RU2238261C1 - Tert-butylacetylene production process - Google Patents

Abstract

FIELD: industrial organic synthesis.

SUBSTANCE: tert-butylacetylene is obtained via reaction of tert-butyl alcohol with acetylene in presence of acid catalyst, content of water in liquid reaction mixture ranging from 10 to 50%. Catalyst is selected from sulfuric, phosphoric, trifluoroacetic acid, sulfonic acids, sulfonate cations, and the like.

EFFECT: increased selectivity of formation of desired compound and increased yield thereof at substantially reduced cost.

4 cl, 3 ex

Description

The invention relates to the chemistry of acetylenes, and in particular to a method for producing tert-butylacetylene, and can be used in preparative organic chemistry for the synthesis of propargyl alcohols, ketones, as well as certain medications (for example, terbinafine).

A known method of producing tert-butylacetylene by dehydrobromination of 1,2-dibromo-3,3-dimethylbutane with a suspension of potassium tert-butylate in dimethyl sulfoxide (WLCollier and RS Macomber. Tret-Butylacetylene Revisited. An Improved Synthesis. Methil Migration during Bromination. - J. Org. Chem., 1973, vol. 38, No. 7, p. 1367-1369). The yield of the target compound is more than 91%, but the practical use of this method is difficult due to the high cost of dimethyl sulfoxide and potassium tert-butylate.

There are also known methods for producing tert-butylacetylene by dehydrochlorination of 2,2-dichloro-3,3-dimethylbutane in the presence of a 4-fold excess of potassium hydroxide, which is wetted with ethanol to lower the melting point. However, in this method, the target compound is isolated in a mixture with ethanol, and therefore, additional purification (washing with water, drying, distillation) is required, which significantly increases the cost of the process (WHPuterbaugh and MSNewman. Synthesis and some Reactions of cis- and trans - Di-t-Butylethylenes. - J. Am. Chem. Soc., 1959, vol. 81, No. 7, p. 1611-1614, PD Bartlett and LJ Rosen. An Acetylenic Analog of Neopentyl Bromide; Evidence that the Hindrance to Displacement Reactions in Neopentyl Halides is Steric in Nature. - J. Am. Chem. Soc., 1942, vol. 64, No. 3, p. 543-546).

Closest to the proposed is a method for producing tert-butylacetylene, which consists in the condensation of tert-butyl alcohol with acetylene.

So, through a mixture of 30 ml (0.34 mol) of 70% sulfuric acid, 30 ml (0.32 mol) of tert-butyl alcohol and 1 g of nickel sulfate, 3 L of acetylene is passed for 2 hours at 25-30 ° C. Then the reaction mass is poured onto 40 g of ice. After several fractional distillations, tert-butylacetylene is obtained with a yield of ~ 2.1% on charged or 42% on reacted tert-butyl alcohol (P.V. Kazakov, E.I. Demina. Alkylation of acetylene with tert-butyl alcohol. - Izv. . AN, Ser. Chem., 2002, No. 11, s. 1978-1979).

The disadvantages of this method include the low yield and low selectivity of the formation of tert-butylacetylene due to the production of a by-product, diisobutylene.

The present invention is aimed at increasing the selectivity of the formation of the target compound, increasing its yield and significantly reduces the cost of the process of obtaining tert-butylacetylene.

The essence of the invention consists in the development of a method for producing tert-butylacetylene by the interaction of tert-butyl alcohol with acetylene in the presence of an acid catalyst and a certain amount of water.

To increase the selectivity of the formation of tert-butylacetylene, the condensation of tert-butyl alcohol with acetylene is carried out in the presence of water, the optimum amount of which is from 10 to 50%.

So, with a water content of 40-50% in the presence of sulfuric acid, the selectivity of tert-butyl acetylene formation reaches 92%. The use of more concentrated solutions leads to an increase in the share of the formation of diisobutylene and a decrease in the yield of the target compound. So, when the content of the reaction mixture is 10% water, the selectivity of the formation of tert-butylacetylene decreases to 55-60%. At high concentrations of water (more than 50%), the reaction rate sharply decreases until it stops.

A similar situation (water concentration) persists when using other acid catalysts, such as phosphoric, trifluoroacetic acid, methanesulfonic acid, p-toluenesulfonic acid, sulfonic acid cation exchangers, etc.

Isolation of the target compound is carried out either by distillation after synthesis, or continuously during the condensation of tert-butyl alcohol with acetylene.

