CH307629A - Process for the preparation of a monosubstituted hydrazine. - Google Patents

Description

  

  



  Process for the preparation of a monosubstituted hydrazine.



   Monosubstituted hydrazines, the hydrazine radical of which is not directly bound to an aromatic ring, have so far only been found either by relatively complicated detours, for example by condensation of hydroxylamine-O-sulfonic acid with alkylamines or by reduction and hydrolysis of the nitroso compounds of symmetrical dialkylureas, or by careful alkylation of hydrazine with low yields easily.



   As has now been found, such monosubstituted hydrazines can be obtained from readily available starting materials with good results if hydrazides of the general formula acyl-NH-NH2, in which. Aev] is an easily cleavable acyl radical, for example the carbomethoxy, carb iithoxy, formyl or acetyl group, conjoined with aliphatic, eyeloaliphatic, aromatic, araliphatic or heterocyclic aldehydes or ketones to give the corresponding N'-aylated hydrazones ,

      these are hydrogenated to the corresponding Nmonosubstituted and N'-acylated hydrazines and the latter treated with hydrolyzing agents.



   All three steps of the process can be carried out easily and with good yield. Two consecutive steps or all three can, if desired, be carried out in one operation without working up the intermediate products.



     Suitable solvents for the hydrazone formation are, in addition to excess aldehydes and ketones, which can be converted, in particular alcohols, such as methanol or ethanol, and they also form the preferred solvents for the hydrogenation. For example, platinum or palladium on carbon can be used as hydrogenation catalysts. The uptake of hydrogen usually takes place at room temperature or at a moderately elevated temperature and normal pressure with sufficient speed; Increasing the pressure accelerates the uptake of hydrogen.



   The hydrolysis can be carried out, for example, with a slight excess of alkaline agents, such as concentrated sodium hydroxide solution, potassium hydroxide solution, calcium hydroxide or barium hydroxide, as well as aqueous-alcoholic or alcoholic sodium hydroxide or potassium hydroxide solution. In the case of the hydrolysis of N-monosubstituted N'-carbalkoxy-hydrazines, only a small amount of alcohol needs to be added initially, since further alcohol is released as the hydrolysis proceeds. Acid hydrolysis, for example using mineral acids, is less advantageous.



   The acylhydrazines required as starting materials are easily accessible by treating hydrazine with suitable functional derivatives of the corresponding acids.



  Esters, for example alkyl formates and acetic acid esters, dimethyl carbonate and diethyl carbonate, are advantageous as functional derivatives since their use results in little or no diaylhydrazines as by-products, but acid chlorides can also be used if the procedure is appropriate.



   Aldehydes and ketones that can be used are not only those which, in addition to the carbonyl group, contain only one or two hydrocarbon radicals or simple heterocyclic radicals, but also other substituted compounds, provided their substituents are not undesirably changed by one of the three reactions mentioned above will.

   The process is not considered for the production of compounds with a readily hydrogenatable multiple bond; on the other hand, one can of course hydrogenate a double bond that is not desired in the end product in the second stage or, in the third stage, in addition to the cleavage of the N'-ayl group change the hydrolyzable group in the molecule Aldehydes and ketones include formaldehyde.



     Aeetaldehyde, propionaldehyde, butyraldehyde, valeraldehyde, glyoxylic acid, crotonaldehyde, acetone, butanone, pinacolin, cyelopentanone.



  Cyelohexanone, camphor, fenchone, benzaldehyde, p-chlorobenzaldehyde, salicylaldehyde, anisaldehyde, phenylacetaldehyde, cinnamaldehyde, acetophenone, butyrophenone, benzyl methyl ketone, furfural and nicotinaldehyde in particular.



   The monosubstituted hydrazines which have become easily accessible by the process according to the invention form valuable intermediate products for the production of insecticides, medicaments and dyes.



   The present patent is now a process for the production of isopropyl hydrazine. The process is characterized by dā one hydrazine of the formula
Acyl-NH-NH2, in which acyl denotes an easily cleavable aeyl radical, condensed with aeetone, the obtained aeetone-N'-acyl-hydrazone is hydrogenated to isopropyl-N'-aeyl-hydrazine and the latter is treated with a hydrolyzing agent.



  The known isopropylhydrazine obtained is a valuable intermediate.



   Example:
208 parts of hydrazine carboxylic acid ethyl ester are refluxed with 140 parts of pure acetone for 10 to 12 hours. The hydrazone crystallizes out on cooling.



  After recrystallization, it melts at 72 to 73¯ 144 parts of ethyl acetone hydrazone carboxylate are dissolved in 500 parts by volume of ethanol, 10 parts of a 5 percent platinum carbon catalyst are added and the hydrogenation is subjected. Hydrogen uptake can be accelerated by applying pressure and increasing the temperature.



  When it has ended, the catalyst is filtered off and the solution is fractionated. Under 11 mm pressure, the ethyl isopropylhydrazine carboxylate goes over at 95 to 16, the yield corresponding to 91% of theory.



   The ester is heated to 95 to 100 with a small excess of 30 percent sodium hydroxide solution (about 190 parts of alkali per 100 parts ester) with stirring, the reaction suddenly starting with the separation of sodium carbonate and the released alcohol beginning to evaporate. You can cook on it for another hour in the Rüek river. The isopropyl hydrazine can be removed from the cooled reaction mixture, for example by means of licher, and then purified by distillation. The yield is 95 oxo.

 

Claims (1)

PATENT CLAIM: Process for the preparation of isopropylhydrazine, characterized in that a hydrazine of the formula Acyl-NH-NH2, in which acyl denotes an acyl radical that can easily be split off, condensed with acetone, the acetone-N'-aeyl-hydrazone obtained is hydrogenated to isopropyl-N'-acyl-hydrazine and the latter is treated with a hydrolyzing agent.