Alcohols, Phenols, Thiols, and Ethers

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Alcohols, Phenols, Thiols, and Ethers

• Chapter 13

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Introduction

• Alcohol organic compound that contains a
  hydroxyl (-OH) group attached to an alkyl group
• Phenol organic compound that contains a
  hydroxyl (-OH) group attached to an aryl group
• Ether organic compound that has two alkyl or
  aryl groups attached to the oxygen atom can be
  thought of as a substituted alcohol.

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Examples

• Alcohols -OH hydroxyl CH3-OH
• CH3CH2-OH
• Phenols
• Ethers -O- CH3-O-CH3

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Practice Problem 1

• Classify each as an alcohol (1), phenol (2), or
  an ether (3)
• A. _____ CH3CH2-O-CH3 C. _____ CH3CH2OH
• B. _____

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Solution 1

• Classify each as an alcohol (1), phenol (2), or
  an ether (3)
• A. ____ CH3CH2-O-CH3 C. ____ CH3CH2OH
• B. _ __

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Structure and Properties

• R-O-H portion of alcohol is similar to the
  structure of water.
• The oxygen and two atoms bonded to it lie in the
  same plane.
• The bond angle is 104
• Hydroxyl groups are very polar because of
  significantly different electronegativities.
• Hydrogen bonding can form between alcohol
  molecules.

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Hydrogen Bonding
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Results of Hydrogen Bonding

• Alcohols boil at much higher temperatures than
  hydrocarbons of similar molecular weight.
• Alcohols with fewer than five carbons are very
  soluble in water.
• Alcohols with five to eight carbons are
  moderately soluble in water.
• As the nonpolar (R) portion of the alcohol gets
  larger, the water solubility decreases.

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Solubility of Alcohols

• Very large alcohols are not soluble in water.
• Hydrophobic water fearing used to describe
  nonpolar region of molecule
• Hydrophilic water loving used to describe
  polar region of molecule
• CH3CH2CH2CH2CH2CH2CH2CH2CH2OH

Hydrophobic
Hydrophilic
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Solubility of Alcohols

• An increase in the number of hydroxyl groups will
  increase the influence of the polar hydroxyl
  group.
• Diols and triols are more water soluble than
  alcohols with only a single hydroxyl group.

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Practice Problem 2

• Circle the more soluble alcohol in each pair.

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Solution 2

• Circle the more soluble alcohol in each pair.

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Nomenclature of Alcohols

• A carbon compound that contain -OH (hydroxyl)
  group
• In IUPAC name, the -e in alkane name is replaced
  with -ol.
• CH4 methane
• CH3OH methanol (methyl alcohol)
• CH3CH3 ethane
• CH3CH2OH ethanol (ethyl alcohol)

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More Names of Alcohols

• IUPAC names for longer chains number the chain
  from the end nearest the -OH group.
• CH3CH2CH2OH
• OH
• CH3CHCH3
• CH3 OH
• CH3CHCH2CH2CHCH3

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Alcohols that contain more than one hydroxyl group

• Alcohols containing two hydroxyl groups are named
  diols.
• Alcohols containing three hydroxyl groups are
  named triols.
• A number giving the position of each of the
  hydroxyl groups is needed in these cases.

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Practice Problem 3

• Name the following alcohols
• A. OH
• CH3CHCHCH2CH3
• CH3
• OH
• B.

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Solution 3

• Name the following alcohols
• A. OH
• CH3CHCHCH2CH3
• CH3
• OH
• B.

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Homework

• Pages 379-380 13.11-13.14
• Page 360 13.1 13.2
• Due Tomorrow!!!!

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Section 13.3

• It is your responsibility to read over section
  13.3 Medically Important Alcohols (pgs.
  360-361) and take notes on the material covered!
• It will be on the weekly quiz and the test!

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Classification of Alcohols

• Alcohols can be classified as primary (1),
  secondary (2), or tertiary (3) depending on the
  number of alkyl groups attached to the carbon
  bearing the OH group.

Methanol 1 alcohol 2 alcohol
3 alcohol
ethanol 2-propanol
2-methyl-2-propanol
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Practice Problem 4

• Classify each of the following alcohols as
  primary, secondary, tertiary, or aromatic.
• 1-butanol
• 3-pentanol
• 1-methylcyclopentanol
• 2-methyl-2-pentanol

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Solution 4

• 1-butanol
• 3-pentanol
• 1-methylcyclopentanol
• 2-methyl-2-pentanol

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Homework

• Pages 380-381 13.15, 13.16, 13.18, 13.19, 13.20,
  13.21, 13.22, 13.27, and 13.28
• Due Tomorrow!

