Bis 2,4-dinitrophenylhydrazone

Phthalaldehyde [643-79-8] M 134.1, m 54-56 , 55.5-56 , 58 , b 83-84 /0.8mm. Purified by steam distillation better by using super heated steam (at 175-180°) and efficient cooling. The distillate is saturated with Na2SO4 extracted exhaustively with EtOAc, dried (Na2SO4), filtered and evaporated. The residue is recrystd from pet ether (b 90-100°) [Belli and Tarbell Org Synth Coll Vol IV 808 1963]. It can be distd under vacuum. The bis-2,4-dinitrophenylhydrazone has m 278-280° [Hatt and Stephenson JCS 199 7952]. 

In contrast to those results, no useful discrimination between endo and exo hydroxyl groups could be found when employing ruthenium tetraoxide as an oxidant.213 Compounds 4,3, and 5 each affords the diketone 9 exclusively this was isolated as the bis(2,4-dinitrophenylhydrazone). 

Nitrogen derivatives of L-ascorbic acid are important because they have been used extensively for the vitamin s determination (J) in the form of the bis(2,4-dinitrophenylhydrazone) of dehydro-L-ascorbic acid (l). In addition, because of the commercial availability of L-ascorbic acid with a relatively low price as well as the widespread use of hetero-... 

Purify it by distilling and by recrystallising from pet ether. The bis-2,4-dinitrophenylhydrazone has m 221°... 

CXIIb ([aJu +8.0°), which gave a bis (2,4-dinitrophenylhydrazone), C21H24N8O10 (CXIIIb) (mp 192°-193°). Oxidation 169) of isojacone-cic acid itself gave carbon dioxide, acetaldehyde, and an oil [ Id +48.2° p-bromophenacyl ester, CivHigOsBr, mp 107°-108° ... 

Cvclohexane-l,4-dIone [637-88-7] M 112.1, m 76-77°, 78°, 79.5°, 79-80°, b 130-133°/20mm, dIj n 1.4576. Crystallise the dione from water, then benzene. It can also be recrystalhsed CHCl3/petroleum ether or Et20. It has been purified by distillation in a vacuum, and the pale yellow distillate which solidified is then recrystallised from CCI4 (14.3 g/100 ml) and has m 77-79°. The di-semicarbazone has m 231°, the dioxime HCl has m 150° (from MeOH/ C6Hg) and the bis-2,4-dinitrophenylhydrazone has m 240° (from PI1NO2). [Nielsen Carpenter Org Synth Coll Vol V 288 1973, IR LeFevre LeFevre J Chem Soc 3549 1956] [Beilstein 1IV 1986.]... 

Tellurium analogues have been prepared, and the reaction of the bis-(2,4->dinitrophenylhydrazone) (56) with selenium dioxide produces the interesting variant (57). ... 

Ascorbic acid is oxidized to dehydroascorbic acid by mild oxidizing agents. Dehydroascorbic acid undergoes spontaneous transformation into diketogulonic acid, slowly in ihildly acid solution, and very rapidly in solution at a pH below 1.0 and in a neutral or alkaline medium. When treated with 2,4-dinitrophenylhydrazine, dehydroascorbic acid and diketogulonic acid form a derivative, a bis-2,4-dinitrophenylhydrazone, in which... 

When the bis-2,4-dinitrophenylhydrazone of dehydroascorbic acid or diketogulonic acid is treated with 85% HjSOi, the derivative undergoes a molecular rearrangement and a highly stable, reddish brown product is formed which absorbs maximally at 500 to 550 and 350 to 380 m/i. The color obtained in this way is measured photometrically. 

The quantity of dehydroascorbic acid in a solution may also be determined by this method. The difference in values before and after reduction with hydrogen sulphide gives the amount of the dehydro-acid. This, however, is often complicated by the presence of other products of the reduction and a better method consists in the conversion of the dehydroascorbic acid to the bis-2,4-dinitrophenylhydrazone and photometric determination of the red colour produced on treatment of the bis-hydrazone with concentrated sulphuric acid . ... 

This procedure has also been adapted to differentiate between ascorbic acid, dehydroascorbic acid and diketogulonic acid . These latter two substances form bis-2,4-dinitrophenylhydrazones (CXII), (CXIII), in which the hydrazine residues are coupled to C-2 and C-3. The differentiation entails (i) the reduction of the dehydro form to ascorbic acid by hydrogen sulphide... 

These are used to qualify a group whose name begins with a (usual) numerical prefix, e.., bis-2,4-dinitrophenylhydrazone. They may also be used with composite names when the standard prefix would be misleading, e.g., NMe2 dimethylamino, but (NHMe)2 bismethylamino however, in the latter type of case di(methylamino) is equally satisfactory, at least in writing. 

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