5.4 Chemical Properties 5.4.1 alcohol
1. H of OH is very weakly acidic. The order of decreasing acidity is
2. 1° and 2° alcohols have at least one H on the carbinol C and are oxidized to carbonyl compounds羰基化合物.
They also lose H2 in the presence of Cu (300°C) to give carbonyl compounds. 氧化反应
3. Formation of alkyl halides. 取代反应
4. Intramolecular dehydration to alkenes . 分子内脱水 5. Intermolecular dehydration to ethers. 分子间脱水
6. Ester formation成酯.
7. Inorganic ester无机酯 formation
Similarly, alkyl phosphates are formed with H3PO4, phosphoric acid. 8. Alkyl sulfonates (esters of sulfonic acids), RSO2R′(Ar)
9. Oxidation.
Alcohols with at least one H on the carbinol carbon (1° and 2°) are oxidized to carbonyl compounds.
Aldehydes醛 are further oxidized to carboxylic acids羧酸, RCOOH.
To get aldehydes, milder reagents, such as the Jones (diluted chromic acid铬酸 in acetone丙酮) or Collins reagent (a complex of CrO3 with 2 mol of pyridine吡啶), are used.
5.4.2 Ethers １．碱牲
２．醚链断裂反应 ３．氧化反应
4．环氧乙烷的反应
2、醚键的断裂反应：
３.氧化反应
醚对氧化剂是稳定的，但醚放置时间久了，会被空气缓慢氧化，生成过氧化物。 醚分子中的a-H容易发生自由基反应
4. 环氧化合（epoxide） （一）结构
1,2-环氧乙烷是一个张力很大的环,因此比一般的环醚或开链醚的性质要活泼。 （二）反应
环氧乙烷的开环反应是亲核试剂对碳氧键进攻的亲核取代反应，在有机合成中有着很好的应用。 O2,AgCH2CH2CHCH2环氧乙烷的开环反应 制备： 2 OCl2,H2O
Ca(OH)2 CH2CH2OHCl
通过上述环氧乙烷的开环反应，可以得到邻二醇、醇醚、卤代醇、乙醇胺等含有二个官能团的化合物，这些化合物在工业上都有重要的用处。
如乙二醇单乙醚是常用的高沸点溶剂，氯乙醇是重要的有机合成中间体，乙二醇是合成“涤纶”的原料，也可作“抗冻剂”，乙醇胺是湿润剂、防锈剂。
Chapter 6 Aldehydes and Ketones
6.1 Introduction and Nomenclature
Carbonyl compounds have only H, R, or Ar groups attached to the carbonyl group.
Aldehydes have at least one H bonded to the carbonyl group; ketones have only R’s or Ar’s.
6.1.1 Aldehydes醛
IUPAC names the longest continuous chain including the C of —CHO and replaces -e of the alkane name by the suffix -al. The C of CHO is number 1. For compounds with two —CHO groups, the suffix -dial is added to the alkane name.
When other functional groups have naming priority, —CHO is called formyl.
Common names replace the suffix -ic (-oic or -oxylic) and the word acid of the corresponding carboxylic acids by -aldehyde.
Locations of substituents on chains are designated by Greek letters, for example:
The terminal C of a long chain is designated ω (omega).
6.1.2 Ketones酮
Common names use the names of R or Ar as separate words, along with the word ketone.
The IUPAC system replaces the -e of the name of the longest chain by the suffix -one.
In molecules with functional groups, such as —COOH, that have a higher naming priority, the carbonyl group is indicated by the prefix keto-. Thus, CH3—CO—CH2—CH2—COOH is 4-ketopentanoic acid.
Groups like
are called acyl groups酰基; for example,
CH3 is the acetyl group乙酰基.
Phenyl ketones are often named as the acyl group followed by the suffix -phenone
Problem 6.1 Give the common and IUPAC names for (a) CH3CHO,
(b) (CH3)2CHCH2CHO,
(c) CH3CH2CH2CHClCHO, (d ) (CH3)2CHCOCH3, (e) CH3CH2COC6H5, ( f ) H2CCHCOCH3.
(a) Acetaldehyde (from acetic acid乙酸), ethanal;
(c) α-chlorovaleraldehyde, 2-chloropentanal;
(d ) methyl isopropyl ketone, 3-methyl-2-butanone; (propiopheno)
(e) ethyl phenyl ketone, 1-phenyl-1-propanone ne); ( f ) methyl vinyl ketone, 3-buten-2-one.
The C=O group has numbering priority over the C=C group.
