1. ORGANIC CHEMISTRY
Nomenclature of organic compounds & Functional groups identification By
Dr. Sulaiman Al Sulaimi
Assistant Professor
UNIVERSITY OF NIZWA

2. Nomenclature
It is important that organic compounds are corrrectly named so that there can be absolutely no confusion about what compounds are actually being reported or described. The International Union of Pure and Applied Chemistry (I.U.P.A.C.) which was formed in 1919, reviews to standardise nomenclature.

3. Alkanes - Nomenclature
The name of every organic molecule has 3 parts:
The parent name indicates the number of carbons in the longest continuous chain.
The suffix indicates what functional group is present.
The prefix tells us the identity, location, and number of substituents attached to the carbon chain.

4. Alkanes - Nomenclature
Prefix – Our substituents will be branches in the alkane structure A branch is another alkane minus one hydrogen – an alkyl group
Example – if CH3- is a branch on a longer chain:
CH3- is CH4 minus 1 hydrogen
Since it is a side chain it will replace the –ane suffix with –yl
CH3- is a methyl group
We can also abbreviate this group as Me-

5. Alkanes - Nomenclature
Prefixes -
Alkyl group
Structure
IUPAC name
Abbreviation
CH3-
methyl
Me-
CH3CH2-
ethyl
Et-
CH3CH2CH2-
n-propyl
n-Pr
CH3CHCH3
isopropyl or i-propyl
i-Pr
CH3CH2CH2CH2-
n-butyl
n-Bu
CH3CH2CHCH3
sec-butyl
s-Bu
(CH3)2CHCH2-
isobutyl or i-butyl
i-Bu
(CH3)3C-
tert-butyl or t-butyl
t-Bu
C6H5-
phenyl Ph

6. Alkanes - Nomenclature
The parent name, Alkanes (CnH2n+2)

7. Alkanes - Nomenclature
1. Find the parent carbon chain and add the suffix.
Note that it does not matter if the chain is straight or it bends.

8. Alkanes - Nomenclature
Also note that if there are two chains of equal length, pick the chain with more substituents. In the following example, two different chains in the same alkane have seven C atoms. We circle the longest continuous chain as shown in the diagram on the left, since this results in the greater number of substituents.

9. Alkanes - Nomenclature
2. Number the atoms in the carbon chain to give the first substituent the lowest number.

10. Alkanes - Nomenclature
If the first substituent is the same distance from both ends, number the chain to give the second substituent the lower number.

11. Alkanes - Nomenclature
3. Name and number the substituents.
Name the substituents as alkyl groups.
Every carbon belongs to either the longest chain or a substituent, not both.
Each substituent needs its own number
If two or more identical substituents are bonded to the longest chain, use prefixes to indicate how many: di- for two groups, tri- for three groups, tetra- for four groups, and so forth.

12. Alkanes - Nomenclature
4. Combine substituent names and numbers + parent and suffix.
Precede the name of the parent by the names of the substituents.
Alphabetize the names of the substituents, ignoring all prefixes except iso, as in isopropyl and isobutyl.
Precede the name of each substituent by the number that indicates its location.
Separate numbers by commas and separate numbers from letters by hyphens. The name of an alkane is a single word, with no spaces after hyphens and commas.

13. Alkanes - Nomenclature
Cycloalkanes are named by using similar rules, but the prefix cyclo- immediately precedes the name of the parent.
1. Find the parent cycloalkane.

14. Alkanes - Nomenclature
2. Name and number the substituents. No number is needed to indicate the location of a single substituent.
For rings with more than one substituent, begin numbering at one substituent and proceed around the ring to give the second substituent the lowest number.

15. Alkanes - Nomenclature
With two different substituents, number the ring to assign the lower number to the substituents alphabetically.
Note the special case of an alkane composed of both a ring and a long chain. If the number of carbons in the ring is greater than or equal to the number of carbons in the longest chain, the compound is named as a cycloalkane.

16. Alkanes - Nomenclature

17. Alkanes - Nomenclature

18. Alkanes - Nomenclature

19. Alkanes - Nomenclature
2-methylpentane
2,2-dimethylbutane
2,3,3-trimethylhexane
5-ethyl-2-methylheptane
3,3,5-trimethyloctane
2,2,3,3-tetramethylhexane

20. The Alkenes (CnH2n)
ene =one double bond, diene =two double bonds
(a) Select and name the longest carbon chain containing the double bond.
(b) Change the “ane" of the alkane name to “ene".
(c) Number the carbon chain giving the double bond the lowest possible location number.
(d) Name side chains in the usual way.

21. The Alkynes (CnH2n-2)
These are named in identical fashion to alkenes except that "ene" in the alkene name is replaced by: "yne" 1 triple bond, "diyne" 2 triple bonds
"triyne" 3 triple bonds etc.

22. COMPOUNDS CONTAINING HALOGENS AND NITRO GROUPS
The halogens (F, Cl, Br, I) and the nitro group (-NO2) are always named as prefixes in the same way as side chains on hydrocarbons. The prefixes are as follows:

23. Alcohols
-OH as the principle functional group, here “ane” is converted into “ol”

24. Priority Order

25. Aldehydes
Aldehydes formally derived from acids having a trivial name are named by adding "-aldehyde" to the trivial stem (see Section 3), otherwise the suffix “-al” is used.

26. Ketones
Ketones are named by adding the suffix "-one" to the stem of the parent carbon chain.

27. Carboxylic acids are named by identifying the longest carbon chain containing the carboxylic acid functional group and using this carbon chain as the stem for the carboxylic acid name. The ending "-oic acid" is added to the stem to indicate that the compound is a carboxylic acid.

28. Naming Esters Esters give flowers and fruits their pleasant fragances and flavors.
Name the alkyl from the alcohol –O-
Name the acid with the C=O with –ate O
 methyl
CH3 — C—O —CH3
Ethanoate methyl ethanoate (IUPAC)
(acetate) methyl acetate (common)

29. Some Esters and Their Names
HCOOCH2CH3 ethyl methanoate (IUPAC)
ethyl formate (common)
CH3CH2CH2 COOCH2CH3
ethyl butanoate (IUPAC)
ethyl butyrate (common)

30. propyl acetate (common)
Q. Give the IUPAC and common names of the following compound, which is responsible for the flavor and odor of pears (kamsari). O 
CH3 — C—O —CH2CH2CH3
Answer:
 propyl
propyl ethanoate (IUPAC)
propyl acetate (common)

31. Q. Draw the structure of the following compounds:
3-bromobutanoic acid
Ethyl propionoate
Answer:
A. 3-bromobutanoic acid Br |
CH3CHCH2COOH
B. Ethyl propionoate O 
CH3 CH2 COCH2CH3 OR
CH3CH2COOCH2CH3

33. Ethers
In the naming of ethers as alkyloxy derivatives of alkanes, it is general practice to shorten
the names of compounds containing four or less carbons to alkoxy derivatives (i.e., omit the
syllable "-yl-°'), e.g., methyloxy becomes methoxy, ethyloxy becomes ethoxy, but pentyloxy

34. Amine: The systematic method of naming amines, whereby "-amine" is added to the principal chain name is, in practice, only rarely used and an older method is in common (I.U.P.A.C. accepted) use.