RU1770318C - Method of 3-dialkylamino-2-butenales synthesis - Google Patents

Abstract

Method for the preparation of 3-dialkylamino-2-butenals. Usage: as intermediates for the production of five, six, and six-membered heterocycles, as well as macro cycles. SUMMARY OF THE INVENTION: Product: 3-di (ethyl) amino-2-butenal (C2H5) 2 CH-CHO. BF CeHisNO, move 27%, b.p. 147-148 ° C (7 mmHg). ..- di (propyl) amino-2-butenal CH3-C M (C3H7) 2 CH-CHO. BF Xu HigNO, yield 25%, b.p., 144-145 ° C (4 mmHg), 3-di (butyl) - (amino) -2-butenal, CH $ - (C4H9) 2 CH-CHO, BF Ci2H23NO. yield 43%, bp 149 ° C (3 mmHg). Reagent; . Reagent 2: R2NH. where R-C2H t SzN, C4Nd. Reaction conditions: in an aqueous-alcoholic medium in the presence of 3-5% gy / potassium oxide based on the weight of the solvent pr 50-70 ° C.

Description

The invention relates to the field of organic chemistry, namely to the synthesis of 3-dialkylamino-2-butenals of the formula (I)

R, -C5C-ct ° + R 2R 3Ш- R, -C CH-Ct NR2R3

% s-C;

N (RV

 N

la-in 2

where (a), СЗНу (b), С4Нд (c).

Representatives of this class of substances serve as valuable starting compounds for the preparation of practically important five-, six-, seven-membered heterocycles, as well as macrocycles.

A known method of producing 3-dialkylamino-2-butenals by the interaction of amines with acetylene aldehydes (Veg, 1952, Bd 85, S 841-851; Izv. AN USSR, ser.chem. 1985, No. 11, S. 2640-2642) . The reaction proceeds with a high yield of 3-dialkylamino-2-butene.

However, this method can only be used in laboratory practice because of the low availability and stability of the starting acetylene aldehydes.

A prototype of the present invention is a method for producing 3-dialkyl / and mino-2-butenals by reacting diacetylene with a water-alcohol solution of diethylamine (ZhOKh, 1973, v. 9, v. 8, 1599-1601).

HC C-C5CHt (CiH5) iVlH-l-H10-

W 00

about

lCH-C-CH5 + CH3-C CH-C H

iiwtCaHsli

g, - ..

The disadvantage of this method is the low yield of 3-diethylamino-2-butenalc, not exceeding 10%.

An object of the invention is to increase the yield of 3-dialkylsmino-2-butenal.

The goal is achieved in that in the method for producing 3-dialkylamino-2-butenals by the reaction of diacetylene with an aqueous-alcoholic solution of amine, the process is carried out in the presence of KOH, in the amount of 3-5% by weight of the solvent, at 50-70 ° C. The yield reaches 40%.

The introduction of 3-5% KOH into the reaction mixture promotes the primary hydration of dicetilene, followed by the conversion of the hydration product to the target product when reacted with an amine.

The reaction is carried out at 50-70 ° C, since practically no reaction of diacetylene with amines occurs when the temperature drops below 50 ° C; an increase in temperature above 70 ° C results in a decrease in the yield of the target product due to an increase in the rate of addition of amine to diacetylene in a competing direction, namely, with the formation of 4-dialkylamino-3-buten-2-ones (II).

When using KOH in an amount of less than 3%, the reaction does not proceed practically, an increase in the KOH content of more than 5% does not affect the yield of the desired 3-dialkylamino-2-butenal.

Alcohol is added to the reaction mass to increase the solubility of diacetylene. The heating time is 1 hour; the time is determined by the optimal yield of the target product. After completion of the reaction, the expected product is isolated by fractional distillation in vacuo.

The structure of the obtained 3-dialkylamino-2-butenals has been proved by IR and PMR spectroscopy. Thus, in the IR spectrum of compounds (I) there are bands corresponding to stretching vibrations of the carbon-carbon double bond (1610) and the carbon-oxygen double bond (1680 cm). In the 1H-NMR spectrum of 3-dialkylamino-2-butenals, the singlet of the proton of the aldehyde group (Nd) is located in the region of 9.36–9.47 ppm, and the signal of the vinyl proton (HB) is represented by a doublet in the region of 4.3–4.8 ppm. ns on NA sn3-s en-s o

NRZ H

The spin-spin coupling constant is 7.4 Hz. Protons of the methyl group resonate at 2.25 ppm. The proton signals of the alkyl substituents at the nitrogen atom are split in the usual way.

The essence of the method is illustrated by the following examples.

Example 1. A solution of 10 ml (0.1 mol) of diethylamine and 5 g of KOH in 80 ml of water and 20 ml of ethanol was heated to 50 ° C and 5 g (0.1

mole) of diacetylene. diluted with argon. After completion of the passage of diacetylene, the reaction mixture was kept at 70 ° C for 1 h. The product was salted out with potash, the oil layer was separated, and the mixture was extracted with benzene. The benzene extracts and oil were combined, dried, the solvent was distilled off in vacuo, the residue was fractionated in vacuo, and a fraction boiling at a temperature of 147 148 ° С (7 mm Hg) was isolated.

20 1.5670, d4 0.9413. The yield of 3-diethylamino-2-butenal was 3.8 g (27%).

Example 2. Under the conditions of example 1 from 5 g of diacetylene and 10 ml of diethylamine and 3 g of KOH in a mixture of 80 g of water and 20 g of ethanol at

50 ° C. obtained 3-diethylamino-2-butenal with a yield of 35%.

Example 3. Under the conditions of Example 1, from 0.1 mol of dipropylamine, 5 g of KOH; 80 g of water, 20 g of ethanol at 70 ° C gave 3-dipropylamino-2-butenal. Yield 4.1 g (25%) T. boiling point. 144-145 ° C (4 mmHg), 20 1.5587, d420 0.9036.

Example 4. Under the conditions of Example I and 0.08 mol of dibutylamine, 0.06 mol of diacetylene in a mixture of 80 g of water and 20 g of ethyl alcohol at 70 ° C, 3-dibutylamino-2-butenal was obtained in 1.5 g yield (43 %) T.kip. 149 ° C (3 mmHg).

Thus, the proposed method

allows to increase the yield of the target product in 1.5-2 times in comparison with the prototype. The starting diacetylene is commercially available as it is obtained as a by-product in the production of acetylene v natural hydrocarbon feed in an amount of 5% of the amount of acetylene produced.

Claims (1)

The claims Method for the preparation of 3-dialkylamino-2-butenals of general formula SNZ-S I h N K) 2 where R-C2H5, C3H, CiHg, the interaction of diacetylene with a secondary amine in an aqueous-alcoholic medium upon heating, characterized in that that, in order to increase the yield of the target products, the process is carried out in the presence of potassium hydroxide, in an amount of 3-5% by weight of the solvent, at 50-70 ° C.