CS242218B1 - A process for preparing .beta.-bromoalkane or .beta.-bromoalkanedioic acids - Google Patents

Abstract

The invention relates to a method for preparing α-bromoalkanoic or α-bromoalkanedioic acids by reacting alkanoic or alkanedioic acids with bromine, in the presence of an oxidizing agent, which is chlorine or sulfuryl chloride, at a molar ratio of bromine to oxidizing agent of 1: 0.9 to 1.

Description

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BACKGROUND OF THE INVENTION The present invention relates to a process for the preparation of .beta.-bromoalkane or .alpha.-bromoalkanedioic acids by reaction of alkanes or alkanediic acids with bromine in the presence of an oxidizing agent such as chlorine or sulfuryl chloride. The compounds can be used as intermediates in the preparation of herbicides and growth regulators. The literature describes the preparation of α-bromo-alkanoic acids by the procedure of Hella-Volhard-Zelinsky, which consists in the reaction of alkanoic acids with bromine in the presence of phosphorus halides [Volhard J .: Ann. CFJ: Chem. Soc.121, 1161 (1922), Marvel C. S., Org. Synthe-ses 20, 106 (1940), Marvel C .: Org. Syn-theses 21, 74 (1941), Orton J. K. P., J Chem.Soc. 123, 3081 (1923), Gal H .: Ann. 129 53 (1864)].

Sulfur used as the catalyst for the bromination of acetic acid [Genvresse P .: Bull. Soc.Chim. France (3) 7, 364 (1892)] or acce-tanhydride and pyridine (Natelson S .: Org. Syntheses, Col. vol. III, 381).

The lower alkanedioic acids are brominated in the 1-position even at low temperature alone with bromine in the absence of catalysts [Willstatter R .: Ber. 35, 1375 (1902), Palmer. S .: Org. Syntheses Col. vol. I., 240 (1932)].

A disadvantage of the hitherto known methods for the preparation of α-bromoalkane or α-bromoalkanedioic acids by the reaction of alkane or alkanedioic acids with bromine has been the low yield of the reaction because it forms hydrogen bromide from half of the bromine.

It has now been found that the process for the preparation of α-bromoalkanoic or α-bromoalkanedioic acids by the action of the alkane or alkanedioic acid with the bromine according to the invention is undesirable.

The present invention is based on the fact that the reaction is carried out in the presence of an oxidizing agent, which is chlorine or sulfuryl chloride in a mutual bromine-oxidant molar ratio of 1: 0.9 to 1. a mixture of hydrogen chloride and sulfur dioxide. Gas chromatography showed that chloro-substituted derivatives were not formed by acid reaction. The advantage of this method of preparation, the fact that in the presence of an oxidizing agent, hydrogen bromide is formed again into bromine, which in turn reacts with the alkane or alkane, respectively. alkanedic acid. In contrast to previously known methods, half the amount of bromine can be used in the reaction.

The following examples illustrate but do not limit the invention. Example 1

A mixture of 400 ml acetic acid, 80 ml acetic anhydride, 0.6 ml pyridine and 1 ml bromine was heated to 100 PCs. After bleaching the bromine sapod, the reaction mixture was dosed with a 393.4 g bromine / 332 gsulfuryl chloride mixture at a rate such that the bromine feed was sufficient to react. To return the reaction medium to a portion of the hydrogen bromide entrained with the escaping gases (hydrogen chloride and sulfur dioxide), a mixture of 260 mL of acetic acid and 50 mL of acetic anhydride was added dropwise to the reaction mixture. After the completion of the reaction of the reaction components (3 h), the reaction mixture was cooled and, after addition of 30 ml of water, was subjected to distillation.

Distillation gave 192.2 g of bromoacetic acid in 78.8% yield with m.p. 118 degrees Celsius / 4.4 kPa. Example 2

According to the procedure of Example 1, acetic acid was brominated except that equimolar amounts of bromine and chlorine were metered in below the base of the reaction mixture instead of the equimolar mixture of fluorine and sulfuryl chloride. The reaction mixture was stirred vigorously while maintaining the temperature at 95 ° C. After completion of the dosing, small amounts of water were added to the set reaction mixture.

By distillation, bromoacetic acid was isolated in 61.1% yield (used in bromine). Example 3

Following the procedure described in Example 1, α-bromopropionic acid was prepared by reacting propionic acid with bromine and sulfuryl chloride. To 150 g of propionic acid heated to 120 ° C was added a small amount of bromine until its decolorization. After cooling to 100 ° C, 124.2 g of bromine and 104.9 g of sulfuryl chloride were introduced under the reaction mixture. Gases from the reaction medium containing a small amount of bromine and hydrogen bromide were scrubbed with 130 g of propionic acid. After dosing was complete, the reaction mixture was heated for 20 minutes and subjected to rectification. After distillation of the excess propionic acid at 118-120 ° C (5,7 kPa), α-bromopropionic acid was distilled.

Distillation gave 168 g of α-bromopropionic acid in a 70.6% purity yield of 99.0%. Example 4

A mixture of 35.1 g malonic acid and 100 billion methylamine was cooled to 5 ° C. A mixture of 27 bromine and 23 g of sulphuryl chloride was metered in under cooling with Tefoteplote.

After concentration and free crystallization, 52.2 g of monobromononic acid was obtained with m.p. 112 ° C.

Claims (1)

242218 PRSDMET A process for the preparation of α-bromoalkane or α-bromoalkane dioic acids by reacting alkane or alkanedioic acids with bromo-amine, characterized in that the reaction proceeds in the presence of an oxidizing agent which is chlorine or sulfuryl chloride in a mutual bromine / oxi molar ratio. 1: 0.9 to 1.