SU859366A1 - Method of preparing 2-alkoxy-2-methyl-1,3-dioxanes - Google Patents

Description

(54) METHOD FOR OBTAINING 2-ALKOXI-2-METHYL-1,3-DIOXANES

one

The invention relates to a new process for the preparation of 2-alkoxy-2-methyl-1, 3-dioxanes of the formula

en% E. a

where R is the lowest value;

R is a hydrogen atom or lower alkyl.

A method of producing 2-alkoxy-2-methyl-1, 3-dioxanes is known, which consists in that the trialkyl orthocetate is reacted with 1,3-diol in the presence of an acid catalyst in cyclohexane with heating to 80 ° C. The yield of the target product 61-65% 1.

The disadvantage of this method is that the trialkyl ortho-acetate is obtained by dissolving alkyl acetimidate hydrochloride in a 10-15-fold excess of absolute alcohol, followed by adding 10-15-fold excess of an absolute diethyl ether and heating the reaction mixture at 46 ° C. The yield of triapkyl ortho acetate is 7578% 2.

Therefore, the total yield of 2-alkoxy-2-methyl-1, 3-dioxane per alkyl acetimide hydrochloride is 45-50%. Moreover, in the process of obtaining the starting trialkyl / ortho-ietate, significant amounts of absolute alcohol and diztile ether are required, and at the stage of obtaining 2-alkoxy-2-methyl-1,3-dioxanes from

10 trialkyl orthoacetate an acid catalyst is required, which increases the corrosion of the apparatus and also complicates the isolation of the target product.

The purpose of the invention is to simplify the process and, as a result, increase the yield of the target product.

This goal is achieved by the fact that in the known method diol-1,3 formula

R.CH-C. "I-CHATI

20

BHON

Bh

where R. has the above, value, is subjected to interaction with alkylacetamide the hydrochloride of the formula

III

CMj-С

.

Claims (2)

where R is as defined above, 30-8 pentane media. The yield of the target product is 52-60%. Example. Obtaining 2 labels si-2-methyl-1,3-dioxane. A three-necked flask was charged with 24 g of methyl acetimidate hydrochloride (0.22 gm), 15.5 MP of 1,3-propanediol (0.22 gm) and 100 ml of pentane. The mixture is stirred at room temperature for 24 hours. At the end of the run, the formed NHjjCln is filtered off and the solvent is distilled off. The desired product was isolated by vacuum distillation. The yield of 2-methoxy-2-methyl1, 3-dioxane is 58%. T. Kip. 53 ° C (12 mHg), df 1.0387,, 4215, MRj,: you are 32.51; found 32.26. Calculated,%: C 54.53; H 9.15; Found: C 54.41; H 9.03. PRI mme R 2. In analogy to Example 1, ethyl imidimide hydrochloride and 1,3-butanediol are obtained in 55% yield of 2-ethoxy-2,4-dimethyl-1,3-dioxane. T. Kip. 77 ° C (20 mmHg), d20.9780, h, 1.4200, MRj,: calculated 41.78; found 41.40. Calculated,%: C 59.98; H 10.07 SwNub Oz Found;%: C 59.73; H 9.95. Limer 3. In the same way as Example 1, methyl acetimidate hydrochloride and 1,3-butanediol are obtained in a yield of 52% 2-methoxy 2,4-dimethyl-1,3-dioxane. T, kip. 75-7b C (20 mmHg), 9987, 4l91, MRj: calculated: 37.13; found 36.93. Calculated,%: C 57.51; H 9.65, 40g Found,%: C 57.37; H 9.51. PRI me R 4. Similarly, the use of 1 from ethyl imidate hydrochloride and 1,3-propydiol is obtained in a yield of .60% 2-ethoxy-2-methyl-1, 3-dioxane. So 61-63 C (15 mmHg), 1.0017, hi 1.4223, 37.16; found 37.05. Calculated,%: C 57.51; H 9.65 b-fH - | 40a Found:%: 57.35; H 9.48. The use of the proposed method provides, in comparison with the EXT method, simplification of the process technology, reducing the stage of preparation and one trialkyl orthoacetate, reducing the consumption of scarce reagents, such as absolute alcohol and diethyl ether, at the stage of obtaining similar trialkyl orthoacetate, as well as equipment corrosion by removing from the process and acid analyzers and increase the yield of the target product by 2-15%. The invention The method of producing 2-alkoxy-2-methyl-1, 3-dioxanes of the general formula 1 and C, OR, where R is lower alkyl; R is a hydrogen atom or a lower alkyl, using. 1,3 - diode and hydrocarbon solvent, in order to simplify the process, 1,3 - diol of formula II R-CH-CH-CHi where K has the above values, is subjected to interaction with alkyl acetimidate hydrochloride of formula III СЧЛ-С Vwace -, where R has the above value, in the environment of pentane. Sources of information taken into account in the examination 1.Elied E.L. and Nader F.W. Conformational Analysis XX. Synthesis of 1,3-Dioxanes with Axial Substituents at C-2. lACS, 1970, 3, §2, c. 584 (prototype). 2.Me Elvain S.M. and Nelson I.W. The Preparation of Ortolsters. lacs, 1942, 64, c. 1825.