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Chapter 10

Copyright

2010 Pearson Education, Inc.

Organic Chemistry , 7 th EditionL. G. Wade, Jr.

Structure and Synthesis

of Alcohols


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Hydroxyl groups in natural compounds.

Alcohols


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Chapter 10 4

Classification of Alcohols

Primary: carbon with OH is bonded toone other carbon.

Secondary: carbon with OH is bondedto two other carbons.

Tertiary: carbon with OH is bonded to

three other carbons. Aromatic (phenol): OH is bonded to a

benzene ring.


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Chapter 10 5

Examples of Classifications

CH3 C

CH3

CH3

OH*

CH3 CH

OH

CH2CH3*

CH3 CH

CH3

CH2OH

*Primary alcohol Secondary alcohol

Tertiary alcohol


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Chapter 10 6

IUPAC Nomenclature

Find the longest carbon chain containing thecarbon with the OH group.

Drop the - e from the alkane name, add - ol . Number the chain giving the OH group the

lowest number possible.

Number and name all substituents and writethem in alphabetical order.


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Chapter 10 7

Examples of Nomenclature

2-methyl-1-propanol2-methylpropan-1-ol

2-methyl-2-propanol2-methylpropan-2-ol

2-butanolbutan-2-ol

CH3 C

CH3

CH3

OH

CH3 CH

CH3

CH2OH CH3 CH

OH

CH2CH33 2 1 1 2 3 4

2 1


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Chapter 10 8

Alkenols (Enols) Hydroxyl group takes precedence. Assign the

carbon with the OH the lowest number. End the name in ol , but also specify that there is

a double bond by using the ending ene before - ol

4-penten-2-olpent-4-ene-2-ol

CH2 CHCH2CHCH3

OH

5 4 3 2 1


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Chapter 10 9

Naming Priority1. Acids2. Esters3. Aldehydes

4. Ketones5. Alcohols6. Amines7. Alkenes8. Alkynes9. Alkanes10. Ethers11. Halides

Highest ranking

Lowest ranking


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Chapter 10 10

Hydroxy Substituent

When OH is part of a higher priority class ofcompound, it is named as hydroxy.

4-hydroxybutanoic acidalso known as g -hydroxybutyric acid (GHB)

CH2CH2CH2COOH

OHcarboxylic acid

4 3 2 1


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Chapter 10 11

Common Names

Alcohol can be named as alkyl alcohol. Useful only for small alkyl groups.

isobutyl alcohol sec -butyl alcohol

CH3

CH

CH3

CH2OH CH3 CH

OH

CH2CH3


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Chapter 10 12

Naming Diols

Two numbers are needed to locate the twoOH groups.

Use -diol as suffix instead of -ol.

hexane-1,6- diol

1 2 3 4 5 6


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Naturally occurring phenols: a hydroxyl groupdirectly attached to an aromatic ring.

Phenols


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Chapter 10 15

Phenol Nomenclature OH group is assumed to be on carbon 1. For common names of disubstituted phenols,

use ortho- for 1,2; meta- for 1,3; and para- for

1,4. Methyl phenols are cresols.

3-chlorophenol(meta- chlorophenol)

4-methylphenol(para- cresol)

OH

Cl

OH

H 3 C


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Chapter 10 16

Give the systematic (IUPAC) name for the following alcohol.

The longest chain contains six carbon atoms, but it does not contain the carbon bonded to the hydroxylgroup. The longest chain containing the carbon bonded to the OH group is the one outlined by thegreen box, containing five carbon atoms. This chain is numbered from right to left in order to give thehydroxyl-bearing carbon atom the lowest possible number.

The correct name for this compound is 3-(iodomethyl)-2-isopropylpentan-1-ol.

Solved Problem 1

Solution


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Molecules with large hydrophobic groups are generallyinsoluble in water.

Alcohols with three or less carbons are generally watermiscible.

Alcohols with more than three carbons are not miscible,and their solubility decreases as thesize of the hydrophobic group increases.

Physical Properties of Alcoholsoctanol-water partitioning


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Chapter 10 20

Boiling Points of alcohols

Alcohols have higher boiling points than ethers and

alkanes because alcohols can form hydrogen bonds. The stronger interaction between alcohol moleculeswill require more energy to break them resulting in ahigher boiling point.


