Semicarbazide


Also found in: Dictionary, Acronyms, Wikipedia.

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 ?
3-HPA production experiments were carried out as per the experimental design in 100-ml Erlenmeyer flasks, containing 40 ml of production medium, supplemented with glucose (3.2, 3.6, 4.0), semicarbazide HCl (1.4, 1.8, 2.2), [K.sub.2]HP[O.sub.4,] (0.4, 0.7, 1.0) and pH was adjusted (6, 7, 8).
Semicarbazide protection from in vivo oxidant injury of vascular tissue by allylamine.
MAO-dependent oxidation was defined as sensitive to inhibition by 1 mM pargyline, whereas SSAO-dependent oxidation was abolished by 1 mM semicarbazide. Assays were started by addition of the labelled substrate and stopped by adding 50 [micro]L of 4 M HCl.
It was also observed that compounds with imino nitrogen substituted with a semicarbazide or amine ([R.sub.2] = -NHCON[H.sub.2] and N[H.sub.2]) exhibited potent antibacterial activity.
A solution containing 1a (4.3 mmol), semicarbazide hydrochloride (4.3 mmol) and anhydrous sodium acetate (4.3 mmol), in absolute ethanol (40 mL) was stirred at room temperature for 18 hrs.
Characteristics of the inhibitory action of 1, 1-dimethyl-4-(phenyl sulfonyl) semicarbazide (DPSS) on ethylene production in carnation (Dianthus ca13,oph.vllus L.) flowers.
On July 28, EFSA announced that semicarbazide (SEM) may have been found in certain foods packed in glass jars and bottles closed with metal lids sealed with plastic gaskets.
FSA chairman Sir John Krebs said: "There is considerable uncertainty about the possible risks from semicarbazide.
Summary: This study presents synthesis of new polythioamides prepared from dialdehyde, [4,4'-methylene bis(cinnamaldehyde)] (MBC) with ethylenediamine, 1,3-propylenediamine, semicarbazide, thiosemicarbazide and meso-stilbenediamine, in the presence of elemental sulfur by Willgeordt Kindler reaction.
In brief, aqueous solution (20 mL) of semicarbazide hydrochloride (1.11 g, 1.0 mmol) was added to aqueous solution (20 mL) of 2-acetyl pyridine (1.20 g, 1.0 mmol) in the presence of sodium acetate (1.36 gm, 1.0 mmol).