All Classes of Organic Compounds Functionalized...

Alcohols Phenols Ethers Thiols Dissulfides Amines

-O- -S- -N-

OC

Alkanes Alkenes Alkynes Aromatics

Aldehydes Ketones Acids Esters Anhydrides Amides

OC-N

OC-O

Hydrocarbons

All Classes of Organic Compounds

Functionalized Hydrocarbons

Halides

F,Cl,Br O,S,N

Alcohols, Ethers, Phenols

Structure of Functional Groups


Structure of Functional GroupsThe oxygen atom in alcohols, phenols, and ethers is sp3

hybridized. Two of the sp3 orbitals are involved in bonding to hydrogen or carbon, and the remaining two contain lone-pair,

or non-bonding, electrons.

H

O

H R

O

H R

O

R’

water alcohol ether


Structure of Functional Groups

In water, the H-O-H bond angle is 104.5° due to repulsion of the bonding electron pairs by the larger non-bonding electron pairs.

In alcohols, phenols, and ethers the corresponding bond angles are closer to the expected tetrahedral 109.5° due to the replacement of one or both hydrogen atoms by larger carbon atoms.

Common Names of Alcohols

Isomerism in Alcohols

1-propanol 2-propanol

Subclassification of Alcohols

Nomenclature of Alcohols

closest to the

Nomenclature of Alcohols

Physical Properties of AlcoholsBoiling points increase with molecular weight

and decrease with branching.

Boiling points are higher than alkanes of similar molecular weight.

H3CCH2

H2C

CH2H2C

CH2H2C

CH3

H3CCH2

H2C

CH2H2C

CH2H2C

CH3

H3CCH2

H2C

CH2H2C

CH2H2C

CH3

H3CCH2

H2C

CH2H2C

CH2H2C

CH3

H3CCH2

H2C

CH2H2C

CH2H2C

CH3

Octane, boiling point = 126 °C

Attractive forces between alkane molecules are limited to simple London forces.

H3CCH2

H2C

CH2H2C

CH2H2C

O

H3CCH2

H2C

CH2H2C

CH2H2C

O

H3CCH2

H2C

CH2H2C

CH2H2C

O

H3CCH2

H2C

CH2H2C

CH2H2C

O

H3CCH2

H2C

CH2H2C

CH2H2C

OH H H HH

Heptanol, boiling point = 176 °C

Attractive forces between alcohol molecules include both dispersion forces and relatively strong hydrogen bonding.

Physical Properties of Alcohols-Solubility

Alcohols are more water soluble than alkanes, but their water solubility is limited by the size of the

nonpolar portion of the molecule.

CH3O

H

H3CCH2

CH2CH2

CH2CH2

CH2O

H

Nonpolar, or hydrophobic portions

of moleculesPolar, or hydrophilic portions of molecules

Physical Properties of Alcohols-Solubility

CH3

OH

CH3

OH

HO

H

THE RELATIVELY SMALL ATTRACTION BETWEENMETHANOL MOLECULES MAKES IT EASY FORWATER TO SEPARATE INDIVIDUAL METHANOL

MOLECULES FROM EACH OTHER AND DISSOLVE THE ALCOHOL.

METHANOL IS VERY SOLUBLE IN WATER.

H3CCH2

CH2CH2

CH2

CH2CH2

OH

H3CCH2

CH2CH2

CH2

CH2CH2

OH

HO

H

THE RELATIVELY LARGE ATTRACTION BETWEEN

HEPTANOL MOLECULES MAKES IT DIFFICULT FOR

WATER TO SEPARATE INDIVIDUAL HEPTANOL

MOLECULES FROM EACH OTHER AND DISSOLVE THE ALCOHOL. HEPTANOL IS VERY SLIGHTLY

SOLUBLE IN WATER.

usually requires anacid catalyst, indicated by “H+”

Chemical Properties of Alcohols

Intramolecular Dehydration Reactions

C C

OH H

C C + H2O

ALCOHOL ALKENE

“H” and “OH”on adjacent carbons

?


Intramolecular Dehydration Reactions-Specific Examples

H C C

H

OH

H

H

H

H+ HC C

H

H

H

+ H2O

Ethanol EtheneH+

C2H6O C2H4H+

+ H2O

+ H2O


Intramolecular Dehydration Reactions-Specific Examples

H C C

H

OH

H

C

H

H

H

HH+

HC C

H

H

C

+ H2OH

HH

1-propanol, C3H8O 1-propene, C3H6

H C C

H

H

C

C

OH

H

H

HH

HH

H+

2-methyl-2-propanol, C4H10O 2-methyl-”1”-propene, C4H8

HC C

H

C

C H

HH

HH

H + H2O

Does it make any difference which H is removed??

