2.4- dinitrophenylhydrazine, synthesis

S. Suggest mechanisms for all of the steps in this synthesis of 2,4-dinitrophenylhydrazine given in the chapter. 

The synthesis of a typical compound containing two units of dihydrobenzoin is shown as an example in Scheme 7 [26]. Reaction of 2,6-bis(bromomethyl)l,4-dimethoxybenzene 41 with the dibutyltin derivative of optically active dihydrobenzoin 59 yields a chiral podand 60 in 63%. Cyclization of 60 with the ditosylates of oligoethylene glycols, followed by oxidation with CAN and treatment with dinitrophenylhydrazine, affords the desired chiral dyed acerand 53. Some chiral azophenol acerands 51-58 are synthesized in a similar manner. 

Synthesis of l-hydroxy-6-nitrobenzotriazole from 2,4-dinitrophenylhydrazine has been described (Scheme 2.125) [647],... 

Ault, A. Three-step synthesis of 2,4-dinitrophenylhydrazine from benzene. J. Chem. Educ. 1965, 42, 267. 

The semicontinuous surfactant-free synthesis of a core/shell styrene/acrolein latex and its analysis for surface aldehyde functions are described. A calorimetric assay based on reaction with dinitrophenylhydrazine is compared with reduction by tritiated sodium borohydride and integration of aldehyde peaks in the proton NMR spectrum of the dissolved polymer. X-ray photoelectron spectroscopy confirmed the surface location of the aldehyde functions and the analytical reaction products. The three assay procedures were in reasonable agreement, suggesting all the aldehyde functions were accessible to aqueous reagents. Relevance to protein carriers is indicated. 21 refs. CANADA... 

One application of this reaction is the synthesis of 2,4-dinitrophenylhydrazine, a reagent that was once commonly used to prepare derivatives of aldehydes and ketones (Section 16.8B). 

Hydrolysis of the hydrazone followed by catalytic hydrogenation of the olefin and hydrogenolysis of the aryl bromide gave keto-phenol 25. Treatment of 25 with bromine in acetic acid, followed by reaction of the intermediate tribromide with 2,4-dinitrophenylhydrazine, gave 26. Hydrolysis of the hydrazone was followed by reduction of the enone to provide codeine (3). Demethylation of codeine provided morphine (1). This is a remarkable synthesis given tools that were available at the time. 

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