Girard reagent T

Isolation of aldehydes and ketonesAldehydes and ketones are readily separated from other organic compounds by heating a solution of the mixture in hexane or toluene with semicarbazide supported on silica gel (1 4 or 1 9) at about 70° for 12-18 hours. After filtration the carbonyl compound is regenerated from the solid phase by treatment with oxalic acid in a two-phase system, water and toluene or heptane. Girard T reagent (1, 410-411) supported on silica gel can also be used, but offers no advantages over supported semicarbazide. 

A valuable method of separating ketones from other neutral and water-insoluble compounds utilises the Girard-T reagent. (Section 4.2.30, p. 434). It reacts with the carbonyl compound to yield another quaternary ammonium salt ... 

Hydrazide, e.g., (carboxymethyl)trimethylammonium chloride hydrazide (Girard T reagent) [4, 56], andp-toluenesulfonhydrazide [36] and hydroxylamine [25]... 

The possibility of preliminary isolation of substances under analysis in the form of hydrazones is frequently utilized in the determination of ketosteroids in complex mixtures such as biological materials. In this form they are even sometimes subjected directly to GC analysis. Charransol et al. [378] determined androstanediol and testosterone in urine. After hydrolysis the sample was extracted with methylene chloride, evaporated and treated with Girard T reagent. Free hydroxysteroids were extracted with diethyl ether and... 

Alternatively, air is passed through 1-pm PTFE membrane and 1% sodium bisulfite solution. The solution is treated with chromotropic and sulfuric acid mixture. The color development due to formaldehyde is measured by a visible spectrophotometer at 580-mn absorbance (NIOSH 1984, Method 3500). In polarography analysis, a Girard-T reagent is used. Formaldehyde forms a derivative that is analyzed by sampled direct current DC polarography (NIOSH 1984, Method 3501). Auel et al. (1987) reported a similar electrochemical analysis of industrial air using an iridium electrode backed by a gas-permeable fluorocarbon-based membrane. 

Girard T-reagent TLC of the free carbonyl compounds or of their derivatives... 

Sulfenylation of C-7 imino carbanions was also exploited by Spitzer and Goodson (1973) in preparing 7a-methylthioamides 354-357, and by Ratcliffe and Christensen (1973) in their synthesis of cefoxitin. The former workers used lithium diisopropylamide in DMF (-78°C) to generate the Schiff base anion. Methylthiolation was performed with excess methoxy-carbonylmethyl disulfide. Liberation of the modified nucleus was achieved with Girard-T reagent in aqueous DMF. This series of methylthioamides was subsequently transformed with chlorine to the corresponding 7a-methoxyamides, presumably via the intermediacy of acylimines. 

Girard T reagent. The commercial reagent is recrystallized twice from ethanol. 

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