JPS6054301B2 - Alkyl carbazate production method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for producing alkyl carbazates represented by the general formula NH2NHC00R(I) (wherein R represents a lower alkyl group),
Specifically, a method for industrially inexpensively and advantageously producing alkyl carbazates from hydrazine hydrate and alkyl chloroformates, characterized by using 1 equivalent of mineral acid per mole of hydrazine as an acid binder. It is.

The compounds according to the present invention are useful compounds as intermediates for pharmaceuticals or agricultural chemicals, and are generally produced by a method of manufacturing from hydrazine hydrate and methyl carbonate (C, A, i, 3056
, BerN4! , 2183-2195) and a method for producing hydrazine hydrate and alkyl chloroformate in an aqueous solution without using an acid binder (C, A, i) 364; Be
r) Outside 3018-3027) are known. The former has a high yield of 90-95%, but alkyl carbonates have a higher yield than alcohols and 1% compared to alkyl chloroformates.
Not only is a molar excess required, but it also requires pollution countermeasures such as an operation to recover alcohols produced as a by-product from the reaction with hydrazine hydrate or activated sludge treatment, so it cannot be said to be an industrially superior method. .

The latter method uses alkyl lorformates, which are cheaper than alkyl carbonates, but the yield is as low as 49%, and cannot be said to be an industrially advantageous method. The present inventors conducted a detailed study on the latter method, which uses industrially inexpensive raw materials as a method for producing alkyl carbazates, and found that a known method in which an alkyl chloroformate is directly reacted with hydrazine hydrate is known. It was confirmed that in this method, N-N'-alkoxycarbohydrazides were produced as by-products, which caused a significant decrease in yield.

; The present inventors selectively reacted monomineral acid salts of hydrazine obtained by adding 1 equivalent of mineral acid per mole of hydrazine to hydrazine hydrate with alkyl chloroformates. happened, totally N-N
The present invention was completed by discovering that highly pure alkyl carbazates can be obtained in high yields without the by-product of ``-alkoxycarbohydrazides.

In carrying out the present invention, water and 1 equivalent of mineral acid per mole of hydrazine are added to hydrazine hydrate, and the temperature is lowered to 3.
(sub) Hereinafter, an alkyl chloroformate is added and reacted, preferably while maintaining the temperature at 10 to 15°C.

As the mineral acid, concentrated hydrochloric acid, concentrated sulfuric acid, diluted hydrochloric acid, diluted sulfuric acid, etc. are used, and the reaction is carried out for 1 to 5 hours.

The desired product is obtained with a yield of 9.5% or more and is usually used as is.
When it is to be isolated for use in the next reaction, the solvent is concentrated under reduced pressure, cooled, and the precipitated crystals are filtered off and dried to obtain substantially pure alkyl carbazate.

Moreover, hydrazine can also be used instead of hydrazine hydrate. Next, the method of the present invention will be explained in more detail with reference to Examples.

Example 1 Production of methyl carbazate 19.4 y (0.33 mol) of 85% hydrazine hydrate, 100 ml of water and 33.3 y (0.33 mol) of concentrated hydrochloric acid were mixed and stirred while maintaining the temperature at 13°C. At the same time, 28.35y (0.30 mol) of methyl chloroformate was added dropwise over a period of 20 minutes.

After the completion of the dropwise addition, stirring was continued for 2 hours at 10'C, the reaction solution was concentrated under reduced pressure, and the residue was dried under reduced pressure to obtain a decomposition point of 151-1.
37.6 years of white plate-like crystals of methyl carbazate hydrochloride were obtained at 55°C. (Yield, 99.0%) Example 2 Preparation of methyl carbazate 85% hydrazine hydrate 5.87f (0.10 mol),
30 ml of water and 10.11y (0.10 mol) of concentrated hydrochloric acid were mixed, and 11.34f (0.12 mol) of methyl chloroformate was added thereto while maintaining the temperature at 15 (range).

After the completion of the dropwise addition, stirring was continued for about 5 hours at 15°C to complete the reaction. Quantified by TPF colorimetric method Yield: 99.1
%Note, TPF: (Na3[Fe(CN)5NH3]Tr
isOdiumPentacyanOamineFer
rOate Example 3 80% Hydrated Hydrazine 6.23f (
0.0997 mol) and 20% sulfuric acid 24.6f (0.05 mol)
02 mol) and 30 ml of water, and the temperature was set to 15°C.
Methyl formate 11.05f(a). 1
155 mol) is added.

After the completion of the dropwise addition, the reaction was completed while stirring at 15° C. for about 5 hours. Determined by TPF colorimetric method Yield, 94.1% Example 4 Preparation of ethyl carbazate 18.8y (0.30 mol) of 80% hydrated hydrazine, 100 ml of water and 30.3 V (0.30 mol) of concentrated hydrochloric acid 3 mol) of ethyl chloroformate while keeping the temperature at 15°C.
Add 2.6f (0.30 mol) in two batches.

Claims (1)

[Claims] 1. When reacting an alkyl chloroformate represented by the general formula ClCOOR (in which R represents a lower alkyl group) with hydrazine hydrate, 1 equivalent of hydrazine is used as an acid binder for 1 mole of hydrazine. A method for producing an alkyl carbazate represented by the general formula NH_2NHCOOR (in the formula, R represents a lower alkyl group), which uses a mineral acid. 2. The manufacturing method according to claim 1, wherein the mineral acid is concentrated hydrochloric acid. 3. The manufacturing method according to claim 1, wherein the mineral acid is sulfuric acid. 4. The production method according to claim 1, 2 or 3, wherein the alkyl chloroformate is methyl chloroformate.