Problem 6.2 Give structural formulas for (a) methyl isobutyl ketone, (b) phenylacetaldehyde, (c) 2-methyl-3-pentanone, (d) 3-hexenal,
(e) β-chloropropionaldehyde.
Problem 6.3 Name the following compounds: (a) OHCCH2CH2CH2CH(CH3)CHO, (b) p-OHCC6H4SO3H, (c)
(d ) o-BrC6H4CHO.
(a) 2-Methyl-1,6-hexanedial.
(b) —SO3H takes priority over —CHO; thus, p-formylbenzenesulfonic acid.
(c) The corresponding acid is a cyclopropanecarboxylic acid, and -oxylic acid is replaced by -aldehyde:
2-methylcyclopropanecarbaldehyde.
(d) The -oic acid in benzoic acid is replaced by -aldehyde: o-bromo-benzaldehyde
(also called 2-bromobenzenecarbaldehyde).
一、状态与气味
甲醛室温下是气体，其他低级醛酮为液体。
低级醛有强烈的刺激味，中级醛和酮有水果香味。
二、沸点：
由于醛酮分子间不能形成氢键，故b.p比相应的醇低；由于极性大于醚，故b.p比醚高；烷烃是非极性分子，所以b.p最低。
判断分子量相近的不同化合物b.p高低的依据: 1、分子之间能否形成氢键.
2、分子是否具有极性且极性大小.
三、溶解度
羰基可与水形成分子间的氢键，低级醛、酮如：甲醛、乙醛、丙醛、丙酮可与水无限互溶。
四、相对密度
脂肪醛、酮相对密度小于1 芳香醛、酮相对密度大于1
6.2 Preparation
6.2.1 By Oxidation
1. 1° RCH2OH → RCHO and 2° R2CHOH → R2CO.
Alcohols are the most important precursors in the synthesis of carbonyl compounds, being readily available.
More complex aicohols are prepared by reaction of Grignard reagents with simpler carbonyl compounds.
Ordinarily MnO4- and Cr2O72- in acid are used to oxidize 2° R2CHOH to R2CO.
However, oxidizing 1° RCH2OH to RCHO without allowing the ready oxidation of RCHO to RCOOH requires special reagents.
(a) pyridinium chlorochromate (PCC)
(b) hot Cu (only with easily vaporized ROH);
(c) MnO2 (mild, only with allylic-type, RCHCHCH2OH, or benzylic-type, ArCH2OH, alcohols);
(d ) Na2Cr2O7/H2SO4/acetone (Jones reagent, which may permit RCOOH).
2. 1° RCH2X (X=Cl, Br, I) or —OSO2R′(Ar) +Me2S=O → RCHO
To prevent overoxidation of aldehydes, the very mild oxidant dimethyl sulfoxide, or DMSO, is used to react with 1° halides or sulfonates to give aldehydes. These reactants are in the same oxidation level as alcohols:
3. Alkyl Arenes: ArCH3ArCHO, ArCH2RArCOR
Benzylic CH3 and CH2 groups can be oxidized to groups at the same oxidation level as C=O.
These groups are then hydrolyzed to the C=O group.
4. Alkylboranes
The vinyl C with more H’s is converted into C=O.
Alkenes can also be transformed into dialkyl carbonylation-oxidation procedure.
carbonyls
by
a
5. Oxidative Cleavages氧化分解
Ozonolysis臭氧 of alkenes and cleavage of glycols二醇 afford carbonyl compounds.
These reactions, once used for structure determinations, have been superseded by spectral methods.
规律：每被氧化一次，氧化态就升高一步。
6.2.2 By Reductions of Acid Derivatives, RCOX, or Nitriles, RC=N
Acid chlorides, R(Ar)COCl, are reduced to R(Ar)CHO by H2 /Pd(S), a moderate catalyst that does not reduce RCHO to RCH2OH (Rosenmund reduction).
Acid chlorides, esters (R(Ar)COOR), and nitriles (RC=N) are reduced with lithium tri-t-butoxyaluminum hydride, LiAlH[OC(CH3)3]3, at very low temperatures, followed by H2O.
The net reaction is a displacement of X by :H
6.2.3 By Hydrolysis水解 and Hydration水合 of Compounds Oxidation Level
2. Alkynes
direct hydration and for net hydration through formation of vinylboranes by hydroboration.
6.2.4 By Friedel-Craft Acylations or Formylations of Arenes 通过弗里德尔工艺酰化或芳烃的甲酰化
6.3.5 By Acylation酰化 or Hydroformylation 氢甲酰化 of Alkenes
6.3.6 By Coupling Reactions偶联反应
2. Alkylation of 1,3-Dithianes with 1° RX or ROSO2Ar
