Ester with diazoethane

Diazomethane would be a reasonable candidate for simultaneous methylator of carboxylic and phenolic functions (both acidic), were it not for its reputation for erratic behavior toward phenolic groups. However, satisfactory results were reported [226] in the conversion of acids such as homovanillic to the corresponding ethyl ether-esters with diazoethane, CH CHNj. This reagent is specific for carboxylic and... 

As far as quantitative chemical derivatization GC analysis is concerned, it is necessary to mention especially the work of Gehrke and his collaborators, who specified the fundamental concepts of quantitative GC analysis combined with the chemical derivatization of sample compounds and applied them to the accurate determination of the twenty natural protein amino acids and other non-protein amino acids as their N-TFA-n-butyl esters [5 ], the urinary excretion level of methylated nucleic acid bases as their TMS derivatives [6], TMS nucleosides [7] and other investigations. Further examples include a computer program for processing the quantitative GC data obtained for seventeen triglyceride fatty acids after their transesterification by 2 NKOH in n-butanol [8], a study of the kinetics of the transesterification reactions of dimethyl terephthalate with ethylene glycol [9] and the GC-MS determination of chlorophenols in spent bleach liquors after isolation of the chlorophenols by a multi-step extraction, purification of the final extract by HPLC and derivatization with diazoethane [10]. 

The ester cleavage of fenitrothion leads to the formation of the metabolite 3-methyl-4-nitrophenol (MNP). Shafik et al. used GC-ECD for the detection of MNP in occupationally exposed subjects. Sample preparation involved extraction with diethyl ether, derivatization with diazoethane and purification on silica gel columns. The LOD was determined as 50 pgL with a recovery of 88-98%. 

Etbyl-3-nitrobenzoate, monoclinic prisms, mp 47°, bp 296° It may be prepd by saturating an ale soln of the acid with. HCl gas from the acid salt of 3 nitrobenziminoethylether from the 3-nitro acid and diazoethane and from the >nitro benz in bulling abs ale and HCl gas Ref Beil 9, 378, (151), (154) [248] Etbyl 4-nitrobenzoate, pi tits (from ale), mp 57°. It may.be prepd from the acid in ale in the presence of HCl, from the methyl ester and excess ale in the presence of KOCH3 Ref Beil 9, 390 [258]... 

Methods have been developed for obtaining other non-methyl esters. In addition to simpler techniques these methods were aimed at increasing the sensitivity and volatility and, sometimes, decreasing the volatility (for lower acids with high volatihty) and improving the separation and selectivity of determination. Other workers [174—176] have described the application of diazoethane, diazopropane, diazobutane and diazotoluene to obtain esters. Solutions of higher diazoalkanes are more stable and less explosive than diazomethane solutions. 

It is noteworthy that labeling is often carried out by reactions that normally have only academic interest or that are preparatively unimportant because of their demands on money and labor. For example, one is hardly likely to prepare ethanol by reaction of diazoethane with carboxylic acid and subsequent hydrolysis of the resulting ester, yet this reaction has proved definitely useful5 for the synthesis of deuterated ethanol, in the sense ... 

Reaction 33 carried out in HTO/TO is also a route for the introduction of tritium into the methylene group of esters. Diazoethane readily exchanges (lmin) its 1-H with NaOD/D20 solution at 4°C. Reaction of partially deuterated CH3CDN2 with p-02NC6H4C02D gave (l-2H)-ethyl and (l,l-2H2)-ethyl 4-nitrobenzoate. 

In the absence of acid catalysis, diazomethane reacts only with carboxylic acids (pA a 4—5) and phenols (pAa 9-10), but has no influence on aliphatic OH groups. Besides CH2N2, some more complex diazocompounds (diazoethane, diazotoluene) have been recommended for the synthesis of ethyl and benzyl esters, respectively. For the synthesis of baizyl (or substituted benzyl) esters, some special reagents have also been proposed, e.g., AA -dicyclohexyl-O-benzylurea and 1 -(4-methylphenyl)-3-benzyltriazene. 

The addition of diazoethane to benzylidenemalonic esters and a-cyano-acrylic esters gives 5-methyl-l-pyrazoIines (90), " Pyrolysis of these compounds is similar to that of the derivatives without a 5-methyl group, olefin formation occurring with migration of a 4-substituent to the 5-position. 

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