Concept Summary

Description and Properties

Nucleophilic Addition Reactions

Aldehydes   are terminal    functional  groups  containing  a   carbonyl    bonded  to  at  least   one

hydrogen.   In  nomenclature,   they    use the suffix  –al and the prefix  oxo–.   In  rings,  they    are

indicated   by  the suffix  –carbaldehyde.

Ketones are internal    functional  groups  containing  a   carbonyl    bonded  to  two alkyl   chains. In

nomenclature,   they    use the suffix  –one    and the prefix  oxo–    or  keto–.

The reactivity  of  a   carbonyl    (C=O)   is  dictated    by  the polarity    of  the double  bond.   The carbon  has a

partial positive    charge  and is  therefore   electrophilic.

Carbonyl-containing compounds   have    higher  boiling points  than    equivalent  alkanes because of

dipole  interactions.   Alcohols    have    higher  boiling points  than    carbonyls   because of  hydrogen

bonding.

Aldehydes   and ketones are commonly    produced    by  oxidation   of  primary and secondary   alcohols,

respectively.

Weaker, anhydrous   oxidizing   agents  like    pyridinium  chlorochromate  (PCC)   must    be  used    for

synthesizing    aldehydes,  or  the reaction    will    continue    oxidizing   to  the level   of  the carboxylic

acid.

Various oxidizing   agents  can be  used    for ketones,    such    as  dichromate, chromium    trioxide,   or

PCC because ketones are the most    oxidized    functional  group   for secondary   carbons.

When    a   nucleophile attacks and forms   a   bond    with    a   carbonyl    carbon, electrons   in  the π   bond    are

pushed  to  the oxygen  atom.

If  there   is  no  good    leaving group   (aldehydes  and ketones),   the carbonyl    will    remain  open    and is

protonated  to  form    an  alcohol.

If  there   is  a   good    leaving group   (carboxylic acids   and derivatives),   the carbonyl    will    reform  and

kick    off the leaving group.