylene, preferably in the for evaporation as well as a reaction with the for the success of the vinylation Acid required amounts to carry out 6 ₀ decisive, controllable reaction procedure. It is advantageous, albeit extremely difficult, so that it would also not be necessary to add acetylene in excess and would require considerable technical effort, namely in a ratio of 1 mol. These difficulties are exacerbated by the acid in 2 to 30, preferably 8 to 23 moles of acetylene. Process according to the invention in a simple manner The excess, unconverted acetylene can be eliminated. If you mix benzoic acid with one of the circulated back into the process. Suitable as an entrainer according to the invention. The catalysts for vinylation are substances such as butyl benzoate, which boils at 248 ° C. under normal conditions in the gas phase.

medium, whose boiling point at normal pressure is at least 10 ° C above the boiling point of the Cherishes vinylesters.

To further describe the method of the invention and its advantages over previous ones The gas phase vinylation process can be traced back to the example of the preparation of vinyl benzoate draw in. According to the literature

using equal parts by weight of benzoic acid and ßenzoic acid butyl ester a mixture that at about 90 ° C is present as a liquid solution, from which even at temperatures above 100 ° C no or only insignificant Amounts of benzoic acid sublime, allowing accurate dosing in the same simple manner can be carried out as with a liquid, low-boiling carboxylic acid. Will this mixture in one Gas stream of 9 to 18 moles of acetylene per mole of benzoic acid evaporated at about 200 ° C and at 210 to 230 ° C passed over a catalyst, for example zinc acetate applied to activated carbon, in this way, conversions of 64 to 87% of vinyl benzoate, based on the mixture, are obtained with a single passage on the amount of benzoic acid used. There is a clogging of the reaction vessel due to polymerized Vinyl benzoate or a premature decrease in the activity of the catalyst not to fear. The vinyl benzoate obtained after distillation is free from acetophenone and can be used to manufacture valuable polymerisation products without further cleaning will. The resulting as distillation residue solution of unreacted benzoic acid and Butyl benzoate can be fed back into the process after new benzoic acid has been added. The yields of vinyl benzoate are practically quantitative.

For the preparation of vinyl benzoate by the process according to the invention are as Entrainer instead of butyl benzoate z. B. the above substances are suitable, insofar as they meet the boiling point condition required according to the invention.

It is already known to present vinyl esters from carboxylic acids and acetylene in the vapor phase to produce the esters in question. However, the vinyl esters formed according to that process are In contrast to the substances to be used according to the invention, not compared to the starting substances inert because they are e.g. B. can react with carboxylic acids to form ethylidene compounds.

It is also known that one can produce Ameisensäurevinylester from acetylene and formic acid in the presence of acetic anhydride in the form of vapor at 150 to 26O ⁰ C. The amount of acetic anhydride in this known process is such that at least the water contained in the formic acid is completely converted. In this case too, the added reagent is accordingly not inert towards the starting materials. The acetic anhydride is also not inert to the reactants as it is, for. B. is reacted with formic acid to form a mixed anhydride.

example 1

In a gas stream of 300 liters of acetylene per hour, 300 g of an hourly benzoic acid and butyl benzoate are made up of equal parts by weight and evaporated to 100 ° C mixture at 200 ° C and at 220 ° C over 2 l of one passed through the application of zinc acetate on activated carbon prepared catalyst. The resulting Vinyl ester is condensed together with the entrainer and unreacted benzoic acid deposited. The unreacted acetylene is recycled back into the process.

From the condensate, which in addition to butyl benzoate 35 to 39% vinyl benzoate and 15 to 19% unchanged benzoic acid is obtained by vacuum distillation at 10 mm of mercury separated and purified vinyl esters passing between 83 and 89 ° C. That as distillation residue The resulting mixture of benzoic acid and butyl benzoate is added after the spent benzoic acid returned to the process. After 5 days, 19,860 g of vinyl benzoate are obtained and 1590 g of unchanged benzoic acid mixed with butyl benzoate from 18 108 g Benzoic acid obtained.

Example 2

In the same way as in Example 1, 300 liters of acetylene and 200 g of the mixture are added per hour of benzoic acid and butyl benzoate passed over the zinc-carbon contact at 230 ° C. To 37 days, 89.3 kg of benzoic acid become 106.7 kg of vinyl benzoate and 750 g of unchanged benzoic acid (in butyl benzoate).

Example 3

In an acetylene stream of 451 per hour, 70 g of 1 part by weight are produced per hour Benzoic acid and 2 parts by weight of a hydrocarbon mixture boiling at 230 to 250 ° C (petroleum fraction) existing and heated to 120 ° C solution evaporated at 260 ° C and over at 280 ° C 0.21 of a catalyst produced by impregnating pumice stones with cadmium acetate. After 10 hours, 207 g of vinyl benzoate are obtained in addition to unchanged benzoic acid.