The desired concentration of water in the reaction mixture is achieved either by adding pure water, or using aqueous solutions of acids and (or) tert-butyl alcohol, which expands the raw material base and reduces the cost of obtaining the target compound.

All ingredients used in the synthesis of tert-butylacetylene are commercially available and are cheap, commercially available products.

The essence of the present invention is illustrated, but not limited to the following examples.

Example 1

5 l (0.22 mol) of acetylene is passed through a mixture containing 0.5 mol of sulfuric acid, 0.5 mol of tert-butyl alcohol and 70 ml of water (i.e., the water content of the mixture is 45%), maintaining a temperature of 25-30 ° C. Then the reaction mass is poured onto ice and tert-butylacetylene is isolated by distillation.

Obtain 6.4 g of tert-butylacetylene, so Kip. 37-38 ° C, n $\genfrac{}{}{0ex}{}{\text{20}}{\text{D}}$ 1.3750. ¹ H NMR Spectrum (CCl ₄ , δ, ppm, J, Hz): 1.23 (s, 9H, t-Bu); 1.91 (s, 1H, C = CH). Based on GLC (gas-liquid chromatography) data, the content of the main substance is at least 98%.

According to GLC, the bottom residue contains 30.7 g of tert-butyl alcohol and 0.6 g of diisobutylene.

Thus, the yield of tert-butylacetylene is 92% of the reacted tert-butyl alcohol.

Example 2

Through a mixture containing 0.25 mol of phosphoric acid and 0.25 mol of tert-butyl alcohol and 15 ml of water (i.e., the water content in the mixture is 26%), 8 L (0.36 mol) of acetylene is passed at 40-45 ° C. while distilling off tert-butylacetylene.

Obtain 3.1 g of tert-butylacetylene, in the bottom residue according to GLC contains 15.5 g of tert-butyl alcohol and 0.2 g of diisobutylene.

The yield of tert-butylacetylene is 93% of the reacted tert-butyl alcohol.

Example 3

Acetylene at room temperature was passed through a column that was filled with 80 g of KU-2-8 cation exchanger and irrigated with 92.7 g (1.0 mol) of an 80% solution of tert-butyl alcohol in water. Upon reaching a gas leak, the liquid phase is separated and distilled. Receive

32.9 g of tert-butylacetylene with a basic substance content of at least 98%;

49.5 g of tert-butyl alcohol (in the form of an aqueous azeotrope, the content of the basic substance is 87%), which is used in the following synthesis.

As a result, the yield of tert-butylacetylene is 95.5% of the reacted tert-butyl alcohol.

The spectral parameters and physicochemical constants of tert-butylacetylene obtained in the above examples are identical.

Thus, the proposed method is easily implemented in an industrial environment, provides an expanded assortment of acid catalysts, in particular the use of sulfonic acid cation exchangers, and allows tert-butyl acetylene to be obtained with high selectivity.

Sources of information

1. W. L. Collier and R. S. Macomber. tret-Butylacetylene Revisited. An Improved Synthesis. Methil Migration during Bromination. - J. Org. Chem., 1973, vol. 38, No. 7, p. 1367-1369.

2. W.H. Puterbaugh and M.S. Newman. Synthesis and some Reaktions of cis- and trans-Di-t-Butylethylenes. - J. Am. Chem. Soc., 1959, vol. 81, No. 7, p. 1611-1614.

3. P.D. Bartlett and L.J. Rosen. An Acetylenic Analog of Neopentyl Bromide; Evidence that the Hindrance to Displacement Reactions in Neopentyl Halides is Steric in Nature. - J. Am. Chem. Soc., 1942, vol. 64, N 3, p. 543-546.

4. P.V.Kazakov, E.I. Demina. Alkylation of acetylene with tert-butyl alcohol. - Izv. AN, Ser. Chem., 2002, No. 11, pp. 1978-1979.

Claims (4)

1. The method of producing tert-butylacetylene by the interaction of tert-butyl alcohol with acetylene in the presence of water, characterized in that the acid is used as a catalyst, and the optimal water content in the liquid reaction mixture is from 10 to 50%. 2. The method according to claim 1, characterized in that sulfuric, phosphoric, trifluoroacetic acids, sulfonic acids, sulfonic acid cation exchangers are used as a catalyst. 3. The method according to claim 1, characterized in that tert-butylacetylene is isolated continuously during the condensation of tert-butyl alcohol with acetylene. 4. The method according to claim 1, characterized in that tert-butylacetylene is isolated by distillation after condensation of tert-butyl alcohol with acetylene.