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Synthesis method of carbamic acid tertiary alkyl ester
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A technology of tertiary alkyl carbamate and carbamate, which is applied in the field of synthesis of tertiary alkyl carbamate, can solve the problems of harsh reaction conditions, limitations, and low efficiency, and achieve the effect of low production cost and suitable for large-scale production
Inactive Publication Date: 2011-05-18
HANGZHOU ALLSINO CHEM
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As a unique class of carbamate, tertiary alkyl carbamate is an important amino precursor, but its potential application value is greatly limited due to the difficulty in synthesis
[0003] Most of the reported synthetic methods of tertiary alkyl carbamates use phosgene as a raw material and are prepared through multi-step reactions. These methods are difficult to be used in the large-scale synthesis of tertiary alkyl carbamates due to low efficiency and harsh reaction conditions.
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[0019] Add 15 grams of tert-butanol, 120 grams of dichloromethane, 33 grams of trichloroacetic acid and 13 grams of sodiumcyanate to the reaction flask in sequence, start stirring, and control the reaction temperature at 25°C. After 30 hours, add 40 ml of water, stirring for 15 minutes, static layering. The aqueous phase was separated and extracted once with 40 ml of dichloromethane. The organic phases were combined and washed with water. The organic phase washed with water was filtered to remove dichloromethane to obtain white solid tert-butyl carbamate (16.6 g, yield 71%, GC analysis main content 98.5%).
[0020] Trichloroacetic acidrecovery: remove as much water as possible from the water phase obtained above, then add 120ml of dichloromethane, dropwise add 11ml of concentrated sulfuric acid in an equimolar amount to trichloroacetic acid at about 15°C, after the acidification is completed, filter, and remove t...
[0022] 15 grams of tert-butanol, 120 grams of dichloromethane, 31 grams of recovered trichloroacetic acid, 2 grams of fresh trichloroacetic acid and 13 grams of sodiumcyanate were successively added into the reaction flask, stirring was started, and the reaction temperature was controlled at 25°C. After 30 hours, 40ml of water was added into the reaction bottle, stirred for 15 minutes, and separated into layers. The aqueous phase was separated and extracted once with 40 ml of dichloromethane. The organic phases were combined and washed with water. The organic phase washed with water was filtered to remove dichloromethane to obtain white solid tert-butyl carbamate (16.4 g, yield 70.1%, GC analysis main content 98.5%).
Embodiment 3
[0023] Embodiment 3: the synthesis of (1,1-dimethyl) propyl carbamate
[0024] 17.8 grams of (1,1-dimethyl) propanol, 120 grams of dichloromethane, 33 grams of trichloroacetic acid, and 13 grams of sodiumcyanate were sequentially added into the reaction flask, stirring was started, and the reaction temperature was controlled at 25°C. After 30 hours, 40ml of water was added into the reaction bottle, stirred for 15 minutes, and separated into layers. The aqueous phase was separated and extracted once with 40 ml of dichloromethane. The organic phases were combined and washed with water. The organic phase washed with water was filtered to remove dichloromethane to obtain (1,1-dimethyl)propyl carbamate (19.8 g, yield 76%, main content 98.5% by GC analysis) as a white solid.
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Abstract
The invention relates to a synthesis method of carbamic acidtertiaryalkyl ester. In most of the reported synthesis methods of carbamic acidtertiaryalkyl ester, the phosgene is taken as a raw material to prepare the carbamic acidtertiaryalkyl ester by multi-step reactions, and the methods are hard to be used for the scale synthesis of the carbamic acid tertiary alkyl ester due to low efficiency and exacting reaction conditions. According to the technical scheme of the invention, the synthesis method of carbamic acid tertiary alkyl ester comprises the following steps of: reacting isocyanate with tertiary alcohol in an organic solvent in the presence of acid catalysis, separating and purifying the generated organic phases including the carbamic acid tertiary alkyl ester after the reaction is finished, and recovering the catalyst acid from the generated water phase. In the invention, because the conventional organic acid is taken as the catalyst to enable the isocyanate and the tertiary alcohol to be subjected to the catalytic reaction, the synthesis method has low production cost; and the organic acid is recovered with the recovery rate of 90-98%, an economical and practical synthesis method is provided for the carbamic acid tertiary alkyl ester, and the synthesis method is very suitable for the scale production.
Description
technical field [0001] The present invention relates to organic compound, specifically a kind of synthetic method of tertiary alkyl carbamate. Background technique [0002] Carbamates are an important class of organic intermediates, widely used in the synthesis of pesticides, medicines and other important organic compounds. As a unique class of carbamate, tertiary alkyl carbamate is an important amino precursor, but its potential application value is greatly limited due to the difficulty in synthesis. [0003] Most of the reported synthesis methods of tertiary alkyl carbamates use phosgene as a raw material and are prepared through multi-step reactions. Due to low efficiency and harsh reaction conditions, these methods are difficult to be used in the large-scale synthesis of tertiary alkyl carbamates. Contents of the invention [0004] The technical problem to be solved by the present invention is to overcome the defects in the above-mentioned prior art, and provide an ec...
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