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Chapter 9 Alcohols, Ethers and phenols. 9.1 IUPAC Nomenclature of Alcohols, Ethers and Phenols 9.1.1 Naming Alcohols 9.1.2 Naming Phenols 9.1.3 Naming Ethers 9.2 Preparation of alcohols,Ethers and Phenols 9.2.1 Preparation of alcohols
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Chapter 9 Alcohols, Ethers and phenols 9.1 IUPAC Nomenclature of Alcohols, Ethers and Phenols 9.1.1 Naming Alcohols 9.1.2 Naming Phenols 9.1.3 Naming Ethers 9.2 Preparation of alcohols,Ethers and Phenols 9.2.1 Preparation of alcohols A. Preparation of alcohols by reduction of carbonyl compounds (1) Hydrogenation of aldehydes and ketones by catalysis of metals (2) Reduction of carbonyl compounds by metal hydrides B. Preparation of diols
9.2.2Preparation of Ethers A. Ethers by intermolecular dehydration of alcohols B. Williamson Synthesis of Ethers 9.2.3 Preparation of phenols A. Laboratory synthesis B. Industrial synthesis 9.3 Reactions of Alcohols The sites of reactions of a Alcohol 9.3.1 Acidity and Basicity of Alcohols 9.3.2 Conversion of alcohols to ethers 9.3.3 Oxidation of alcohols A. Oxidation of primary alcohols B. Oxidation of secondary alcohols C. Oxidation of vicinal diols
9.4 Reactions of phenols 9.4.1 Acidity of Phenols 9.4.2 Electrophilic aromatic substitutions 9.4.3 Acylation of phenols Fries rearrangement 9.4.4 Kolbe-Schmitt reaction 9.4.5 Preparation of aryl ethers 9.4.6 Cleavage of aryl ethers by hydrogen halides 9.4.7 Claisen rearrangement of allyl aryl ethers 9.4.8 Oxidation of phenols: Quinones
9.5 Reactions of Ethers 9.5.1 Acid-catalyzed cleavage of ethers 9.5.2 Preparation of epoxides A.Epoxidation of alkenes by reaction with peroxy acids B. Conversion of vicinal halodrins to epoxides 9.5.3 Reactions of Epoxides A. Base-catalyzed ring opening B. Acid-catalyzed ring opening
Acetyl halides 酰卤 Esters 酯 Carboxylic acid anhydrides 酸酐 Amides 酰胺 Y Compounds with O-containing functional groups Alcohol Ether Phenol Aldehyde Ketone 醇 醚 酚 醛 酮 Alcohol Ether Phenol Aldehyde Ketone 醇 醚 酚 醛 酮 Carboxylic Carboxylic acid acid derivatives 羧酸 羧酸衍生物 The interplay of these compounds is fundamental to organic chemistry and biochemistry
Class of Alcohols: Primary alcohols Secondary alcohols Tertiary alcohols Compounds that have hydroxyl group bonded to a saturated, sp3-C atom-Alcohols. Compounds that have hydroxyl group bonded to a aromatic ring-Phenols. Compounds that have a oxygen atom bonded to two carbon atom -Ethers Class of Ethers: Ethers Epoxides
Suffix: e ol 9.1 IUPAC Nomenclature of Alcohols, Ethers and Phenols P252,8.1 9.1.1 Naming Alcohols Common name: Alkyl + alcohol Substitutive name: • Number: begin at the end nearer • the hydroxyl group. Allyl alcohol (烯丙醇) tert-Butylalcohol (叔丁醇) Benzyl alcohol (苄醇) 2-Propen-1-ol (2-丙烯-1-醇) Phenyl methanol (苯甲醇) 2-Metyl-2-propanol (2-甲基-2-丙醇)
