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Organic Chemistry II CHEM 271

Organic Chemistry II CHEM 271. Chapter One Alcohols, Diols and Thiols. Nomenclature of Alcohols. CH 3. CH 3 CCH 2 CH 2 CH 3. OH. CH 3 CHCH 2 CH 2 CH 2 CH 3. OH. Functional Class Nomenclature of Alcohols( Common Names). Name the alkyl group and add "alcohol" as a separate word.

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Organic Chemistry II CHEM 271

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  1. Organic Chemistry IICHEM 271

  2. Chapter OneAlcohols, Diols and Thiols

  3. Nomenclature of Alcohols

  4. CH3 CH3CCH2CH2CH3 OH CH3CHCH2CH2CH2CH3 OH Functional Class Nomenclature of Alcohols( Common Names) • Name the alkyl group and add "alcohol" as aseparate word. CH3CH2OH Ethyl alcohol 1,1-Dimethylbutylalcohol 1-Methylpentyl alcohol

  5. CH3 CH3CCH2CH2CH3 OH CH3CHCH2CH2CH2CH3 OH IUPAC Nomenclature of Alcohols • Name as "alkanols." Replace –e ending of alkanename by -ol. • Number chain in direction that gives lowest numberto the carbon that bears the —OH group. CH3CH2OH Ethanol 2-Methyl-2-pentanol 2-Hexanol

  6. Name these: 2-methyl-1-propanol 2-butanol 2-methyl-2-propanol 3-bromo-3-methylcyclohexanol =>

  7. Unsaturated Alcohols • Number the chain in thedirection that gives the lowest number to the carbon that bears the OH group 4-penten-2-ol (old) pent-4-ene-2-ol =>

  8. Naming Priority • Acids • Esters • Aldehydes • Ketones • Alcohols • Amines • Alkenes • Alkynes • Alkanes • Ethers • Halides => Chapter 10

  9. Hydroxy Substituent • When -OH is part of a higher priority class of compound, it is named as hydroxy. • Example: => 4-hydroxybutanoic acid

  10. Classes of Alcohols • Primary: carbon with –OH is bonded to one other carbon. -CH2OH • Secondary: carbon with –OH is bonded to two other carbons. -CHOH • Tertiary: carbon with –OH is bonded to three other carbons. -COH=>

  11. =>

  12. Diols • Two numbers are needed to locate the two -OH groups. • Use -diol as suffix instead of -ol. 1,6-hexanediol => Chapter 10

  13. Glycols • 1, 2 diols (vicinal diols) are called glycols. • Common names for glycols use the name of the alkene from which they were made. 1,2-ethanediol 1,2-propanediol propylene glycol => ethylene glycol

  14. Glycrol • 1, 2,3 Triols are called glycrol>

  15. Thiols • Contains an –SH (sulfhydryl) group. • Is named by selecting the longest carbon chain that contain the -SH. We add -thiol to the name of the parent alkane. • Parent chain is numbered from the end nearest tothe -SH group. • Methanethiol Ethanethiol • CH3─S─H CH3─CH2─S─H

  16. Physical Properties of Alcohols • Alcohols are polar molecules (because of O-H and C-O). • 2. Have higher boiling point than Alkanes, Alkenes & Alkynes due to Hydrogen bonding involves oxygen of one molecule and hydrogen of another in alcohol molecules. • 3. As the molecular weight increase, boiling point decrease. • As the molecular weight increase, solubility in water decrease . • The solubility of alcohols in water is due to hydrogen bonding between alcohol and water molecules. • 6. They are weak acids (weaker than Phenol).

  17. PHYSICAL PROPERTIES OF ALCOHOLS, cont. The –OH group can hydrogen bond between alcohol molecules leading to relatively high boiling points. Hydrogen bonding in pure ethanol:

  18. PHYSICAL PROPERTIES OF ALCOHOLS The –OH group is polar and capable of hydrogen bonding. This makes low molecular weight alcohols highly soluble in water. Hydrogen bonding in a water-methanol solution:

  19. Acidity of Alcohols • pKa range: 15.5-18.0 (water: 15.7) • Acidity decreases as alkyl group increases. • Halogens increase the acidity. • Phenol is 100 million times more acidic than cyclohexanol! => Chapter 10

  20. Preparation of Alcohols by Hydration of Alkenes Water molecule add to double bond in accordance with Markovnikov’s rule

  21. Preparation of Alcohols by Grignard Reagents By reaction of grignard reagents with aldehydes and ketones to form Primary, Secondary and Tertialy Alcohols.

  22. Preparation of Alcohols by Reduction of Aldehydes and Ketone

  23. Preparation of Alcohols by reduction of Carboxylic acids and Esters

  24. Preparation of Alcohols from Epoxides

  25. Preparation of Diols Diols formed by reduction of dialdehyde by catalytic hydrogenation as the following reaction.

  26. Mechanism of Reaction

  27. Preparation of Thiols By the reaction of alkyl halide with thiourea to give thiol compound

  28. Reactions of Alcohols 1- Reaction with Hydrogen Halide

  29. 2- Reaction with Thionyl Chloride

  30. 3- Acid Catalyzed Dehydration

  31. 4- Conversion of Alcohols to Ethers By Heating primary alcohols in the presence of Sulfuric acid (Condensation reaction)

  32. 5- Esterification

  33. 6- Oxidation of Alcohols

  34. Primary alcohol is oxidized under strong or mild oxidizing agents to give acid or aldehyde PCC : Pyridinium Chlorochromate

  35. Reaction of Diols Oxidative Cleavage of Vicinal Diols

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