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Alcohols

Alcohols. Nomenclature of alcohols: IUPAC system نذكر اسم alkane و نحذف منه حرف e و نستبدله ب ol و في حالة الترقيم نعد من الطرف الذي يعطى مجموعة OH أقل ترقيم. في حالة alkene or alkyne نحذف حرف e و نستبدله ب ol و في حالة الترقيم نعد من الطرف الذي يعطى مجموعة OH أقل ترقيم.

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Alcohols

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  1. Alcohols Nomenclature of alcohols: IUPAC system نذكر اسم alkaneو نحذف منه حرف eو نستبدله بol و في حالة الترقيم نعد من الطرف الذي يعطى مجموعة OH أقل ترقيم

  2. في حالة alkene or alkyne نحذف حرف e و نستبدله ب ol • و في حالة الترقيم نعد من الطرف الذي يعطى مجموعة OH أقل ترقيم Examples

  3. Common names • نذكر اسم alkylالمتصلة ب OH ثم نكتب كلمة alcohol Examples

  4. Carbinol method • تعتمد هذه الطريقة على أن CH3OH يسمى ب Carbinol و تسمىalcohols كمشتقات منه بذكر أسماء alkyl المستبدلة بدلا من ذرات الهيدروجين في مجموعة CH3 ثم نكتب كلمة Carbinol • Examples

  5. Examples of nomenclature

  6. 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.

  7. 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

  8. Preparation of alcohols • a) Preparation of 1ry alcohol1. • 1- Hydrolysis of alkene 2. Hydrolysis of alkyl halide

  9. 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

  10. 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 CH3CH2OH CH3COOCH2CH3 + LiAlH4 2 CH3CH2OH Also Na/ROH can reduce esters to 1ry alcohol

  11. 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

  12. b) Preparation of secondary alcohols Secondary alcohols are prepared from Grignard reagent and aldehyde other than formaldehyde.

  13. c) Preparation of tertiary alcohols Tertiary alcohols are prepared from Grignard reagent and ketones.

  14. 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

  15. Dehydration of alcohols See alkene Formation of esters e.g. CH3CH2OH + CH3COOH CH3COOCH2CH3 + H2O Ethanol acetic acid Ethyl acetate • Differentiation between different types of alcohols • By oxidation • 1ry alcohol oxidize to give aldehyde or acid

  16. 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

  17. Examples of iodoform equations

  18. Mechanism of iodoform • (a) For alcohols

  19. (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

  20. Ethers • Nomenclature of ethers IUPAC nomenclature • تسمى RO ب Alkoxyو تتم التسمية باعتبارROفرع في سلسلة الالكان E.g. CH3O- CH3CH2O- CH3CH2CH2CH2O- Methoxy Ethoxy Butoxy Examples of ethers CH3OCH2CH2CH3 CH3CH2OCH2CH3 1-Methoxypropane Ethoxyethane

  21. Comman Nomenclature • نذكر أسماء الألكيل المتصلة بذرة الأوكسجين ثم نكتب كلمةether • Examples CH3CH2OCH2CH3 C6H5OCH3 (CH3) 3 C-OCH2CH3 Diethyl ether methyl phenyl ether t-Butyl ethyl ether (Anisole)

  22. Preparation of ethers • From alcohols Wiliamson synthesis It is reaction between alkoside and alkyl halide E.g. preparation of diethyl ether

  23. Question • Show how could you prepare the following ethers: (a) Anisole (phenyl methyl ether) (b) t- butyl ethyl et Answer

  24. 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.

  25. Reaction of ethers • Reaction with acid halide

  26. Cyclic ethers • تسمى Cyclic ethers ب alkene oxide أو نحدد رقمي ذرتي الكربون المتصلتين بذرة الأوكسجين و يسميا ب epoxy و ينسبا ل alkane

  27. 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.

  28. Examples

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