BHT 5-Chloro- 2-methyl- phenol (2-甲基-5-氯 苯酚) 1,4-Benzenediol Hydroquinone (对苯二酚) (氢醌) 1,2-Benzenediol Catechol (儿茶酚) (邻苯二酚) Ethyl glycol (乙二醇) 1,2-Ethanediol 1,3-Benzenediol Resorcinol (间苯二酚) ClCH2CH2CH2OH 3-Chloro-1-propanol (3-氯-1-丙醇) Glycerol(甘油) 1,2,3-Propanetriol 9.1.2 Naming Phenols Phenol is the base name: o-, m-, p-: substitutent 4-Methylphenol p-Methylphenol p-Cresol(甲酚)
Pyrogallol (连苯三酚) 1,3,5-benzenetriol (均苯三酚) 1-Naphthol α- Naphthol (1-萘酚) 2-Naphthol β- Naphthol (2-萘酚)
Symmetrical ethers (单醚) Unsymmetrical (Mixed) ethers (混醚) 9.1.3 Naming of Ethers P253 Functional class IUPAC names Tetrahydrofuran (THF) (四氢呋喃) Diethyl ether (乙醚) Anisole Methyl phenyl ether (茴香醚) (苯甲醚) CH3CH2OCH3 Ethyl methyl ether (甲乙醚) tert-Butyl phenyl ether (苯叔丁基醚)
Suffix:yl oxy 1,4-Dioxane 1,4-二氧六环 二 烷 Oxane 烷 Substitutive IUPAC Alkoxy (烷氧基) 1-Ethoxy-4-methylbenzene (4-甲基-1-乙氧基苯) 2-Methoxypentane (2-甲氧基戊烷) Cyclic ethers:
9.2 Preparation of alcohols, Ethers and Phenols 9.2.1 Preparation of Alcohols Transformation of the several functional groups to alcohols: P258,8.4 A. Preparation of Alcohols by Reduction of Carbonyl Compounds
p-Methoxy- benzaldehyde p-Methoxybenzyl alcohol(92%) (1) Hydrogenation of aldehydes and ketones by Catalysis of metals Aldehydes Primary alcohols Ketones Secondary alcohols
Sodium borohydride NaBH4 (硼氢化钠) Lithium aluminum hydride LiAlH4(LAH) (四氢铝锂) (2) Reduction of carbonyl compounds by metal hydrides P259, 8.5 Metal hydrides:
4,4-Dimethyl- 2-pentanone 4,4-Dimethyl- 2-pentanol(85%) Butanal Butanal 1-Butanol (87%) 1-Butanol (87%) • Reaction of NaBH4 with aldehydes • and ketones An aqueous or alcoholic solution
3,3-Dimethyl-2-butanone 3,3-Dimethyl-2-butanol Cyclopropanecarboxylic Acid (环丙基甲酸) Cyclopropylmethanol (环丙基甲醇)(78%) • Reaction of LiAlH4 with Aldehydes • and Ketones • Reaction of LiAlH4 with carboxylic acids • and esters
Benzyl alcohol (苄醇)(90%) Ethyl benzoate (苯甲酸乙酯) 1°Alcohols • Selective reduction: • NaBH4 does not reduce C=C, • and -COOH, -COOR。 • LiAlH4 does not reduce C=C, Characteristics of reactions:
Reduced by LiAlH4 Reduced by NaBH4 Ease of reduction Methyl 2-pentenoate 2-Penten-1-ol(91%)
1,2-Ethanediol Ethylene glycol 1,2-乙二醇(甘醇) 1,2-Propanediol Propylene glycol 1,2-丙二醇 NaBH4 LiAlH4 Solvents: H2O, ROH Et2O, THF • Solvents: LiAlH4 reacts violently with water. B. Preparation of diols Vicinal diols
Alkaline (碱性) OsO4 Osmium tetraoxide (四氧化锇) tert-butyl hydroperoxide (叔丁基氢过氧化物) Hydroxylation KMnO4 / OH- (cold) Syn-addition
9.2.2Preparation of Ethers A. Ethers by intermolecular dehydration of alcohols Substrate: Primary alcohols Acid-catalyzed Products: symmetric ethers P261, 8.6 B. The Williamson Synthesis of Ethers Sodium alkoxide, Alkyl halide and derivatives Mixed ethers
The reaction characteristic: • SN2 reaction • 2. The best substrate is primary alkyl halide
Alexander W. Williamson (1824-1904) Alexander W. Williamson was Born in London, England, and received his Ph.D. at the University of Giessen in 1846.His ability to work in laboratory was hampered by a childhood injury that caused the loss of an arm. From 1849,utill 1887, he was professor of Chemistry at University College, London.
