DE1271706B - Process for the continuous production of halogenated aliphatic vinyl esters - Google Patents

Description

FEDERAL REPUBLIC OF GERMANY

GERMAN

PATENT OFFICE

EDITORIAL

Int. α .:

C 07c

German class: 12 ο -19/03

Number: 1271706

File number: P 12 71 706.5-42 (C 25982)

Filing date: January 12, 1962

Open date: 4th July 1968

The invention has a process for the continuous production of halogenated aliphatic Vinyl esters of the general formula

C = C-O-C-R "

i I

ι I

R R '

in which R and R 'denote hydrogen atoms or lower alkyl radicals and R "denotes a halogen-substituted one or mixed halogen-substituted lower alkyl radical represents, by reacting dry acetylene and an aliphatic halogen monocarboxylic acid in the presence of a catalyst and a polymerization inhibitor.

It is known to produce halogenated aliphatic vinyl esters by single batch processes which a halogenated monocarboxylic acid in the liquid phase in the presence of a mercury salt catalyst is reacted with acetylene. Furthermore, the conversion of ecetylene gas with vapors of trifluoroacetic acid known, which is heated to about 170 ° C and passed over a heated catalyst be made from a zinc or cadmium compound, e.g. B. a salt of these metals with a saturated Fatty acid.

From British patent specification 589197, for. B. a discontinuous method of production the vinyl esters of fluorinated carboxylic acids known in which a mixture of trifluoroacetic acid in the presence a catalyst consisting of a mixture of mercury oxide with a mercury salt as well as a small amount of hydroquinone is converted at elevated temperatures, many hours of reaction time and overnight standing are required.

The above procedures are one-shot that are time consuming and very little perform well, yielding about 30 to 80% esters. The life of the catalysts is low, a large number of by-products are formed which are removed from the mixture must in order to obtain an essentially pure ester and little unreacted Acid recovered. The disadvantages mentioned above, as well as the need to use require a carefully worked out system to separate the ester from the by-products, that these procedures are time consuming and expensive.

Process for the continuous production of
halogenated aliphatic vinyl esters

Applicant:

Monsanto Company, St. Louis, Mo. (V. St. A.)

Representative:

Dr. E. Wiegand and Dipl.-Ing. W. Niemann,

Patent attorneys,

8000 Munich 15, Nussbaumstr. 10

Named as inventor:
Tommy LyIe Tolbert, Chapel Hill, N. C;
William Arthur Waddell Jr.,
Falkville, Ala. (V. St. A.)

Claimed priority:

V. St. v. America January 16, 1961 (82 709)

It should also be noted that the known methods require high temperatures, which in turn requires additional equipment.
A process for the preparation of vinyl esters from acetylene and fatty acids in the presence of zinc or cadmium salts of organic acids is known from German patent specification 588 352, in which the acetylene is allowed to act on the fatty acids which are in the liquid phase and which have at least 5 carbon atoms. It also helps to temperatures between 120 and 300 ° C, preferably 160 to 19O ⁰ C, at superatmospheric pressure, eg. B. 20 to 25 atmospheres applied. The process can be carried out batchwise or continuously.

The known process requires special equipment and leads to products which contain considerable amounts of by-products.
It is also known from German Patent 483 780 a process for the preparation of esters of vinyl alcohols in which acetylene is allowed to act in the presence of catalysts on bodies with carboxyl groups in order to inhibit the transition of the resulting vinyl compounds into ethylidene bodies while reducing the concentration of the vinyl esters formed . This procedure does not apply to the manufac-

809 568/554

processing of halogenated products; the resulting The amounts of polymerization inhibitor,

Vinyl compounds are said to be permanent with the help of a thinner and catalyst, which in the suitable solvent. Reaction can be applied to help one The German patent gives no indication of high yields of ester obtained, fluctuate over a technically advantageous production of the broad areas. The amounts of inert diluent coming halogenated aliphatic agents which can be applied Vinyl ester. are only due to practical handling limits

The object of the invention is the continuous heart, the desired reaction rate and position of halogenated aliphatic vinyl esters limits the plant. Only catalytic menach a mode of operation which, in particular, requires less catalyst to achieve the reaction is expensive and runs faster than required; however, if desired, the Known working methods and the ratio of the weight of the catalyst to the weight of the products fall, which are only a low content of minor the initial acid charge high. the products. Acetylene gas flow rate or

The inventive method for the continuous 15 of the mixture of acetylene with an inert gas Manufacture of halogenated aliphatic carriers is important, they should be at least as large Vinyl esters is characterized by being able to remove the ester from the reaction zone, just as he did a mixture of dry acetylene and one is formed to remove. It must be such that Inert gas by a liquid mixture from a spray of the liquid in the reaction zone anhydrous aliphatic halogen monocarbon 20 the sides of the vessel is avoided and in the acid, a catalyst, a polymerization cooler and the vapors of the newly formed ester inhibitor and an inert diluent that removes the entrained acid in an appropriate manner to a temperature between the boiling point of the be removed from the gaseous mixture produced ester and the boiling point of the origin can.

