RU2078759C1 - Method for production of chlorides of carboxylic acids - Google Patents

Abstract

FIELD: production of halogenated lower carboxylic acids. SUBSTANCE: chlorides of carboxylic acids are prepared by interaction of lower aliphatic acid with inorganic oxohalogenide, dimethylformamide being used as catalyst. Oxochloride of phosphorous is used as mentioned above inorganic oxohalogenide. The process is carried out by boiling of reaction mixture, molar ratio of aliphatic acid, phosphorous oxochloride and dimethylformamide being 1: 0.67: (0.25-0.33) respectively. EFFECT: improved efficiency of the method. 1 cl, 3 tbl

Description

Данные соединения широко используются в качестве промежуточных продуктов в органическом синтезе.The invention relates to the field of chemistry of organic compounds, specifically to methods for producing carboxylic acid chlorides of the following structure:

These compounds are widely used as intermediates in organic synthesis.

The following methods for the synthesis of carboxylic acid chlorides are known:
1. The interaction of carboxylic acids with phosphorus pentachloride.

RCOOH + PCl ₅ __ → RCOCl + POCl ₃ + HCl
2. The interaction of carboxylic acids with phosphorus trichloride.

3RCOOH + 2PCl ₃ __ → 3RCOCl + P ₂ O ₃ + 3HCl
3. The interaction of salts and esters of carboxylic acids with phosphorus oxychloride.

2RCOOR ′ (Na) + POCl ₃ __ → 2RCOCl + NaPO ₃ + NaCl
4. The interaction of carboxylic acids with thionyl chloride.

 Moreover, the highest yields of up to 89% of acid chlorides were achieved by carrying out the reaction in the presence of catalytic amounts of dimethylformamide. It is this method using a dimethylformamide catalyst that is selected as a prototype.

Недостатком данного метода является повышенные требования к качеству хлористого тионила. Для получения чистого хлорангидрида карбоновой кислоты исходный хлористый тионил рекомендуют дополнительно очищать. Острый дефицит хлористого тионила затрудняет применение этого метода для получения укрупненных количеств хлорангидридов карбоновых кислот.

The disadvantage of this method is the increased quality requirements of thionyl chloride. To obtain pure carboxylic acid chloride, the starting thionyl chloride is recommended to be further purified. An acute deficit of thionyl chloride makes it difficult to use this method to obtain aggregated amounts of carboxylic acid chlorides.

 The above disadvantages does not have the proposed method for producing carboxylic acid chlorides by the interaction of phosphorus oxychloride with carboxylic acids in the presence of a dimethylformamide catalyst.

Процесс осуществляется в емкостном реакторе с обогревом, перемешивающим устройством, обратным холодильником и термометром. Процесс проводят при T 80 100^oC и молярном соотношении реагентов: карбоновая к-та: POCl₃: ДМФ 1: примерно 0,67 0,25 0,33. По предложенному методу хлорангидриды карбоновых кислот получают с выходами до 93%
Чистота и строение полученных соединений подтверждены данными элементного анализа, ИК-спектроскопии, ГЖХ, а также соответствием найденных физических констант литературным данным.

The process is carried out in a capacitive reactor with heating, mixing device, reflux condenser and thermometer. The process is carried out at T 80 100 ^o C and a molar ratio of reagents: carbonic to-that: POCl ₃ : DMF 1: about 0.67 0.25 0.33. According to the proposed method, carboxylic acid chlorides are obtained in yields of up to 93%
The purity and structure of the obtained compounds are confirmed by elemental analysis, IR spectroscopy, GLC, as well as the correspondence of the found physical constants to literature data.

 The high yield of carboxylic acid halides, their purity, the use of available starting compounds produced by our industry and the ease of processing process determine the highest processability of the proposed method compared to the known ones.

 Phosphoric anhydride formed as a by-product after treatment with aqueous ammonia can be proposed as fertilizer.

 Example No. 1. Obtaining acetic acid chloride.

In a reactor equipped with a stirrer, dropping funnel, reflux condenser and thermometer, 38.2 (0.249 M) phosphorus oxychloride is placed. 22.3 g (0.371 M) of acetic acid and 7 ml (0.019 M) of dimethylformamide are charged into a dropping funnel. The reaction mass is heated to 80 ^° C. and a mixture of a dropping funnel is added to it over a period of 15 -20 minutes. Then, the reflux condenser was replaced with a direct one and the resulting acetic acid chloride was taken at a temperature in pairs of 50–60 ^° C. Upon repeated distillation, a fraction was collected in the temperature range of 51–53 ^° C. 25.0 g of chloroacetyl chloride was obtained (86% yield), n $\genfrac{}{}{0ex}{}{\text{twenty}}{\text{D}}$ = 1.3893 which corresponds to the literature: T. bale. 51 - 52 ^o C, n $\genfrac{}{}{0ex}{}{\text{twenty}}{\text{D}}$ = 1.38976.

