Aldehydes, aromatic, melting point

You will be assigned one of the aromatic aldehydes shown in the following list. For each aldehyde, the melting points of the corresponding chalcone and the Michael/aldol product are given ... 

The melting points of the various derivatives of a number of typical aromatic aldehydes are collected in Table IV,135,... 

Structurally similar compounds often exhibit large differences in their melting points. This is illustrated in Figure 10.4.1 by comparing Tm of aromatic aldehydes and analogous carboxylic acid compounds. Structurally, the compounds differs by merely... 

Aromatic aldehydes and ketones react with diphenylketene at 120-160 °C to form aromatic olefins 227 . In these reactions, diphenylketene can be generated in situ from its 2 1 cycloadduct with quinoline, because cycloreversion occurs above its melting point (121 °C). 

This method can be used for identificati on when the acid formed can be isolated easily and when it is solid and has a sh arp melting point. This is the case mainly with aromatic aldehydes for the oxidation potassium permanganate, hydrogen peroxide, silver oxide, and other oxidants can be used. In the case of a mixture of aldehydes or if the acids are too soluble (aliphatic acids), the resulting acids can be identified by chromatography on paper (4) (see also p.259). 

For the GC separation of organic compounds (e.g., saturated and unsaturated hydrocarbons, aromatic compounds, alcohols, aldehydes) a new type of stationary phase has been proposed [160—162] crystallohydrates. The melting and decomposition points of the crystallohydrates determine the temperature range in which they can be used. 

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