OH leaves


Intramolecular Dehydration Reactions-Zaitsev’s Rule

+ H2OH C C

H

H

H

OH

CH+

H

H

C

H

H

H

C4H8

C4H10O2-butanol,

HC C

H

H

C H

CH H

HH

CC C

H

H

C H

HH

HH

H

If isomeric alkenes are possible products from an alcohol dehydration, the HYDROGEN atom is lost from the carbon

with the least number of hydrogens attached.

MAJOR PRODUCTMINOR PRODUCT


Intermolecular Dehydration Reactions

H C C

H

H

H

O

H

H+H O C C

H

H

H

H

H

H+ + H2OH C C

H

H

H

O

H

C

H

H

C

H

H

H

C2H6O C2H6O C4H10O H2O

“H” and “OH”on two different

molecules Also called “condensation” or “dehydration synthesis”-

an extremely important reaction in biochemistry.

+ +

The reaction is run under different conditions than the

“intramolecular” dehydration.

Chemical Properties of AlcoholsOxidation (or Dehydrogenation) Reactions

ALCOHOLALDEHYDE

or KETONE

C

O

H

H

C

O[O] H

H

Two hydrogen atoms are lost and a double bond forms between the carbon and oxygen atoms.

C

O


Oxidation of Primary Alcohols Yields Aldehydes

[O]H C C O

H

H

H

H

H H C COH

H H

[O]C C C O

H

H

H

H

H C C COH

H H

H

H

H

H

H

H

[O]C C C O

H

H

H

H

H C C COH

H H

H

H

CH

C

H

H

H

H

H

H

H

Ethanol, C2H6O Ethanal (acetaldehyde), C2H4O

1-Propanol, C3H8O Propanal (propionaldehyde), C3H6O

1-Butanol, C4H10O Butanal (butyraldehyde), C4H8O


Oxidation of Secondary Alcohols Yields Ketones

[O]C C C C

H

O

H

H

H

H

H

H

[O]C C C C

H

O

H

H

H

H

H

C

H

H

HH

H

H

C C C C

O

H

H

H

H

H

C

H

H

H

H

H

H

H

H

C C C C

O

H

H

H

H

H

H

H

H

2-butanol, C4H10O 2-butanone, C4H8O

3-pentanol, C5H12O 3-pentanone, C5H10O


Tertiary Alcohols Do Not Easily Oxidize

[O]H C C O

H

H

C

C

H

H H H

H H H

N.R.No Reaction


Oxidation (Some Details)

Oxidation of primary alcohol actually proceeds in two steps from alcohol to aldehyde to carboxylic acid.

R C O HH

HR C O H

OR C

OH

primary alcohol aldehyde carboxylic acid


Oxidation (Some Details)

For the simple primary alcohol ethanol CH3CH2OH, the complete chemical equation (with dichromate as the reagent)

can be written.

3 CH3CH2OH 2 Cr2O72- 16 H+

3 CH3COOH 11 H2O 4 Cr3+

+ +

+ +

Cr6+ Cr3+

A color change is characteristic of the reaction of dichromate with ethanol.

ethanol

aceticacid


An Application of the Oxidation Reaction

Phenols, Ethers, and

Organic Sulfur Compound

Phenols - Structure

General Structure - A “hydroxy” (OH) group attached directly to an aromatic ring:

OH OH

Phenol β-Naphtholα-Naphthol

OH

CH2 OH

Note:is not a phenol.

Phenols - Nomenclature

OH

ClBr

OH

NO2

OH

Cl

OH

Br

Br

OH

CH32-nitrophenol

orortho-nitrophenol

3-chlorophenolor

meta-chlorophenol

4-methylphenolor

para-methylphenol

2,4-dibromophenol

4-bromo-2-chloro-5-isopropyl-phenol

Phenols are named as aromatic compounds, using the ortho-, meta-, and para- prefixes or appropriate numbering.

1 1

1

1

2

1

Phenols - Physical Properties

Low Melting SolidsSoluble in Nonpolar SolventsAlso, Quite soluble in Water

OH OH

OH

OH

OH

Name Phenol Catechol Resorcinol

M.P. 40.5 ºC 105 ºC 110 ºC

Solubility 8.3 g/100mL 43 g/100mL 110 g/100mL in water

Phenols - Acidity

In water, phenol dissociates slightly as a weak acid. (Another name for phenol itself is “carbolic acid”)

OH O

+ H2O + H3O +

_

Acid Base Base Acid

Phenols - Acidity

How acidic is Phenol?pKa = A general measure of acidity.

The lower the pKa, the stronger the acid.

! ! Compound pKa

Methanol 16 Water 15.7 Phenol 9.9 Acetic Acid 4.8

Phosphoric Acid -2.1 Hydrochloric Acid -7

nonacids

weak acids

strong acids

Phenols - Chemical Properties

OH

OH

O

O

+ 2 H .