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Chapter 10 22

Methanol Wood alcohol Industrial production from synthesis gas Common industrial solvent

Toxic Dose: 100 mL methanol Used as fuel at Indianapolis 500

Fire can be extinguished with waterHigh octane ratingLow emissionsLower energy contentInvisible flame


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Chapter 10 23

Ethanol

Fermentation of sugar and starches ingrains

12 15% alcohol, then yeast cells die Distillation produces hard liquors Azeotrope: 95% ethanol, constant boiling Denatured alcohol used as solvent Gasahol: 10% ethanol in gasoline Toxic dose: 200 mL


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Prentice Hall 2001 Chapter 2 24

Nomenclature of Alcohols

IUPAC name - The OH group is a site ofreactivity (a functional group )

Functional group is denoted by the suffix, ol

CH 3 OH CH 3 CH 2 OH

methanol ethanol


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IUPAC Nomenclature of

Alcohols1. Parent Hydrocarbon is the longest

continuous chain that contains the OH

2. Number the chain in direction that givesfunctional group the lowest number

3. If both a substituent and a functionalgroup are present, the functional groupgets the lower number


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Alcohols4. If the functional group gets the same

number when counted from bothdirections, use direction which gives thesubstituent the lower number

5. If there is more than one substituent, citesubstituents in alphabetical order


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Alcohols System is summarized as [Substituent]

[Parent Hydrocarbon] [Functional Group]


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Chapter 10 29

Condensed StructuralFormula Class of Alcohol Common Name IUPAC Name

CH 3OH methyl alcohol methanol

CH 3CH 2OH primary ethyl alcohol ethanol

CH 3CH 2CH 2OH primary propyl alcohol 1-propanol

(CH 3)2CHOH secondary isopropyl alcohol 2-propanol

CH 3CH 2CH 2CH 2OH primary butyl alcohol 1-butanol

CH 3CH 2CHOHCH 3 secondary s ec -butyl alcohol 2-butanol

(CH 3)2(CH 3)2CHCH 2OH primary isobutyl alcohol 2-methyl-1-propanol

(CH 3)3COH tertiary t e r t -butyl alcohol 2-methyl-2-propanol

secondary cyclohexyl alcohol cyclohexanol

Classification and Nomenclature of Some Alcohols

This table shows that alcohols (in red) have higher boiling points and greater solubility in H O than haloalkanes and alkanes with the same number of carbons It also
http://chemwiki.ucdavis.edu/Organic_Chemistry/Hydrocarbons/Alkanes/Properties_of_Alkanes/Haloalkaneshttp://chemwiki.ucdavis.edu/Organic_Chemistry/Hydrocarbons/Alkanes/Properties_of_Alkanes/Haloalkanes


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Chapter 10 30

Physical Properties of Alchols and Selected Analogous Haloalkanes and Alkanes

Compound IUPAC Name Common Name Melting Poing (oC) Boiling Point (

oC) Solubility in H 2O at

23oC

CH 3OH Methanol Methyl alcohol -97.8 65.0 Infinite

CH 3Cl Chloromethane Methyl chloride -97.7 -24.2 0.74 g/100 mL

CH 4 Methane -182.5 -161.7 3.5 mL (gas)/ 100mL

CH 3CH 2OH Ethanol Ethyl alcohol -114.7 78.5 Infinite

CH 3CH 2Cl Chloroethane Ethyl chloride -136.4 12.3 0.447 g/100 mL

CH 3CH 3 Ethane -183.3 -88.6 4.7 mL (gas)/ 100mL

CH 3CH 2CH 2OH 1-Propanol Propyl alcohol -126.5 97.4 Infinite

CH 3CH 2CH 3 Propane -187.7 -42.1 6.5 mL (gas)/ 100mL

CH 3CH 2CH 2CH 2OH 1-Butanol Butyl alcohol -89.5 117.3 8.0 g/100 mL

CH 3(CH 2)4OH 1-Pentanol Pentyl alcohol -79 138 2.2 g/100 mL

This table shows that alcohols (in red) have higher boiling points and greater solubility in H 2O than haloalkanes and alkanes with the same number of carbons. It alsoshows that the boiling point of alcohols increase with the number of carbon atoms.
http://chemwiki.ucdavis.edu/Organic_Chemistry/Hydrocarbons/Alkanes/Properties_of_Alkanes/Haloalkaneshttp://chemwiki.ucdavis.edu/Organic_Chemistry/Hydrocarbons/Alkanes/Properties_of_Alkanes/Haloalkanes

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