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Nomenclature of organic compounds Dr. M. Abd- Elhakeem Faculty of Biotechnology Organic Chemistry Chapter 2
Nomenclature of organic compounds
Dr. M. Abd-Elhakeem
Faculty of Biotechnology
Organic Chemistry
Chapter 2
The nomenclature of organic molecules started with common or traditional name depending mainly on the origin in the history of the science or the natural sources of the compound.
But the relationship of these names to each other is arbitrary, and no rational or systematic principles.
Common names
NH2 OHCOOH
CH3
CH3
CH3O
Aniline PhenolBenzoic acid
Xylene Acetophenone Naphthalene
CH3 OCH3
Toluene Anisole
CH3
OH
O
CH3
CH3
O
CH CH
acetic acid
Acetone
Acetylene
CH3
H
O
CH3 OH
CH3
OH
H
H
O
acetaldehyde
formaldehyde
methanol
ethanol
The IUPAC nomenclature of organic chemistry is a systematic method of naming organic chemical compounds as recommended by the International Union of Pure and Applied Chemistry (IUPAC).
every possible organic compound should have a name according to a number of rules
IUPAC System for Nomenclature
Rules for Nomenclature
1- The name of organic molecule is divided in to two parts
Number of carbon atom
Function group
FUNCTIONAL GROUP – atom or group of atoms which gives an organic compound its characteristic chemical properties.
Second part First part Function group No of carbon
atoms
Alkane ane Alkene ene Alkyne yne Alcohol anol Aldehyde anal Ketone anone Acid anoic Substitution yl
1. meth2. eth3.prop4. but5. pent6.hex7.hept8. oct9. non10. decIn case of
cyclic form add firstly cyclo-
CH2
CH3
CH3
OH
CH3
COOH
propanoic acid
Propene Propanol
CH3
CH3 OCH3
CH3
CH3
CH3OH
3-pentanone 2-pentyne 2-butanol
2- Put the lowest number that indicate the position of function group.
3- In case of branched chain (this means there is one principle chain or parent chain and substitutions)
A-The tallest chain is the parent
B- Substitution must take the lowest number
CH3
CH3
CH3
2-methylpentane
CH3
CH3
CH3
CH3
2,4-dimethylpentane
The main chain (or parent chain) must include the functional group and so may not necessarily be the longest chain.
C- In case of more than one substitution the substituents with alphabetical priority has the lowest numbering
D- Write name in alphabetical order
4- In case of presence of halogens (Cl, F, Br, I) write the name of the halogen (Chloro, Floro, Iodo, Bromo)
CH3
CH3
CH3
Cl
2-chloro-4-methylpentane
CH3
CH3
1-ethyl-3-methylcyclohexane
CH3
CH3
1,3-dimethylcyclohexane
5- In Case of presence of two function groups. A- In case of alkane chain and alkene chain the alkene is the parentB- Alkane – cyclo alkane the larger is the parentC- Alkane, Alkene, alkyne – benzene the Benzene is the parentD- Benzene – any other group than the alkane, alkene, and alkyneBenzene is the substitution and called phenyl.
CH3
OH
4-phenylbutan-2-ol
order of group priority is alkane –alkene- alkyne – amine – alcohol – ketone – aldehyde - acid
OH
COOHCH3
3-hydroxy-pentanoic acid
CH3
OH
NH2
2-aminobutan-1-ol
Aromatic compounds
Mono-substituents: CH3
methylbenzene
Di-substituents
Br
Br
Br
Br
Br
Br
COOH
NO2
1,2-dibromobenzene 1,3-dibromobenzene 1,4-dibromobenzene 2-nitrobenzoic acid
o-dibromobenzene m-dibromobenzene p-dibromobenzene o-nitrobenzoic acid
CH3
F
1-fluoro-3-methylbenzene
Cl
ClCl
1,3,5-trichlorobenzeneNH2
OHO
3-aminobenzoic acid
Practice. . .
OHCH3
CH3
CH2CH2C(OH)(CH3)2
4,4-dimethylcyclohexanol
2-methyl-4-phenyl-2-butanol
A primary carbon has one other C directly bonded to it. A secondary carbon is directly bonded to two other C’s. A tertiary carbon is directly bonded to three other C’s. Multivalent atoms are 1º, 2º, or 3º by bonding to C’s. Univalent atom or group not really 1º, 2º, or 3º on its own
- ID depends on type of carbon it is bonded to.
Primary, Secondary, Tertiary
