平成27年度有機化学IV 前半第一回目講義

平成27年度有機化学IV
前半第一回目講義
宮地弘幸
有機化学IV前半
1: 10/1
10/8
授業計画
カルボン酸I
東京出張につき休講
2: 10/15
カルボン酸II
3: 10/22
カルボン酸誘導体I
4: 10/29
カルボン酸誘導体II
5: 11/5
アミンI
6: 11/12
アミンII
7: 11/19
これまでの学習内容復習
8: 12/3
中間考査
カルボキシ基を有する医薬品
インドメタシン抗炎症剤
リピトール脂質低下薬
世界で最売れている医薬品
2
カルボン酸の命名
● ギ酸（C=0）と酢酸（C=1）のみｉ，慣用名が許容されている
● C=2以上のカルボン酸の命名は，対応するアルカンのeを取り, oic acid
を付加.
カルボン酸の命名
●カルボン酸の命名は，アルカン酸の形で示し，カルボニル炭素をC1と数え，
COOHを含む最長鎖を母核構造とする。
●官能基としてのカルボキシル基は，他の官能基より最優先である。
The carbonyl group and the functional groups of its derivatives take precedence in naming
over any other groups discussed so far:
カルボン酸の命名
●When other functional groups are present, the main chain is chosen to
include other functional groups as much as possible.
●Saturated cyclic acids are named as cycloalkanecarboxylic acids.
●Aromatic acids are named benzoic acids.
Dicarboxylic acids are referred to as dioic acids.
カルボン酸の構造
Formic acid is planar.
The molecular structure of formic acid is roughly planar, which is
characteristic of carboxylic acids in general.
カルボキシル基は高極性で，水素結合して二量化する
The carboxy function is strongly polar and forms hydrogen bonds to other
polarized molecules such as water, alcohols and other carboxylic acids.
Carboxylic acids up to butanoic acid are completely soluble in water.
As neat liquids, and even in fairly dilute solutions, carboxylic acids form
hydrogen-bonded dimers (6–8 kcal mol-1).
カルボン酸は対応する炭素化合物より，高融点沸点
Carboxylic acids have relatively high melting and boiling points due to
hydrogen bonding in both the solid and liquid states.
カルボキシル基とカルボニル基の共鳴
The smaller deshielding can be attributed to the extra resonance form
present in carboxylic acids:
カルボン酸は中程度の酸性を示す
Carboxylic acids have much lower pKa values than do alcohols.
The lowered pKa values are due to the electron-withdrawing effect of the positively
polarized carbonyl carbon and the resonance stabilization of the carboxylate group.
カルボン酸は中程度の酸性を示す
Two of the three resonance forms of the carboxylate ion are equivalent,
leading to a symmetrical ion with equal carbon-oxygen bond lengths (1.26
Å), midway between a carbon-oxygen double bond (1.20 Å) and a carbonoxygen single bond (1.34 Å).
カルボン酸の酸性度は置換基の性質で変化
The inductive effect of electron-withdrawing groups close to the carboxy group
causes an increase in acidity.
Three electron-withdrawing groups on the -carbon sometimes results in
acidity near that of some inorganic acids.
カルボン酸の酸性度
The dioic acids have two pKa values.
In ethanedioic and propanedioic acids,
the first pKa is lowered by the electronwithdrawing effect of the second.
In higher dioic acids, both pKa values are
close to monocarboxylic acids.
Carboxylate salts of carboxylic acids can be prepared by treatment of the
acid with a base, such as NaOH, Na2CO3 or NaHCO3. These salts are
much more water soluble than the corresponding acids.
Carboxylate salts are named by specifying the metal and then replacing “ic
acid” with “ate”.
Carboxylic acids may be protonated on the carbonyl oxygen.
The carbonyl oxygen of a carboxylic acid may be protonated by strong
acids to give alkyloxonium ions.
The carbonyl oxygen is more basic than the –OH group of alcohols due to
resonance stabilization of the alkyloxonium ion.
Note that the protonation reaction is not particularly strong.
カルボン酸の工業的合成
Formic acid and acetic acid are manufactured on a large scale industrially.
Other important industrial carboxylic acids include the two dicarboxylic
acids:
•Hexanedioic acid
•1,4-benzenedicarboxylic acid
Nylon
Plastics
Methods for Introducing the Carboxy Functional Group
Oxidation of primary alcohols and of aldehydes furnishes
carboxylic acids.
Primary alcohols oxidize first to aldehydes, which then may further oxidize
to carboxylic acids.
Oxidants include CrO2, KMnO4 and HNO3.
Nitric acid is often chosen as the oxidant because it is one of the cheapest strong
oxidants.
Organometallic reagents react with carbon dioxide to give
carboxylic acids.
Carbonation, or reaction of an organometallic reagent with CO2 (dry ice),
produces a carboxylate salt, which yields a carboxylic acid upon
protonation in aqueous acid.
A two step synthesis allows the conversion of an alkyl halide into the
corresponding carboxylic acid having one more carbon.
Nitriles hydrolyze to carboxylic acids.
A second method for preparing a carboxylic acid with an additional carbon is
through the synthesis and hydrolysis of a nitrile, RCN.
Nitrile hydrolysis is preferable to Grignard carbonation when the substrate
contains other functional groups capable of reacting with the Grignard
reagent (hydroxy, carbonyl, nitro).

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