OXIDATION

REDUCTION

O-Na+OH

+ NaOH + HOH

Acid-BaseReactions

Phenol Sodium phenoxide

Hydroquinone Paraquinone

Oxidation-ReductionReactions

Phenols - Examples of Important Compounds

o-phenyl phenol n-hexylresorcinol

butylated hydroxy anisole(BHA)

butylated hydroxy toluene(BHT)

OH

OH

OCH3

OH

OH

CH2CH2CH2CH2CH2CH3

OH

CH3

Structure of Ethers


Intermolecular Dehydration Reactions

H C C

H

H

H

O

H

H+H O C C

H

H

H

H

H

H+ + H2OH C C

H

H

H

O

H

C

H

H

C

H

H

H

C2H6O C2H6O C4H10O H2O

“H” and “OH”on two different

molecules Also called “condensation” or “dehydration synthesis”-

an extremely important reaction in biochemistry.

+ +

The reaction is run under different conditions than the

“intramolecular” dehydration.

diethyl ether2 molecules of ethanol

Nomenclature of Ethers

Common NomenclatureFor simple carbon groups, the two groups attached to the ether

oxygen are named as alkyl groups and “ether” is added to the name.

H3CCH2

OCH3

H3CCH2

OCH2

CH3

H3CCH2

O

ethyl methyl ether diethyl ether

ethyl phenyl ether

Nomenclature of Ethers

IUPAC System

Shorter carbon chains are named as “alkoxy-” groups.

CH3CH2

CHCH2

CH2Cl

OCH3

H3CCH2

O

Br

F

1-chloro-3-methoxypentane 2-bromo-4-ethoxy-1-fluorobenzene

Important Anaesthetics

Physical Properties of EthersPhysical Properties of Ethers

Boiling points of ethers increase with molecular weight and decrease with increased branching

Physical Properties of Ethers

Attractive forces between ether molecules include only dispersion forces making their boiling points similar to alkanes of similar molecular weight.

H3CCH2

H2C

CH2H2C

CH3

H3CCH2

H2C

CH2H2C

CH3

H3CCH2

H2C

CH2H2C

CH3

H3CCH2

H2C

CH2H2C

CH3

H3CCH2

H2C

CH2H2C

CH3

Hexane, boiling point 69 °C

H3CCH2

H2C

CH2O

CH3

H3CCH2

H2C

CH2O

CH3

H3CCH2

H2C

CH2O

CH3

H3CCH2

H2C

CH2O

CH3

H3CCH2

H2C

CH2O

CH3

Butyl methyl ether, boiling point 71 °C

H3C

CH2H2C

CH2H2C

O

H3C

CH2H2C

CH2H2C

O

H3C

CH2H2C

CH2H2C

O

H3C

CH2H2C

CH2H2C

O

H3C

CH2H2C

CH2H2C

OH H H HH

1-Pentanol, boiling point 138 °C

Physical Properties of EthersThe solubility of a compound in water is related to the ability of water molecules

to overcome the attractive forces between two potential solute molecules.

H3CCH2

CH2CH2

CH2CH3

H3CCH2

CH2CH2

CH2CH3

HO

H

Hexane,insoluble

in water

1-pentanol,slightly soluble

in water

HO

H

H3CCH2

CH2CH2

CH2OH

H3CCH2

CH2CH2

CH2OH

HO

H

Physical Properties of EthersThe ether oxygen can hydrogen bond with water.

The result is some water solubility.

HO

H

HO

H

HO

H

1-methoxybutane,slightly soluble

in water

1,2-dimethoxyethane,very soluble

in water

H3CCH2

CH2CH2

OCH3

H3CCH2

CH2CH2

OCH3

H3CO

CH2CH2

OCH3

H3CO

CH2CH2

OCH3

HO

H

HO

H

HO

H

As a general rule, one polar atom (O,N) can “solubilize” four to six

carbon atoms.

Organic Sulfur CompoundsStructures

R-S-H Thiols (Mercaptans)

R-S-R Thioethers (Sulfides)

R-S-S-R (Disulfides)

Nomenclature

CH3-S-H Methyl Mercaptan (Methanethiol)

CH3-S-CH3 Dimethyl Sulfide (Dimethyl Thioether)

Physical Properties

Distinct odors and flavors

Lower boiling points than alcohols (Why?)

Weak Acids: Phenols > Thiols > Alcohols

Thiols are easily “oxidized” to Disulfides.

2 R-SH --------------------> R-S-S-R

This reaction takes place within large protein structures:

Organic Sulfur CompoundsChemical Properties

H-SS-H

SS

Oxidation

Reduction

[O]

Mercaptans = “Mercury capturing”

R-SH R-S

Hg2+ Hg + 2 H+

R-SH R-S

Process is called “chelation”

Organic Sulfur CompoundsChemical Properties

Where Do We Find Thiols ??

Where Do We Find Disulfides ??

All Classes of Organic Compounds Functionalized...

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