Tutorial #20 - Organic Chemistry
1. Nomenclature
Find the longest chain of carbons
Name the hydrocarbon, using –ane, -ene or –yne as required
Identify any substituent groups on the chain
Number the chain appropriately.
e.g. CH3-CH2-CH2-CHCl-CH3
5 carbons, i.e. pent - something
no double or triple bonds, thus pentane
a chlorine on one of the C’s, thus chloropentane
numbering from the right to obtain the lowest number, 2-chloropentane
e.g.
H2C
H
C
CH3
Cl
Cl
a. 4 carbons, i.e. but – something
b. a double bond, i.e. butene
c. the double bond is on carbon number 1, thus 1-butene
d. two chlorines on the C, thus dichlorobutene
e. numbering from the left, 3,3-dichloro-1-butene
e.g. CHC-CH2-C6H5, where the C6H5 is a phenyl group
HC
HC
C
H2
H
C
C
H
CH
CH
a. The ring does not enter into the longest "chain", and so this is a three carbon chain, i.e.
prop - something.
b. a triple bond, thus 1-propyne.
c. a phenyl group, thus phenyl-1-propyne
d. phenyl on the third carbon, thus 3-phenyl-1-propyne
You could also name this as a benzene compound, i.e. propynyl benzene, where the
propynyl indicates a propyne group as a substituent. Since the C in the propynyl group
must the number 1 (since it is bound to the benzene), the correct name would be
2-propynyl benzene.
e.g. CH3-CH2-CHOH-CH2-CH2-CH3
H2
H2
C H C
CH3
H3C
C
C
H2
OH
a. an alcohol, 6 carbons, i.e. derived from hexane, thus hexanol
3. the OH group is on the third carbon, thus 3-hexanol, or hexan-3-ol
e.g. CH3-CH2-CH2NH2
H3C
H2
C
C
H2
NH2
a propane, i.e. 1-aminopropane, or an amine, i.e. propylamine
e.g. CH3-CH2-CH2-CH2-COOH
H3C
H2
C
C
H2
H2
C
O
OH
a carboxylic acid, 5 carbons, pentane carboxylic acid
e.g. C6H5 – CH2 – COOH
HO
HC
O
H
C
CH2
HC
CH
C
H
a carboxylic acid, 2 carbons, phenylacetic acid
e.g. H-CO-C3H7
O
C
H
H2
C
C
H2
CH3
recognize the carbonyl group, CO, and the fact that the C in the CO group is a primary
carbon, i.e. bound to only one other carbon. This must therefore be an aldehyde. It has
four carbons, and is therefore derived from butane, butyl aldehyde
e.g. CH3-CO-C2H5
O
C
H2
H3C
CH3
recognize the carbonyl group, CO, and the fact that the C in the CO group is a secondary
carbon, i.e. bound to two other carbons. This must therefore be a ketone, methyl ethyl
ketone.
e.g. CH3 – CO – O – C4H9
O
H3C
O
H2
C
C
H2
H2
C
CH3
This is an ester, (note the COO-C linkage), butyl methyl ester. Note that we name the
group on the oxygen first (the butyl group in this case)
Note also that this ester contains the very common H3C-COO group, commonly called
the acetyl group. Since the acetyl group is in an ester, it is called an acetate, or butyl
acetate in this case.
e.g. NH2CH3
methyl amine or amino methane
e.g. CH3 – CO – NH2
O
H3C
NH2
an amide, (note the C-O-N), ethanamide. Since this also contains the common acetyl
group, acetamide is its more common name.
CH3 – CO – NHCH3
an amide, (note the C-O-N), N-methyl acetamide, denoting the fact that the methyl group
is on the N atom.
Cl
Cl
dichlorobenzene. Since the chlorine atoms are on opposite carbons, paradichlorobenzene,
or 1,4-dichlorobenzene.
Cl
NO2
Cl
2,5-dichloronitrobenzene (since we named it as a nitrobenzene, carbon number one is the
one bound to the nitro group)
OH
O
Cl
parachlorobenzoic acid or 4-chlorobenzoic acid (since we named it as a benzoic acid, the
COOH group is on carbon number 1)
2. Reactions
Reactions you should know:
Alkanes:
Reaction with oxygen, chlorine, dehydrogenation
Alkenes:
addition reactions
Alkynes:
addition reactions
Alcohols:
dehydration, formation of ethers
Aldehydes:
formation from primary alcohols
Ketones:
formation from secondary alcohols
Carboxylic acids: + alcohol = ester
+ amine = amide
Esters:
formation from acids
Amides:
formation from amines, acids
(1) Alkanes
C2H6 + O2 oxidation of alkanes by oxygen results in CO2 and water, generally
thus, C2H6 + 5 O2 2 CO2 + 3 H2O
C2H6 + Cl2 chlorination of alkanes results in substitution of Cl for H:
e.g. C2H6 + Cl2 C2H5Cl + HCl
C2H5Cl + Cl2 C2H4Cl2 + HCl
and so on...
dehydrogenation results in the production of a double bond. The most important example
is the dehydrogenation of ethane to produce ethylene:
C2H6 H2C=CH2 + H2 (requires a catalyst and high temperatures)
(2) Alkenes, Alkynes
The important thing here is the double or triple bond. Rich in electrons, chemistry will
generally take place at this bond. Addition reactions add something across the double
bond:
e.g. H2C=CH-CH3 + H2 H3C-CH2-CH3 (i.e. hydrogenation)
e.g. H2C=CH-CH3 + Cl2 HClC-CHCl-CH3
e.g. H2C=CH-CH3 + H2O H3C-CHOH-CH3 (i.e. production of an alcohol, needs a
catalyst)
(3) Alcohols
e.g. butanol + methanol ? (in the presence of sulfuric acid and heat)
Alcohols react with one another to form ethers. In this case, three ethers are possible:
C4H9OH + HOC4H9 C4H9 - O - C4H9 (dibutyl ether)
C4H9OH + HOCH3 C4H9 - O - CH3 (methylbutyl ether)
CH3OH + HOCH3 CH3 - O - CH3 (dimethyl ether)
(4) Aldehydes
Formed from PRIMARY alcohols, i.e. alcohols in which the C bound to the -OH group is
itself bound to only one other carbon.
e.g. CH3CH2CH2OH CH3CH2HC=O (propanol propanal, requires an oxidative
environment, often accomplished through metabolism in an organism)
(5) Ketones
Formed from SECONDARY alcohols, i.e. alcohols in which the C bound to the -OH
group is itself bound to two other carbons.
O
OH
Oxidation
or 3-pentanone or diethylketone
(6) Carboxylic Acids
Carboxylic acid + Alcohol Ester + Water (in the presence of heat and H2SO4)
e.g. acetic acid + methanol methyl acetate + water
CH3COOH + HOCH3 CH3COOCH3 + H2O
e.g. pentanoic acid + propanol propyl pentanoate + water
C4H9COOH + HOCH2CH2CH3 C4H9COOCH2CH2CH3 + H2O
Carboxylic Acid + Amine Amide + water
e.g. acetic acid + ethylamine ethylacetamide + water
CH3COOH + C2H5NH2 CH3CONHC2H5 + H2O
e.g. hexanoic acid + benzylamine benzylhexamide + water
C5H11COOH + C6H5NH2 C5H11CONHC6H5
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