Carbinolamines

Isolation of the carbinolamine intermediate (66) is possible in the reaction of 2-amino-5-nitrothia2ole with acetaldehyde (Scheme 46) (216). 

The December 2000 issue of the Journal of Chemical Education (pp 1644-1648) contains an article entitled Carbinolamines and Geminal Diols in Aqueous Environmental Organic Chemistry... 

Write the structure of the carbinolamine intermediate and the imine product formed in the reaction of each of the following... 

The carbinolamine is formed by nucleophilic addition of the amine to the carbonyl group Its dehydration gives the imine product... 

Reaction with primary amines (Section 17 10) Isolated product is an imine (Schiff s base) A carbinolamine inter mediate is formed which undergoes de hydration to an imine... 

Reaction with secondary amines (Sec tion 17 11) Isolated product IS an en amine Carbinolamine intermediate can not dehydrate to a stable imine... 

Primary amines undergo nucleo philic addition to the carbonyl group of aldehydes and ketones to form carbinol amines These carbinolamines dehydrate under the conditions of their formation to give N substituted imines Secondary amines yield enamines... 

Presumably the species that undergoes reduction here is a carbinolamine an iminium ion derived from it or an enamme... 

Imines are formed by nucleophilic addition of a primary amine to the carbonyl group of an al dehyde or a ketone The key step is formation of a carbinolamine intermedi ate which then dehy drates to the imine... 

Carbinolamines are formed by nucleophilic addition of an amine to a carbonyl group and are intermediates in the for mation of imines and enamines Carbocation (Section 4 8) Positive ion in which the charge re sides on carbon An example is tert butyl cation (CH3)3C Carbocations are unstable species that though they cannot normally be isolated are believed to be intermediates in certain reactions... 

Auramine O (4,4 -bis-dimethylaminobenzophenone imine hydrochloride) [2465-27-2] M 321.9, pK 10,71 (free base), 9.78 (carbinolamine). Crystd from EtOH as hydrochloride, very slightly soluble in CHCI3, UV 434 (370) nm. The free base has m 136 after crystn from benzene. [J Chem Soc 1724 1949 Biochemistry 9 1540 1970]. 

General acid catalysis of the breakdown of the carbinolamine intermediate occurs by assistance of the expulsion of water. 

Work also prepared a series of carbinolamines and polyamines without a quinoline nucleus but, in other respects, conforming in type and range of molecular weight, with quinoline compounds known to possess plasmocidal activity. As none of these were active, it seems clear that the quinoline nucleus in the cinchona alkaloids and in certain synthetic anti-malarials is a potent factor in the production of plasmocidal action. Later the same author made (1942) a series of lepidylamine derivatives of the form R. Q. CHj. NH[CH2] . NEtj, which were found to be inactive, in spite of their similarity to the active examples of the type R. Q. NH[CH2] . NEt2 prepared by Magidson and Rubtzow. Rubtzow (1939) has also shown that an isomeride of dihydroquinine (II) with the quinuclidine nucleus attached via the carbinol group at C in the quinoline nucleus was inactive in an infection of Plasmodium prcecox in finches. 

---