By elemental analysis it was found: hydrolyzable chlorine 45.5, for C ₂ H ₃ ClO calculated: Cl 45.2.

IR spectrum: 18.19; 1428; 1370; 1102; 1053; 955 (cm ^-1 ) did not detect noticeable amounts of impurities.

 The results of the study of the effect of the amount of dimethylformamide on the yield of the target acetyl chloride are shown in Table 1.

 As follows from the table, the maximum yield of acetyl chloride was achieved with a molar ratio of reagents: acetic acid phosphorus oxychloride dimethylformamide 1 0.67 0.25. A further increase in the content of dimethylformamide does not increase the yield.

 Example N2. Obtaining propionic acid chloride.

40.4 g (0.263 M) of phosphorus oxychloride are charged into a reactor equipped with a stirrer, a thermometer, a reflux condenser and a dropping funnel. 29.1 g (0.393 M) of propionic acid and 10 ml (0.130 M) of dimethylformamide are charged into a dropping funnel. The reaction mass is heated to 100 ^o C. Next, the process is carried out according to the above method. The obtained propionic acid chloride is distilled at atmospheric pressure in the temperature range of 77 - 80 ^o C. Received 34.1 g of propionic acid chloride (yield 93%) n $\genfrac{}{}{0ex}{}{\text{twenty}}{\text{D}}$ 1.4050 which corresponds to published data: T. bale. 80 ^o C, n $\genfrac{}{}{0ex}{}{\text{twenty}}{\text{D}}$ = 1.40507.

Elemental analysis found: Cl 38.1 for C ₃ H ₅ ClO calculated: Cl 38.4.

IR spectrum: 19.22; 1785; 1460; 1409; 1390; 1265; 1252; 1115; 1085; 10.12; 915; 780; 650 cm ^{-1 -} did not detect noticeable amounts of impurities.

 The results of the study of the effect of the amount of dimethylformamide on the yield of the target propionyl chloride are given in table 2.

 As follows from the table, the maximum yield of propionyl chloride was achieved with a molar ratio of reagents: propionic acid phosphorus oxychloride - dimethylformamide 1 0.67 0.33. A further increase in the content of dimethylformamide does not increase the yield.

 Example N3. Obtaining trichloroacetic acid chloride.

77.8 g (0.507 M) of phosphorus oxychloride are charged to the reactor. 123.6 (0.756 M) trichloroacetic acid and 19.2 ml (0.249 M) dimethylformamide are added to the dropping funnel. The reaction mass is heated to 100 ^o C and the contents of the dropping funnel are added to it over 20 minutes. In this case, the stirred reaction mass is in a soft boiling state. Then the temperature was brought to room temperature and the reaction mixture was extracted with chloroform. Chloroform was evaporated and the residue was distilled at atmospheric pressure.

Receive 126.5 (yield 92%) of trichloroacetic acid chloride with a boiling point of 114 118 ^o C, n $\genfrac{}{}{0ex}{}{\text{twenty}}{\text{D}}$ = 1.4700 which corresponds to the literature: T. bale. 118 ^o C. Elemental analysis found: Cl 77.7; for C ₂ Cl ₄ O, Cl 78.1 was calculated. No proton was detected in the PMR spectrum. IR spectrum: 1797, 1735, 1017, 839, 800, 732 cm ^-1 did not detect noticeable amounts of impurities.

 The results of the study of the effect of the amount of dimethylformamide on the yield of the target acid chloride are given in table 3.

 As follows from the table, the maximum yield of trichloroacetic acid chloride was achieved with a molar ratio of reactants: trichloroacetic acid phosphorus oxychloride: dimethylformamide 1 0.67 0.33. A further increase in the content of dimethylformamide does not increase the yield.

 In all cases (examples 1 to 3), the soft boiling regime during which the reaction is carried out is optimal, because a decrease in temperature leads to a decrease in the reaction rate.

 The proposed method for producing carboxylic acid chlorides has the following advantages relative to known methods.

1. The use of this method allows to obtain the target product with a yield of up to 93%
2. The target product does not contain undesirable impurities and does not require additional purification.

 3. This method involves the use of feedstock products of large-scale production in contrast to the prototype.

 4. The technological design of the process involves the use of standard equipment.

Claims (1)

 A method of producing carboxylic acid chlorides by reacting a lower aliphatic acid with an inorganic oxo-halide during catalysis with dimethylformamide, characterized in that phosphorus oxychloride is used as the oxyhalide and the process is carried out under the conditions of the reaction mixture boiling at a molar ratio of phosphorus oxychloride dimethylformamide 1 0.67 (0.25 0 , 33).

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