Acetaldehyde from ethylamine

The purest available commercial samples of acetaldehyde, ethyl ether, and amines were purified by fractional distillation, either by conventional means or by using a spinning band column (Biichi). N-Methyl-diethylamine was prepared from diethylamine (4) and N,N-dimethyl-ethylamine from ethylamine (5). 

Diethylamine can also be prepared by reductive animation of acetaldehyde [from part (a)] with ethylamine. 

The condensation products of aldehydes with ammonia or amido-eoinpounds are easily reduced to amines in sulphuric-acid solution at lead cathodes. Thus hexamethylenetetramine yields methylamine (Knudson 2) ethylideneimine, ethylamine the base from acetaldehyde and ethylamine, diethylamine. Aromatic aldehydes behave similarly. The Farbwerke vorm. Meister,... 

Triethylamine was obtained in a yield of 16% by alkylating ethylamine drop by drop with acetaldehyde in a 1 2 molar ratio in a colloidal platinum solution at room temperature and 0.1 MPa H2.12 Benzyldiethylamine was prepared in a 31% yield from ethylamine, benzaldehyde, and acetaldehyde in a 1 1 1 molar mixture over a colloidal platinum in H20-AcOH-EtOH at room temperature and 0.3 MPa H2. The yield of the tertiary amine, however, was improved to more than 50% by alkylating ethylbenzy-lamine with acetaldehyde. 

Special reactions of hydrazides and azides are illustrated by the conversion of the hydrazide (205) into the azide (206) by nitrous acid (60JOC1950) and thence into the urethane (207) by ethanol (64FES(19)105Q) the conversion of the same azide (206) into the N-alkylamide (208) by ethylamine the formation of the hydrazone (209) from acetaldehyde and the hydrazide (205) and the IV-acylation of the hydrazide (205) to give, for example, the formylhydrazide (210) (65FES(20)259). It is evident that there is an isocyanate intermediate between (206) and (207) such compounds have been isolated sometimes, e.g. (211). Several of the above reactions are involved in some Curtius degradations. 

Derivatives of Formaldehyde and Acetaldehyde.—According to Tafel and Pfeffermann,1 the phenylhydrazones of aldehydes are readily converted into amines by reduction in sulphuric-acid solution at a lead cathode. Thus ethylidene phenyl-hydrazine yields about 60% of the theoretical percentage of pure ethylamine salt. The decomposition of glyoxime is more complicated. Besides ammonia and glyoxal and a small quantity of an acid (glyoxylic acid ) there is formed as the principal product the crystalline sulphate of a base, C2H802N2, the nature of which could not be determined with certainty. Ethylenediamine is not formed. Nor was a diamine obtained from methylglyoxime. 

Dimethylamine and trimethylamine (commercially available), 1,3,5-tri-N-methyl hexahydro-5-triazine (from reaction of formaldehyde and methylamine), tetramethylhydiazine (gift of B. J. Aylett), tetramethylmethylenediamine (from reaction of formaldehyde with dimethylamine), dimethyl- and diethylnitrosamine (from reaction of nitrous acid with the appropriate dialkylamine), diethylmethyl-amine (from reductive methylation of diethylamine), ethylethylideneamine (from reaction of ethylamine and acetaldehyde), and TMT and TET (from oxidation of the appropriate wnst/m-dialkylhydrazine). 

The A-ethyloxazolidinone 38 (Scheme 13.24) is obtained from L-serine by treating (5 )-serine methyl ester hydrochloride with EtsN, acetaldehyde and NaBH4 to give A-ethylamine 36. 

Ethylamine is not as readily metabolized as methyla-mine, and portions are excreted unchanged from the lung and in the urine. The metabolism of ethylamine is believed to occur in two stages. The amino group is initially dehydrogenated to an intermediate imine (ethyl imine), which reacts spontaneously with water, forming the corresponding aldehyde (acetaldehyde) and ammonia. The final metabolic products of acetic acid and urea are excreted in the urine. Ethylamine is a normal constituent of mammalian and human urine. 

A large family of other N-substituted homologues of 2,4-DMA were similarly prepared from the above ketone and sodium cyanoborohydride. Methylamine, ethylamine, propylamine, isopropylamine and hexylamine gave the corresponding N-alkyl homologues. The N,N-diethyl homologue was made from the primary amine, 2,4-DMA itself, with acetaldehyde and sodium cyanoborohydride but the product, N,N-diethyl-2,4-dimethoxyamphetamine, could not be converted into a crystalline hydrochloride salt. 

Ethanolamine ammonia lyase (EAL) converts ethanolamine (2-hydroxy-ethylamine) to acetaldehyde, with the loss of ammonia. The cobamide bovmd to the enzyme of Clostridium sp. was identified as a pseudocoenzyme B12 (37) [221] but a range of other adenosyl-cobamides are accepted as cofactors. The active enzyme is multimeric, has an apparent molecular mass of about 560-600 kDa, but further studies are much less advanced with EAL than those of the AdoCbl-dependent enzymes described above. From ESR studies [222], and the fact that the cobalamin binding motif (Gly-X-X-His-X-Asp) is absent [223], EAL was concluded to be a base-on B -dependent... 

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