Semicarbazide


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semicarbazide

[¦sem·i′kär·bə‚zīd]
(organic chemistry)
H2N‒NHCONH2 A reagent used to produce semicarbazones by reaction with aldehydes or ketones.

Semicarbazide

 

H2N—NH—CO—NH2, the hydrazide of carbamic acid. Semicarbazide occurs as colorless crystals; it has a melting point of 96°C (with decomposition) and is soluble in water and alcohol. Semicarbazide possesses chemical properties similar to those of hydrazine and hydrazine’s organic derivatives. Combined with acids, it yields salts, for example, semicarbazide hydrochloride (CH5N3O·HCl), with a melting point of 173°C); with aldehydes and ketones, it yields readily crystallizing semicarbazones, as seen in the reaction

R2C=O + H2NNHCONH2

→R2C=NNHCONH2 + H20

Semicarbazide readily condenses (for example, with β-diketones) to form heterocyclic compounds. It is obtained by, for example, the reaction of hydrazine with potassium cyanate (KOCN). Semicarbazide is used primarily in the identification of aldehydes and ketones.

References in periodicals archive ?
In contrast, we found the precolumn semicarbazide derivatization simple to perform, reliable, and with adequate sensitivity and precision for the routine measurement of PLP in plasma and red cells; it compared favorably with the methods reported by Vuilleumier et al.
Semicarbazide ISEM) emerged as a potential food risk in July 2003, when the European Food Safely Authority (EFSA) alerted Member States to its presence in some foods sold in jars.
EFSA panel chairman Dr Sue Barlow said: "The risk to consumers resulting from the possible presence of semicarbazide in foods, if any, is judged to be very small.
FSA chairman Sir John Krebs said: "There is considerable uncertainty about the possible risks from semicarbazide.
Chairwoman of the EFSA panel, Dr Sue Barlow, said: ``The risk to consumers resulting from the possible presence of semicarbazide in foods, if any, is judged to be very small.
Acrolein is the principal cytotoxic metabolite of the anticancer and arthritis drug cyclophosphamide and is the principal and most physiologically active metabolite of allylamine (15), which is metabolized intracellularly to acrolein via semicarbazide sensitive amine oxidase.
Semicarbazide protection from in vivo oxidant injury of vascular tissue by allylamine.
A wide range of toxic contaminants and residues, from pesticides to mycotoxins or dioxins are examined, including also polychlorinated biphenyls, polycyclic aromatic hydrocarbons, N-nitrosamines, heterocyclic amines, acrylamide, semicarbazide, phtalates and food packing migrating substances.
The scare centres on the discovery of semicarbazide in protective seals which, in trials with animals, has been linked to cancers, liver damage and even miscarriage and birth defects.