borrowed acid is heated, passes through the ester after 25 The only limitation with regard to the cooling requirement its formation removed and that from the means consists in the fact that the cooling temperature is decreasing Gas stream recovered acid and ■ half the boiling point of the ester produced and the recovered acetylene in the reaction above the condensation point of the acetylene zone back. must lie. The method according to the invention

According to a preferred embodiment of FIG. 30, the invention is generally carried out under atmospheric pressure is the system managed before the introduction of the; however, it can either be under increased dry acetylene and an inert gas carrier take place under or under reduced pressure, holding gas stream by passing as long as the boiling point of the ester produced purged with dry nitrogen gas. lower than that of the associated or original

The process according to the invention is based on the initial acidity.

part that at comparatively low temperatures In the examples, unless otherwise stated

tures worked and a high yield is given, all parts and percentages at least 85 to 98% can be achieved. on a weight basis.

In the method according to the invention, _. -I ₁

be worked so that the dry acetylene 40 example!

containing gas stream into a heated mixture of In a three-necked round-bottomed flask of 11 capacity

the aliphatic halogen monocarboxylic acid, the fortune, which with a gas inlet pipe, a Catalyst as well as the polymerization inhibitor and vessel thermometer, a magnetic stirrer the gas stream flowing out of the reaction zone and a Vigreux column of about 30 cm a condenser and a series of cold traps 45 was seen, a mixture of 669 g of water was passed is, the halogenated ester formed free liquid trifluoroacetic acid, 2 g hydroquinone, and the unused acid vapors condensed 3.5 g of mercury oxide and 3.5 g of mercury sulfate are introduced, the condensate of a fractionated distile. In this mixture, which is stirred lation or other conventional separation and kept at 40 to 48 ° C, 400 method, such as a chromatographic fraction 5 ° to 450 ecm per minute of dry acetylene gas nation, is subjected to the ester initiated by the. The level or height in the react acid is separated and the recovered vessel was made by gradually adding Acetylene and the separated acid in the reac- further acid kept essentially constant, tion zone are returned. The vinyl trifluoroacetate, which is produced by this reaction Acid fumes and the ester fumes generated from the 55 tion was removed from the reaction zone The reaction center in the stream containing acetylene is flushed out by the unreacted acetylene. Gas removed, with essentially all of the major portion of entrained acid Impurities and by-products in the reac- in the Vigreux column are removed from the gas stream tion zone are left, so that an advantageous and returned to the reaction zone. Of the Recycle of essentially pure acid and 60 major part of the ester vapors and the remainder of the Essentially pure acetylene and its re-entrained acid were removed from the gas stream can be used in the process. by condensation in a water cooled The removal of ester and acid leaves the cooler and a trap removed. Of the essentially pure acetylene, which was in a drive can be used again. The Acid 65 series of cold traps which is set at dry ice temperature after the separation from the ester were maintained temperature again, collected. The acetylene used without a shutdown or under-gas, with the entrained acid and the ester breakage the same is required. steam removed, was then in the supply

stood to be put back into circulation. The ester and the acid were distilled separated, the acid being put back into circulation in the reaction zone. During the encore of a total of 1353 g more acid, 972 g of acid were recovered for recirculation, i.e. together with 1153g vinyl trifluoroacetate; this represented a conversion of 46.5% and a yield of 89.5%. The pot residue was less than 5% of the total of trifluoroacetic acid, which was consumed in the overall reaction.

Example 2

A mixture of 309 g of trifluoroacetic acid, Introduced 2 g hydroquinone, 5 g mercury oxide and 5 g mercury sulfate. The reaction system was flushed with dry nitrogen to purge it of air and moisture. Dry Acetylene gas was added to the reaction mixture, which was kept at 43 to 47 ° C, with such Blown in speed so that there was essentially no splash. Within a few minutes changed in the reaction mixture the color from pale orange to black, and the temperature of the Mixture rose by 4.5 ° C, indicating that a reaction was taking place. Soon the reaction mixture became saturated with ester, and liquid began to appear in the traps to kick. When the liquid level in the reaction mixture had dropped properly, was started with the gradual addition of acid to maintain a constant level in the reaction vessel was sustained; the addition was continued until a total of 892 g of acid was in the original mixture had been added. After a total reaction time of about 20 hours the reaction was interrupted. As in Example 1, the reaction vapors were in one with a water-cooled condenser and a collecting device and condensed in a series of cold traps. Distillation of the condensate gave 622 g of recovered acid with a boiling point of 72.5 ° C and 649 g of the vinyl trifluoroacetate having a boiling point of 40 to 41 ° C; this represented a transformation of 44.2% and a yield of 91.3%.

