Functional GroupsA functional group is a small group of atoms that lend
characteristic properties to the molecule
Properties of the molecule are dictated by the functional groups; allows for systematic study of organic molecules
Halides: R-Xwhere R is any alkyl group, and X a halogen
CH3Cl - chloromethane
C6H5Cl - chlorobenzene
Synthesis: radical chain reaction between an alkane and a halogen
CH4 + Cl2 CH3Cl + HCl
Cl2 2Cl•
•Cl + CH4 HCl + •CH3
•CH3 + Cl2 CH3Cl + •Cl
Cl
h or heat
h or heat
Alcohols: R-OH hydroxyl functional group
Nomenclature - use the suffix “ol”
CH3-CH2-OH ethanol
CH3-CH2-CH2OH 1-propanol
H3C CH2
CH2 CH2
OH
H3C CH2
CH CH3
H3C C
OH
OH
CH3
CH3
1-butanol (1o alcohol)
2-butanol (2o alcohol)
2-methyl-2-propanol(3o alcohol)
Primary alcohol
Secondary alcohol
Tertiary alcohol
Presence of OH group allows hydrogen bonding
As the C chain becomes longer the OH group becomes less important
Synthesis of alcohols
Hydrolysis of a alkyl halide with a strong base
OH- + CH3Br CH3OH + Br-
Addition across a double bond
CH2=CH2 + H2O CH3CH2OH
Charge distribution in ethanol; red indicates negative charge
300 - 400oC
60 - 70 atm
OH
Phenol (C6H5OH)
weak acid, Ka = 1 x 10-10; stability of the phenolate ion (C6H5O-)
Phenols: hydroxyl group attached directly to an aromatic ring
Oil of thyme
Oil of clove
Ethers: R - O - R
C2H5 - O - C2H5 diethylether
C6H5 - O - C2H5 ethylphenylether
Synthesis:
2 R-OH R - O - R + H2OH2SO4
CH3-CH2-OH
CH3-CH2-OH+
H2SO4
140oCCH3-CH2-O-CH2-CH3 + H2O
H2SO4 180oC
2CH2=CH2 + 2 H2O
Kinetics vs thermodynamics
Aldehydes and Ketones
C
H
R
O
C O
C
R
R
O
carbonyl group
aldehyde
ketone
HCHO: formaldehyde
CH3CHO: acetaldehyde
CH3COCH3: dimethlyketone (acetone)C
H3C
H3C
O
C
H3C
H
O
C
H
H
O
Properties of aldehydes and ketones differ because of the aldehyde H atom
CH3CH2OH CH3CHO
1o alcohol aldehyde
ethanol acetaldehyde
(CH3)2CHOH (CH3)2CO
2o alcohol
2-propanol dimethylketone
O2, catalyst,
high temperatures
O2, catalyst,
high temperatures
almond and cherries
cinnamon
vanilla
Carboxylic acids: -COOH functional groupC
O
OH
HCOOH - formic acid (ant venom)
CH3COOH - acetic acid (vinegar)
Carboxylic acids hydrogen bond - “dimers”
Synthesis
Catalytic oxidation of aldehydes
CH3CHO CH3COOHO2, Mn2+
C
O
OH
H
C
O
OH
H3C
Esters: R-COO- R’C
O
OR
R'
C
O
OH
H3C CH2CH3
OHCH3C
O
OCH2CH3
+ H2O
acetic acid + ethanol ethylacetate
Tristearin: animal fatty acid tri-esters
CH2OHCHOHCH2OH + 3 CH3(CH2)16COOH
glycerol stearic acid
Fats (solids) and oils (liquids) are triesters formed from glycerol and three carboxylic acids (fatty acids)
Saturated - C-C single bonds
Unsaturated - one (mono-unsaturated) or more (polyunsaturated) C=C bonds
Amines:
NH
HR
NH
R'R
NR
R'R"
NH
HH ammonia
primary amine (1o)
secondary amine (2o)
tertiary amine (3o)
CH3NH2 methylamine
(CH3)2NH dimethylamine
(CH3)3N trimethylamine
C6H5NH2 aniline
Amines are bases:
NicH2+(aq) + 2 NH3(aq)
Nic(aq) + 2 NH4+(aq)
Synthesis of amines
a) Naturally occurring
b) NH3 + CH3Cl CH3NH2 + HCl
NH2
nicotineN
N
CH3
Amino acids: carboxylic acid containing an amine group
Glycine: NH2CH2COOH
H3NCHCOOH+
R
H3NCHCOO+ -
R
H2NCHCOO-
R
- H3O+ - H3O+
+ H3O++ H3O+
cationic form
predominant in acidic solutions
anionic form
predominant in basic solutions
dipolar form - zwitterion
Amides: -CONH2- group
Formed by reaction between NH3 or 1o or 2o amine and acid
CR' N
O
H
R
CH3C
O
O
H NHH
CH2CH3 CH3C
O
NHCH2CH3
+ H2O
C
O
HOCH2
N
H
H
+ C
O
HOCH2
NH2 C
O
HOCH2
NH
C
O
CH2
NH2
+ H2O
Proteins: polypeptides with CONH linkage between amino acids
glycine + glycine diglycine + H2O
http://www.cryst.bbk.ac.uk/pps97/course/section3/helix.pdb
