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Organic Chemistry II CHEM 271. Chapter One Alcohols, Diols and Thiols.

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Presentation on theme: "Organic Chemistry II CHEM 271. Chapter One Alcohols, Diols and Thiols."— Presentation transcript:

1 Organic Chemistry II CHEM 271

2 Chapter One Alcohols, Diols and Thiols

3 Nomenclature of Alcohols

4 Functional Class Nomenclature of Alcohols( Common Names) Name the alkyl group and add "alcohol" as a separate word. 4 CH 3 CH 2 OH CH 3 CH 2 OH CH 3 CHCH 2 CH 2 CH 2 CH 3 CH 3 CHCH 2 CH 2 CH 2 CH 3OH CH 3 CCH 2 CH 2 CH 3 OH CH 3 Ethyl alcohol Ethyl alcohol 1-Methylpentyl alcohol 1-Methylpentyl alcohol 1,1-Dimethylbutyl alcohol

5 IUPAC Nomenclature of Alcohols Name as "alkanols." Replace –e ending of alkane name by -ol. Number chain in direction that gives lowest number to the carbon that bears the —OH group. CH 3 CH 2 OH CH 3 CHCH 2 CH 2 CH 2 CH 3 OH CH 3 CCH 2 CH 2 CH 3 OH CH 3 Ethanol Ethanol 2-Hexanol 2-Hexanol 2-Methyl-2-pentanol

6 Name these: 6 2-methyl-1-propanol 2-methyl-2-propanol 2-butanol 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 7 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 108

9 Hydroxy Substituent When -OH is part of a higher priority class of compound, it is named as hydroxy. Example: 9 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 => 10


12 12 =>

13 Diols Two numbers are needed to locate the two -OH groups. Use -diol as suffix instead of -ol. Chapter 1013 1,6-hexanediol =>

14 Glycols 1, 2 diols (vicinal diols) are called glycols. Common names for glycols use the name of the alkene from which they were made. 14 1,2-ethanediol ethylene glycol 1,2-propanediol propylene glycol =>

15 Glycrol 1, 2,3 Triols are called glycrol>

16 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 CH 3 ─ S ─ HCH 3 ─ CH 2 ─ S ─ H


18 Physical Properties of Alcohols 1.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. 4.As the molecular weight increase, solubility in water decrease. 5.The solubility of alcohols in water is due to hydrogen bonding between alcohol and water molecules. 6. They are weak acids (weaker than Phenol).

19 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:

20 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:

21 Acidity of Alcohols pK a 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 1021

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

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


25 Preparation of Alcohols by Reduction of Aldehydes and Ketone




29 Preparation of Alcohols by reduction of Carboxylic acids and Esters


31 Preparation of Alcohols from Epoxides


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


35 Mechanism of Reaction

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

37 1- Reaction with Hydrogen Halide Reactions of Alcohols

38 2- Reaction with Thionyl Chloride

39 3- Acid Catalyzed Dehydration

40 4- Conversion of Alcohols to Ethers By Heating primary alcohols in the presence of Sulfuric acid (Condensation reaction)


42 5- Esterification



45 6- Oxidation of Alcohols

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



49 Oxidative Cleavage of Vicinal Diols Reaction of Diols


51 Reactions of Thiols Thiols are weak acids but more acidic than alcohols.

52 2- Oxidation of Thiols

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