Example 3

In a device of the type used in Example 1, which was flushed with nitrogen gas was, a mixture of 720 g of trifluoroacetic acid, 3 g of hydroquinone, 7 g of mercury and Introduced 7 g of mercury sulfate. It was dry acetylene in the reaction mixture, which at 39 to 49 ° C was blown at such a rate that essentially no Injecting took place. Within a few minutes, the color of the reaction mixture changed from pale orange to black, and so did the temperature of the mixture rose about 5 ° C; in this way it was shown that a reaction was taking place. As soon as condensate was collected, more acid was gradually added to a constant level in the Maintain reaction vessel; the addition was continued until a total of 1821 g Acid had been added to the original mixture. After a total reaction time of the reaction was interrupted for about 28 hours. The reaction vapors were the same condensed as in Example 1. Distillation of the condensate gave 1191.5 g of recovered acid with a boiling point of 72.5 ° C and 1442 g of vinyl trifluoroacetate with a boiling point of 40 up to 41 ° C; this meant a conversion of 46.2% and a yield of 87.3%. The vascular residue was less than 5% of the total amount of trifluoroacetic acid used in the overall reaction had been consumed.

Example 4

A mixture of 366 g of chlorodifluoroacetic acid was placed in a reaction vessel of the type used in Example 1 (a technical product which - as shown by gas chromatography - had a purity of only 70%), 1 g of hydroquinone, 3 g of mercury oxide and 3 g of mercury sulfate brought in. The reaction system was purged with dry nitrogen to remove air and moisture to cleanse. It was dry acetylene gas in the reaction mixture, which at 85 was maintained at 95 ° C at a rate that avoided splashing. Within a few minutes, the color of the reaction mixture changed from orange Black, and the temperature of the mixture rose several degrees, indicating a reaction took place. The addition was continued until a total of 236 g of acid was added to the original Mixture had been added. At the end of a 13 hour run with a subsequent For short-term shutdowns, an additional 2 g of mercury oxide and 2 g of mercury sulfate were added. After a total reaction time of about 18 hours, the reaction was interrupted. the Reaction vapors were condensed in the same manner as in Example 1. The distillation of the Condensate gave 161.7 g of recovered pure acid with a boiling point of 122 ° C and 307.3 g of vinyl chloride fluoroacetate with a boiling point of 75 to 76 ° C; this represented a conversion of 59.9% and a yield of 97.5%.

Example 5

A mixture of 770.5 g of chlorodifluoroacetic acid was placed in a reaction vessel of the type used in Example 1 (a technical product which - as shown by gas chromatography - had a purity of only 70%), 1 g of hydroquinone, 3 g of mercury oxide and 3 g of mercury sulfate brought in. The system was purged with dry nitrogen to remove air and moisture to clean. It was dry acetylene gas in the reaction mixture, which at 74 to 80 ° C was held at a rate that avoided splashing. It the usual color change and temperature rise were observed. After about 10 hours Another 3 g of mercury oxide and 3 g of mercury sulfate were added. After a total reaction time of about 23 hours the reaction was interrupted. The reaction vapors were in the same Condensed manner as in Example 1.

Distillation of the condensate gave 134 g of pure acid recovered with a boiling point of 122 ° C and 480.1 g vinyl chlorodifluoroacetate with a boiling point

point from 75 to 76 ° C; this represented a conversion of 75% and a yield of 98.3%.

Claims (2)

Patent claims: 1. Process for the continuous production of halogenated aliphatic vinyl esters of general formula HO C = C-O-C-R " R R ' in which R and R 'denote hydrogen atoms or lower alkyl radicals and R "denotes a halogen-substituted one or is a mixed halogen-substituted lower alkyl radical, by reaction of dry acetylene and an aliphatic halogen monocarboxylic acid in the presence of one Catalyst and a polymerization inhibitor, characterized in that one Mixture of dry acetylene and an inert gas through a liquid mixture of a anhydrous aliphatic halogen monocarboxylic acid, a catalyst, a polymerization inhibitor and an inert diluent, that at a temperature between the boiling point of the ester produced and the boiling point the original acid is heated, passes through, the ester is removed as it is formed and the acid and recovered from the effluent gas stream Recirculates acetylene into the reaction zone. 2. The method according to claim 1, characterized in that the system before the introduction the dry acetylene and an inert gas carrier-containing gas stream by passing it through purged by dry nitrogen gas. Considered publications:
German Patent Nos. 483 780, 588 352;
British Patent No. 589 197;
U.S. Patent No. 1790,920. 809 568/554 6.68 © Bundesdruckerei Berlin