Reactions and characterisation of aromatic ketones

Aromatic ketones usually have relatively high boiling points, but distil with little or no decomposition. Many are solids. The vapours generally bum with a smoky flame. They react with the 2 4-dinitrophenyll hydrazine reagent (Section 111,74,f) or with the phenylhydrazine reagent 

The preparation of crystalline derivatives, including 2 4-dinitro-phenyl hydrazones, semicarbazones, oximes, phenylhydrazones and p-nitrophenylhydrazones can be carried out as described under Aromatic Aldehydes, Section IV,135. 

The melting points of various derivatives of a number of typical aromatic ketones are collected in Table IV, 148. 

Ketone B.P. M.P. 2 4-DlnP trophenyl-hydrazone Semi carbazone Oxime Phenyl- hydrazone p-Nltro- phenyl- hydrazone Other Derivatives 

Ketone BJ. MJ. 2 4-lMiil- trophenyl- hydnutone Semi- earbazone Oxime Phenjrl-hydnxone A mtro- phenyl liydrazone Other Derivatives 

A fairly general procedure consists in coupling a phenol or naphthol with a diazotised amine, reducing the product to an aminophenol or aminonaphthol, and oxidising the hydroxy compound with acid ferric chloride aolutiaa. This method is illustrated by the preparation of P (or 1 2)-naphthoquinone  

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For all the aldehydes tested, warming up the reaction mixture resulted in the appearance of new peaks, belonging to the corresponding 1,2-addition product, simultaneously with the disappearance of the cuprate signals. When aromatic ketones and 1,3-diketones or keto-esters were tested, formation of the corresponding ir-complexes was detected, albeit with on average lower conversion and stability with respect to the aldehydes. The only exceptions were acetophenone and benzophenone, for which no ir-complex was detected. Fluorenone 99, in contrast, formed a remarkably stable complex 99a (Scheme 36) that was also characterised for the first time by X-ray diffraction [136]. 

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