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Alcohols Nomenclature of alcohols: IUPAC system نذكر اسم alkaneو نحذف منه حرف eو نستبدله ب ol و في حالة الترقيم نعد من الطرف الذي يعطى مجموعة OHأقل ترقيم في حالة alkene or alkyneنحذف حرف eو نستبدله ب ol و في حالة الترقيم نعد من الطرف الذي يعطى مجموعة OHأقل ترقيم Examples Common names alcohol ثم نكتب كلمةOH المتصلة بalkyl نذكر اسم Examples Carbinol method تعتمد هذه الطريقة على أن CH3OHيسمى ب Carbinolو تسمى alcoholsكمشتقات منه بذكر أسماء alkylالمستبدلة بدال من ذرات الهيدروجين في مجموعة CH3ثم نكتب كلمة Carbinol Examples Examples of nomenclature IUPAC name 2-propen-1-ol 2-Butanol 2-Methyl-1-Propanol Common name Allyl alcohol Sec-Butyl alc. Isobutyl alc. Ethyl methyl carbinol Isopropyl carbinol Carbinol method Vinyl carbinol Classification of alcohols According to number of OH groups • • • Monohydroxy alcohols: which contain one OH group e.g. ethanol Dihydroxy alcohols: which contain two OH group e.g. ethyleneglycol. Polyhydroxy alcohols: which contain more than two OH groups e.g. glycerol and carbohydrate. According to number of OH groups Monohydroxy alcohols are classified according to type of carbon bearing OH into three types: • 1ry alcohols: in which OH attach with 1ry carbon e.g. RCH2OH • 2nd alcohols: in which OH attach with 2nd carbon e.g. R2CHOH • t-alcohols : in which OH attach with tertiary carbon e.g. R3COH Preparation of alcohols a) Preparation of 1ry alcohol1. 1- Hydrolysis of alkene 2. Hydrolysis of alkyl halide E.g. conversion of benzene to benzyl alcohol 3. Reduction of carbonyl compound Reduction of aldehyde gives 1ry alcohol, while of ketone gives 2nd alcohol NaBH4 reduce C=O and not reduce C=C e.g. CH3CH=CH-CHO + NaBH4 CH3CH=CH-CH2OH Crotonaldehyde 2-Butenol 4. Reduction of acids and esters Acids and esters are reduced to 1ry alcohol by use of LiAlH4 E.g. CH3COOH + LiAlH4 CH3COOCH2CH3 + LiAlH4 CH3CH2OH 2 CH3CH2OH Also Na/ROH can reduce esters to 1ry alcohol Grignard reagent can be prepared as follow: Grignard reagent is used to prepare 1ry, 2nd, and t-alcohols a) Preparation of 1ry alcohol 1ry alcohol is prepared from Grignard reagent and formaldehyde b) Preparation of secondary alcohols Secondary alcohols are prepared from Grignard reagent and aldehyde other than formaldehyde. c) Preparation of tertiary alcohols Tertiary alcohols are prepared from Grignard reagent and ketones. Grignard reagent is used to synthesis many organic compounds e.g. Reactions of alcohols 1)Replacement of OH by halogen a) By reaction with HX ROH + HX RX + H2O X= I, Br and Cl e.g. CH3CH2OH + HBr CH3CH2Br +HOH b) By reaction with phosphorus halide R OH R OH 3 R OH PCl5 Cl R Cl + HCl + SO2 SOCl2 PCl3 + HCl + POCl3 R 3R Cl + H3PO3 Dehydration of alcohols See alkene Formation of esters e.g. CH3CH2OH + CH3COOH Ethanol CH3COOCH2CH3 + H2O acetic acid Ethyl acetate Differentiation between different types of alcohols 1. By oxidation a) 1ry alcohol oxidize to give aldehyde or acid [O] RCH2OH e.g. CH3CH2CH2OH propan-1-ol RCHO aldehyde [O] [O] RCOOH acid CH3CH2CHO propionaldehyde [O] CH3CH2COOH propionic acid Examples of oxidizing agent are K2Cr2O7/ H2SO4, KMnO4 and Cu/250oC b)2nd alcohol oxidize to give ketone c) Tertiary alcohols do not oxidize Iodoform test This reaction occurs with alcohols containing Also aldehydes or ketones containing CH3-CO can give iodoform Examples of iodoform equations Mechanism of iodoform (a) For alcohols (b) For aldehyde and ketones Only one aldehyde can give iodoform, this aldehyde is acetaldehyde, the mechanism of aldehyde and ketones are step 2, and 3 in alcohol. E.g. acetone Ethers Nomenclature of ethers IUPAC nomenclature فرع في سلسلة االلكانRO و تتم التسمية باعتبارAlkoxy بRO تسمى E.g. CH3OMethoxy CH3CH2OEthoxy CH3CH2CH2CH2OButoxy Examples of ethers CH3OCH2CH2CH3 1-Methoxypropane CH3CH2OCH2CH3 Ethoxyethane Comman Nomenclature ether نذكر أسماء األلكيل المتصلة بذرة األوكسجين ثم نكتب كلمة Examples CH3CH2OCH2CH3 C6H5OCH3 (CH3) 3 C-OCH2CH3 Diethyl ether methyl phenyl ether t-Butyl ethyl ether (Anisole) Preparation of ethers From alcohols Wiliamson synthesis It is reaction between alkoside and alkyl halide E.g. preparation of diethyl ether Question Show how could you prepare the following ethers: (a) Anisole (phenyl methyl ether) Answer (b) t- butyl ethyl et Observation: Alkyl halide must be primary or secondary because t-alkyl halide undergoes loss of HCl (elimination) so it gives alkene not ether e.g. Reaction of ethers Reaction with acid halide Cyclic ethers تسمى Cyclic ethersب alkene oxideأو نحدد رقمي ذرتي الكربون المتصلتين بذرة األوكسجين و يسميا ب epoxyو ينسبا ل alkane Preparation of cyclic ethers In case of unsymmetrical cyclic ethers, the product depends on the reaction condition In case of acidic medium, nucleophile goes to more steric carbon i.e. carbon containing less number of hydrogen. In case of basic medium, nucleophile goes to less steric carbon i.e. carbon containing great number of hydrogen. Examples