Schiff Base

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Related to Aldimine: Schiff base, Pyridoxal phosphate

Schiff base

[′shif ‚bās]
(organic chemistry)
RR′C=NR″ Any of a class of derivatives of the condensation of aldehydes or ketones with primary amines; colorless crystals, weakly basic; hydrolyzed by water and strong acids to form carbonyl compounds and amines; used as chemical intermediates and perfume bases, in dyes and rubber accelerators, and in liquid crystals for electronics.

Schiff Base

 

any one of a class of organic compounds with the general formula RR′C═NR″, where R and R′ represent hydrogen, an alkyl, or an aryl and R″ is an alkyl or aryl; in the latter case, Schiff bases are also called anils.

Schiff bases are crystalline or oily substances that are insoluble in water and soluble in organic solvents. They are weak bases, forming salts with acids in an anhydrous medium; in aqueous acid solutions they undergo hydrolysis to yield an amine and aldehyde. The majority of Schiff bases are stable in alkaline solutions. Schiff bases undergo hydrogenation to give secondary amines (RR′CH—NHR″) and add on many compounds containing mobile hydrogen, such as (β-dicarbonyl compounds, ketones, and imines. They are produced mainly by the condensation of aldehydes or ketones with primary amines.

The reaction was first completed by H. Schiff in 1864 (hence the name of the compounds). Schiff bases are valuable intermediate products of organic synthesis, for example, in the preparation of secondary amines and various heterocyclic compounds. The Schiff bases known as azomethine dyes are used for dyeing acetate and synthetic fibers; they are also used in color photography to reduce the photosensitivity of photographic emulsions.

References in periodicals archive ?
Imines [11], both aldimines and ketimines due to presence of carbon-nitrogen bond in their molecules, provides a potential site for chemical [12-13] as well as biological [14-15] activity, but very less work has been carried out on synthesis of [alpha],[beta]-unsaturated ketimines.
aldimines and ketimines) that become active upon reacting with atmospheric moisture and/or formulating with ASP-based secondary diamines.
The aim of the present work was to fill this gap and investigate the pinacol coupling of aldimines in the presence of mischmetall (Ce and La), Zn-Cu couple, and Dewarda alloy (50% Cu, 5% Zn, 45% Al).
3 mm) is inactive toward aldimines even under reflux.
Only the use of Zn-Cu couple for the asymmetric coupling of aldimines in DMF is documented [9].