Bonding in organic compounds at that time was thought to be of either the water type, as in alcohols, ROH, or of the radical type, as in ethers which would be given the formula RO. But Williamson, by his ether synthesis, showed that mixed ethers, with two different alkyl groups, could be prepared. Ethers thus has to have the water-type formula ROR', and oxygen had the equivalent weight of 8 but the atomic weight of 16. By this type of argument he established and rationalised the structures of many of the families of simple organic compounds. Thus, in 1850 he predicted the existence of acetic anhydride, which was prepared in 1851.We still have some examples of his early apparatus, and his copper pelicans, in which he prepared ether, are shown at right. When you realise the scale on which these reactions were carried out, and the fact that the pelican was heated over a charcoal brazier, it is remarkable that we do not seem to have records of catastrophic accidents taking place. Later on Williamson, again with people such as Liebig, was responsible for the introduction of much of the glassware which we are familiar with today, except that it was usually fitted together with corks rather than ground glass joints. Standard joints, blown in a mould, as we know them today did not come into use until the middle of the last (20th) century. Towards the end of his period as Head of Department, Williamson became very much involved in College and University politics, and his research suffered. This was the period when the other London colleges - Kings, Birkbeck, Queen Mary, what is now Imperial College, and so on were combined into a federal university, and presumably Williamson felt the need to fight the University College corner.
9.2.3 Preparation of phenols From aniline: A. Laboratory synthesis (80%) B. Industrial synthesis (1) Reaction of benzenesulfonic acid with NaOH Toluene p-Toluenesulfonic p-methylphenol acid (72%) 碱熔法
(2) Hydrolysis of chlorobenzene 卤苯水解 3. From cumene(枯烯) Friedel-Crafts alkylation Cumene hydroperxide (氢过氧化枯烯)
Cumene is oxidized to cumene hydroperoxide 异丙苯法 9.3.Reactions of Alcohols
Nucleophilic substitution • The sites of reactions of a Alcohol: Weak basicity Nu: Protona- tion Weak acidity Elimination Oxidation
Reversible protonated by strong acids to yield oxonium ions( 离子): 9.3.1 Acidity and Basicity of Alcohols Like water, alcohols are both weakly basic and weakly acidic. P256,8.3 As a weak base: An alcohol An oxonium ion As a weak acid: An alcohol An Alkoxide Hydronium ion(烷氧负离子) ion(水合离子) Acid (base) conjugate conjugate base acid
K > 1 Stroger acid + Stroger base Weaker acid + Weaker base In any proton-transfer process: Relative acidity: Relative basicity: P257, Table 8.1
P263.8.7 NaH, NaNH2 9.3.2Conversion of Alcohols to Ethers Dehydration
1,5-Pentanediol (1,5-戊二醇) Oxane ( 烷)(76%) • Characteristics of the reaction: • Condensation(缩合反应) • 2. Only for primary alcohols • 3. The temperature of condensation is lower than elimination. • 4. SN2 mechanism
3-Fluoropropanoic acid (3-氟丙酸) (74%) 3-Fluoro-1-propanol (3-氟-1-丙醇) 9.3.3 Oxidation of alcohols P 263 A. Oxidation of primary alcohols PCC reagent is soluble in CH2Cl2
