SU169529A1 - Method of producing 3-trifluoromethyldiphenylamine - Google Patents

Description

A known method for the preparation of 3-trifluoromethyldiphenylamine is that 3-trifluoromethylaniline is acetylated, 3-trifluoromethyl-acetanilide is isolated and crystallized. After that, the latter is condensed with bromobenzene and N-acetyl-3-trifluoromethyldiphenylamine is isolated by distillation under high vacuum, then it is hydrolyzed in an hydroalcoholic medium in the presence of hydrochloric acid.

In order to simplify the process of increasing the product yield, it has been proposed to acetylate 3-trifluoromethylaniline with acetic anhydride, after which the reaction product is directly condensed with bromobenzene and hydrolyzed in an aqueous-alcoholic medium in the presence of alkali. Get 3-trifluoromethyldiphenylamine with the release of SQo / o.

A portion of the starting 3-trifluoromethylaniline is regenerated using it in the re-synthesis.

Example 1. Synthesis of 3-trifluoromethyldiphenylamine. In a 1 L three-necked flask equipped with a dropping funnel, a mechanical stirrer with reflux condenser and a reflux condenser, to a stirred 3-trifluoromethylaniline 161.11 g (1.02 g-mol) add 132.6 g (1.3 g g mole of acetic anhydride. The reaction mixture is boiled for 2 hours, after which, replacing the addition funnel with a capillary, and a reflux condenser with a desiccant, tap and receiver, in a small vacuum (150 mm Hg) distillation acetic acid and excess acetic anhydride are formed.

550 g (3.5 g-mol} of dry bromobenzene, 6.91 g of anhydrous potash, 5 g of copper bromide, 2.5 g of copper powder and 0.5 g of potassium iodide are added to the molten residue with vigorous movement. 40 cm long reflux condenser with descending condenser and receiver. The reaction mass is heated in an oil bath with stirring for 36 hours at a rate such that about 200 g of bromobenzene and water are distilled off (the temperature of the reaction mixture rises from 145 ° C to the beginning of the reaction to

182-185 ° C. B end). The residue of bromobenzene is distilled off from the reaction mixture with hot steam until the oily drops disappear in the distillate and white crystals appear (3-trffluoromethyl-acetanilide, which has not entered into the reaction).

The residue in the flask is stratified, the aqueous layer is separated, and 500 ml of ethyl alcohol is added to the organic. The resulting solution is filtered on a porous glass plate. The solution is added to the filtrate.

dy and with stirring, the reaction mass is refluxed in an air bath for 9 hours. After cooling to room temperature, 700 ml of water was added to the reaction mass, the separated oil was separated, and the aqueous layer was extracted with 250 ml of dichloroethane. The dichloroethane extract and oily layer were combined, and the solution was dried over anhydrous magnesium sulphate. Dichloroethane is distilled off, and the residue is distilled in vacuo. The following fraction is obtained:

I.3-trifluoromethylaniline; t. cues. 73-75 ° C (4 mm Hg. Art., Yield 48.3 g (30 Vo from the unloaded);

II.2-trifluoromethyldiphenylamine; t. cues. 125-127 ° C (3 ML1 Hg. Art.), Yield 62 p / o (from the theoretical value, calculated as 3-trifluoromethylaniline).

Example 2. C and St e 3-t p and f t o rmet and l d and f n n c l a m i n a from regenerated 3 - t p and f t o r m e t and l a n and l and na From 48.3 g of 3-trifluoromethylaniline, isolated in Example 1 and not subjected to any additional treatment, the following is obtained:

I. 3-trifluoromethylaniline 14.5 g t. Kip. 73-75 ° C (4 mm Hg. Art.);

P. 2 - trifluoromethyldiphenylamine 40 g; t. cues. 125-127 ° С (3 mm of mercury):

Thus, the total yield of 2-trifluoromethyldiphenylamine is SQo / o, calculated on the 3-trifluoromethylaniline introduced into the reaction in the first irimer.

Subject invention

The method of producing 3-trifluoromethyldiphenylamine using acetylation of 3-trifluoromethylaniline, condensing the latter with bromobenzene, followed by hydrolysis of the resulting product in an aqueous-alcoholic medium, characterized in

the product, the acetylation product is directly condensed with bromobenzene and the hydrolysis of the substance obtained is carried out in the presence of alkali.