Carbonyl compounds aldehydes and ketones

All carbonyl compounds contain an acyl fragment (RC=0) bonded to another residue. The carbonyl carbon atom is sp hybridised (three o-bonds and one Jt-bond) and, as a consequence, the carbonyl group is planar and has bond angles of around 120°. The C=0 bond is short (1.22 A) and also rather strong (ca. 690kJmol ). 

Keynotes in Organic Chemistry, Second Edition. Andrew F. Parsons. 

PhCOCHs is an aromatic ketone, CH3COCH3 is an aliphatic ketone, and cyclohexanone, (CH2)5CO, is an aUcycUc ketone (Section 5.1) 

As oxygen is more electronegative than carbon, the electrons in the C=0 bond are drawn towards the oxygen. This means that carbonyl compounds are polar and have substantial dipole moments. 

Carbonyl compounds show characteristic peaks in the infrared (IR) and NMR spectra (see Sections 10.4 and 10.5.2). A characteristic signal is also observed for the aldehyde hydrogen, RCHO, in the H NMR spectrum (see Section 10.5.1). 

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Unsaturated compounds undergo ozonization to initially produce highly unstable primary ozonides (15), ie, 1,2,3-trioxolanes, also known as molozonides, which rapidly spHt into carbonyl compounds (aldehydes and ketones) and 1,3-zwitterion (16) intermediates. The carbonyl compound-zwitterion pair then recombines to produce a thermally stable secondary ozonide (17), also known as a 1,2,4-trioxolane (44,64,125,161,162). 

Much of organic chemistry is simply the chemistry of carbonyl compounds. Aldehydes and ketones, in particular, are intermediates in the synthesis of many pharmaceutical agents, in almost all biological pathways, and in numerous industrial processes, so an understanding of their properties and reactions is essential. We ll look in this chapter at some of their most important reactions. 

The difference in behavior between aldehydes/ketones and carboxylic acic derivatives is a consequence of structure. Carboxylic acid derivatives have ai acyl carbon bonded to a group -Y that can leave as a stable anion. As soon a the tetrahedral intermediate is formed, the leaving group is expelled to general- a new carbonyl compound. Aldehydes and ketones have no such leaving grouj however, and therefore don t undergo substitution. 

The results of the reaction of carbonyl compounds, aldehydes and ketones, with NH phosphinous amides can be interpreted as occurring on the PH phos-... 

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