Example 4

As indicated in Example 3, 68 g per hour of a solution evaporated at 265 to 270 ° C from 1 part by weight of p-toluic acid and 2 parts by weight Diphenyl ether and 461 acetylene passed over 0.21 of the cadmium-pumice stone contact at 280 ° C. After 28 hours, 595 g of vinyl p-toluate were formed.

Example 5

In the same way as indicated in Example 3, 461 acetylene and 50 g of one per hour are made

1 part by weight of o-chlorobenzoic acid and 2 parts by weight of diphenylmethane existing mixture 280 ° C passed over 0.21 of the cadmium catalyst. After 5 hours, 82 g of vinyl o-chlorobenzoate are obtained obtain.

Example 6

77 g of one from 1 part by weight of cinnamic acid and

2 parts by weight of a petroleum fraction boiling at 260 to 270 ° C, heated to 160 ° C Solution are evaporated hourly in a stream of acetylene of 601 per hour at 265 ° C and passed over the catalyst described in Example 3 at 280.degree. After 6 hours it is 128 g Cinnamic acid vinyl ester was formed.

Example 7

In a stream of acetylene of 300 liters per hour, 9.7 kg of one are removed within 32 hours 1 part by weight of sorbic acid, 2 parts by weight of diethylene glycol dibutyl ether and 0.03 part by weight

Hydroquinone existing solution evaporated at 220 ° C, passed at 230 ° C over 21 of the zinc-carbon catalyst mentioned in Example 1 and condensed. In addition to unchanged starting materials, the condensate contains 2.58 kg of vinyl sorbate (bp ₆ = 64 ° C).

Example 8

50 g of a mixture consisting of equal parts by weight of crotonic acid and acetophenone Evaporated hourly in a stream of 701 acetylene per hour at 190 ° C and at 200 to 210 ° C over 0.21 of the contact specified in Example 1 passed. After 6 hours there are 156 g of vinyl crotonate developed. When replacing acetophenone with o-dichlorobenzene as an entrainer you get similar sales.

Example 9

In an acetylene of 701 per hour are 30 g of a mixture of equal parts by weight of formic acid and diethyl ketone solution at 140 ° C is evaporated, at 180 ⁰ C for 0.21 of the mentioned in Example 1, carbon-zinc contact guided and condensed. After 8 hours, the condensate contains, in addition to unchanged starting materials, 139 g of vinyl formate.

Example 10

In an acetylene flow of 300 liters per hour 8.5 kg of a 50% solution of ß-butoxypropionic acid in a hydrocarbon mixture (petroleum fraction) boiling at 220 to 230 ° C is evaporated at 200 ° C and passed at 230 ° C. over 21 of the catalyst mentioned in Example 1. It will be 4.1 kg ß-Butoxypropionic acid vinyl ester (bp 5 = 67 ° C) and 0.7 kg of unchanged / 3-butoxypropionic acid dissolved in the hydrocarbon was obtained.

Example 11

In a stream of acetylene of 50 liters per hour, 38 g of a 50% solution of Chloroacetic acid evaporates in ethylene glycol dibutyl ether at up to 190 ° C and at 210 ° C above 0.21 of the catalyst mentioned in Example 1 passed. After 7 hours there are 146 g of vinyl chloroacetate developed.

Claims (4)

PATENT CLAIMS: 1. A process for the preparation of vinyl esters by reacting carboxylic acids with acetylene in the gas phase in the presence of a catalyst, characterized in that the carboxylic acid is evaporated together with an entrainer which is inert towards carboxylic acids, vinyl esters and acetylene and which can be distilled undecomposed under atmospheric pressure and which, with the carboxylic acid forms an azeotropic mixture and / or boils at most 40 ° C below or above the boiling point of the carboxylic acid, and passes the vapor mixture together with acetylene at temperatures above 150 ° C and below the decomposition point of the carboxylic acid over a catalyst and then isolates the vinyl ester formed. 2. The method according to claim 1, characterized in that mixtures or solutions evaporated from carboxylic acid and entrainer, which per part by weight of carboxylic acid does not exceed 10, preferably contain a maximum of 5 parts by weight of entrainer. 3. The method according to claim 1 and 2, characterized in that there is an entrainer used that at normal pressure at least 10 ° C above the boiling point of the carboxylic acid corresponding vinyl ester boils. 4. The method according to claim 1 to 3, characterized in that the carboxylic acid-entrainer mixture in the presence of a polymerisation inhibitor in amounts of 0.01 to 4%, preferably 0.04 to 2% of the amount by weight of the mixture evaporated. Considered publications:
Swiss patent specifications No. 239 537, 960;
U.S. Patent No. 2,682,556. © 209 630/277 &.