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Unformatted text preview: 17.1 Nomenclature longest chain with –CH=O group is base name for aldehydes, replace –e of corresponding alkane with –al C in –CH=O must be numbered 1 -dial is used when two aldehyde functions exist substituents named usual way when –CH=O (formyl group) attached to ring, ring name followed by – carbaldehyde higher oxidation state takes precedence when multiple O containing groups exist (aldehyde over alcohol) for ketones, replace –e with –one number chain so that formyl C gets lowest number possible carbonyl C in ring structure is automatically numbered 1 ketones take precedence over alcohols, double bonds, halogens, and alkyl groups aldehydes take precedence over ketones in this case, ketone named as oxo-substituent can also name ketones by naming groups attached to carbonyl group and then adding ketone (ex: ethyl propyl ketone) 17.2 Structure and Bonding: The Carbonyl Group carbonyl bond geometry is coplanar bond angles of about 120° C=O bond length shorter (122pm) than C-O bond (141pm) bonding described by sp2 hybridization carbonyl group makes compounds polar makes C electrophilic with carbocation character planar arrangement of bonds O is partially negative and weakly basic alkyl subtituents stabilize carbonyl group like carbocations therefore ketone carbonyl more stable than an aldehyde carbonyl 17.3 Physical Properties aldehydes and ketones have higher BPs than alkenes because of dipole moments but have lower BPs than alcohols because two carbonyl groups cannot hydrogen bond carbonyl group can form hydrogen bonds with protons of OH groups (more soluble in water than alkenes, less than alcohols) 17.4 Sources of Aldehydes and Ketones most important rxns are oxidation of primary alcohol to aldehyde and secondary alcohol to ketone combined with rxns that yield alcohols give many tools for synthesis SEE TABLE 17.1 FOR L IST OF REACT IONSSEE TABLE 17....
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