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Preparation of Alcohols

• REVIEW Hydration an addition reaction in
  which a water molecule is added to an alkene
  requires acid as catalyst

Alkene Water Alcohol

• Markovnikovs rule applies!!

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Preparation of Alcohols

• Hydrogenation of aldehydes and ketones

In an aldehyde, R1 and R2 may be either alkyl
groups or H. In a ketone, R1 and R2 are both
alkyl groups. We will discuss this in more
detail in section 14.4.
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Dehydration of Alcohols

• Alcohols undergo dehydration (lose water) when
  heating with concentrated sulfuric or phosphoric
  acid.
• Dehydration is an example of an elimination
  reaction.
• Elimination reaction a reaction in which a
  molecule loses atoms or ions from its structure.
• Dehydration is opposite of hydration!

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Dehydration of Alcohols

• Zaitsevs rule in an elimination reaction, the
  alkene with the greatest number of alkyl groups
  on the double bonded carbon (more highly
  substituted alkene) is the major product of the
  reaction

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Phenols

• Phenols compounds in which the hydroxyl group
  is attached to a benzene ring
• They are polar compounds because of the polar
  hydroxyl group.
• Smaller phenols are somewhat soluble in water.
• They are found in fragrances and flavorings and
  are also used as preservatives and germicides.

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Common Phenols and their Uses
Thymol (mint)
CH3
(CH3)2HC
Carvacrol (savory)
OH
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Common Phenols and their Uses
Butylated hydroxytoluene, BHT(Food preservative)
Phenol (Carbolic acid when dissolved in
water) Antiseptic and disinfectant used by
Joseph Lister to bathe wounds and sterlize
instruments
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Ethers
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Ethers

• What are they?
• How are they used?
• What do you know about them?

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Structure of Ethers

• Similar structure to alcohols
• Alcohols R-OH
• OH is hydroxy group
• Ethers R-OR
• OR is alkoxy group

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Alkoxy group

• R groups can be the same
• CH3-O-CH3
• Both R groups have one carbon

• R groups can be different
• CH3CH2CH2-O-CH3
• One R group has three carbons while the other
  has one

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Alkoxy group

• The root names are used with oxy to name that
  portion of the ether
• meth- -oxy
• eth- -oxy
• prop- -oxy

methoxy
ethoxy
propoxy
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Naming ethers IUPAC Way

• Find the root name of the smaller R group
  Ex meth-, eth-, prop-
• Add oxy
• Ex methoxy, ethoxy, propoxy
• Add the full name of the larger R group
• EXAMPLE

methoxypropane
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Name that ether
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Draw the structure of

• 1. methoxypropane
• 2. methoxyoctane
• 3. propoxypropane
• 4. ethoxypentane

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Naming Ethers Common Name

• Name by placing the names of the two alkyl groups
  attached to the ether oxygen as words in front of
  the word ether. Typically this is done in
  alphabetical order.

Diethyl Ether
Ethyl methyl ether
Butyl propyl ether
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Properties of ethers

• The C-O bond in ethers is polar, making the
  molecule polar
• Ethers have very low boiling points
• Ethers are relatively inert, but flammable in air

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Lets compare

• Ether
• CH3 O-CH2CH3
• Molecular Formula
• C3H8O
• Molecular Weight
• 60.09g/mol
• Boiling Point
• 7.9C

• Alcohol
• CH3CH2CH2-OH
• Molecular Formula
• C3H8O
• Molecular Weight
• 60.09g/mol
• Boiling Point
• 97.2C

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Preparing ethers

• Ethers are formed from alcohols
• R-OH R-OH ? R-O-R H2O
• R and R can be the same or different
• Called a dehydration reaction

H
?
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Predict the products
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Common uses

• Ethers as anesthetics
• Penthrane
• Enthrane
• Ethers as additives in gasoline
• MTBE methyl tert-butyl ether

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Thiols

• Compounds that contain the sulfhydryl group
  (-SH)
• Similar to alcohols in structure, but the sulfur
  atom replaces the oxygen atom
• Have nauseating aromas defense spray of North
  American striped skunk

Trans-2-butene-1-thiol
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Naming Thiols

• Use the same rules as for alcohols except that
  the full name of the alkane is retained.
• Add the suffix thiol.

ethanethiol
3-methyl-1-butanethiol
1,2-ethanedithiol
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Uses of Thiols

• Thiols are involved in protein structure and
  conformation.
• Cysteine is an amino acid that contains a
  sulfhydryl group.
• BAL (British Anti-Lewisite) is used as an
  antidote for mercury poisoning.
• Coenzyme A serves as a carrier of acetyl groups
  in biochemical reactions.

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Homework

• Pg. 381-382 13.43, 13.44, 13.45, 13.48, 13.49,
  13.51, 13.52, 13.53, 13.59, 13.60