Citronellol (香茅醇) Citronellal (82%) (香茅醛) [O] Secondary alcohols ketones PCC doesn’t attack C=C bond B. Oxidation of secondary alcohols Chromic acid H2CrO4
AgIO3 Cyclohexanol Cyclohexanone(85%) C. Oxidation of vicinal diols Vicinal diols react with HIO4, the C-C bond is broken to form carbonyl compounds Ch.P225,(3) AgNO3 is added to identify the vicinal diols
9.4 Reactions of phenols The sites of reactions Acidity Acylation Formation of aryl ethers Aromatic Electrophilic substitution
pKa = 18 pKa = 9.89 pKa = 4.74 pKa (25℃) Substi- tuents Substi- tuents pKa (25℃) o- m- p- -H -CH3 -Cl -NO2 -OCH3 9.89 9.89 9.89 3.96 0.38 2,4-Dinitro 2,4,6-Trinitro (picric acid) (苦味酸) 10.20 10.01 10.17 8.11 8.80 9.20 7.17 8.28 7.15 9.98 9.65 10.21 9.4.1 Acidity of Phenols P256,8.3 TABLE 1 The acidity constants of phenols
Electron - releasing group Acidity is decreased Electron – withdrawing group Acidity is increased pka = 10 Substituted phenols: Substuents on the position o- or p- Electron delocalization in phenoxide ion:
9.4.2 Electrophilic aromatic substitutions P266; Ch.P322,(2) A hydroxyl group is a very powerful activating substituent: Bromination: Sulfonation: Rate control Equilibrium control
9.4.3 Acylation of phenols Acylating agents: acyl halides and carboxylic acid anhydrides Ch.P319(丙) Phenolic Esters (酚酯) Fries rearrangement: Conversion of aryl esters to aryl ketones. (9%) p-hydroxylbenzopheone (对-羟基二苯酮)(64%) Phenol benzoate
9.4.4 Kolbe-Schmitt reaction: Carboxylaltion of phenols Sodium phenoxide CO2 Heated under pressure Acidified Salicylic acid Aspirin (阿斯匹林) (乙酰水杨酸) Salicylic acid (水杨酸)(79%)
9.4.5 Preparation of aryl ethers Williamson Method A Phenoxide anion A alkyl halide Alkylation of hydroxyl oxygen a phenol Why? Me2SO4-methylating agent
9.4.6 Cleavage of aryl ethers by hydrogen halides The bond of O-R was broken! The bond of C-O in phenols has partial double bond character
9.4.7 Claisen rearrangement of allyl aryl ethers Intramolecular reaction Heating allyl aryl ether The product is o-allylphenol Transition state
Claisen was professor in Aachen in 1890, Kiel in 1897 and Berlin in 1904. Several syntheses especially condensation reactions between aldehydes, ketones, and esters (1881-1890) are connected with Claisen´s name. He also carried out research on tautomerism and rearrangement reactions (Umlagerungsreaktionen) http://www.chemsoc.org/networks/enc/FECS/ Claisen.htm 19th Century Claisen, LudwigBorn: Köln (Germany), 1851 Died: Godesberg near Bonn (Germany), 1930
The sructures of quinones: Hydroquionoe p-Benquinone 9.4.8 Oxidation of phenols: Quinones (醌) P266
9.5 Reactions of Ethers P267,8.9 9.5.1 Acid-catalyzed cleavage of ethers Mechanism of the reaction:
Syn-addition Peroxy acids: Peroxyacetic acide (过氧乙酸) Peroxybenzoic acide (过氧苯甲酸) 9.5.2 Preparation of epoxides A. Epoxidation of alkenes by reaction with peroxy acids (过氧酸) B. Conversion of vicinal halohydrins (α-卤代醇) to epoxides
Intramolecular Williamson ether synthesis: 1. Anti-addition, 2. Inversion of configuration