NOMENCLATURE PART 1

 NOMENCLATURE 

Mainly three systems are adopted for naming an organic compound -

1. Common names or Trivial system 
2. Derived system 
3.  IUPAC system or Jeneva system

Trivial System :

Initially organic compounds are named on the basis of source from which they were obtained for

S.no	Organic Compound	Trivial Name	Source
1.	CH3OH	Wood spirit or Methyl spirit	Obtained by destructive distillation of wood
2.	NH2CONH2	urea	obtained from urine
3.	CH4	Marsh gas (fire damp)	It was produce in marshy places
4.	CH3COOH	vinegar	obtained from acetum- i.e vinegar
5.		Oxalic acid	obtained from oxalis plant
6.	HCOOH	Formic acid	Obtained from formicus (red ant)
7.		Latic acid	Obtained from sour milk
8.		Malic acid	obtained from apples

9.	CH3CH2CH2COOH	Butyric acid	obtained from butter
10.	CH3(CH2)4COOH	Caproic acid	obtained from goats

Some typical compounds in which common & trivial names are also differ.

s.no	Compound	Trivial Name	Common name
1.	CH4	Marsh gas	Methane
2.	CH3OH	Wood spirit	Methyl alcohol
3.	CH3COOH	Vinegar	Acetic acid
4.		Acetone	Dimethyl ketone
5.		Acrolein	Acryl aldehyde
6.		Pyualdehyde	Tertiary valer aldehyde

Comman Name : 

R is termed as alkyl

S.no	Compound	Name
1.	R-X	Alkyl halide
2.	R-OH	Alkyl alcohol
3.	R-SH	Alkyl thioalcohol
4.	R-NH2	Alkyl amine
5.	R-O-R	Dialkyl ether
6.	R-S-R	Dialkyl thioether
7.		Dialkyl ketone
8	R-NH-R	Dialkyl amine
9		Trialkyl amine
10	R-O-R'	Alkyl alkyl' ether
11		Alkyl alkyl' ketone
12	R-S-R'	Alkyl alkyl thioether
13	R-NH-R'	Alkyl alkyl amine
14		alkyl alkyl' alkyl" amine

 Position of double bond : 

In an unsaturated hydrocarbon if the position of double bond is on Ist or last carbon then it's prefix will be 𝝰(alpha) if it is on 2nd carbon it is termed as ꞵ (Beta) & then 𝛾(gamma) & 𝞭 (delta) and so on.

Example : 

H₂C=CH–CH₂–CH₃                         𝝰-butylene 

H₃C–CH=CH–CH₃                       ꞵ -butylene 

H₃C–CH₂–CH=CH₂                         𝝰-butylene 

H₂C=CH–CH₃          or                  propylene         (Both are same positions propylene, isobutylene)

   
                            Isobutylene 

CH₃–CH₂–CH=CH–CH₂–CH₃                    𝛾-hexylene 

CH₃–CH₂–CH₂–CH=CH–CH₂-CH₂–CH₃   𝞭-octylene

Common - Naming of dihalides :

 (a) When two same halogen atoms are attached to the same carbon such compounds are called Gemdihalides.

 (b) Common names of such compounds are alkylidene halides.

Example:

Exception :

 

(c) When two same halogen atoms are attached to adjacent carbon, these are called as vicinal dihalides. Common names of such compounds are alkylene halide.

(d) When two same halogen atoms are attached at the two ends of a carbon chain its common naming will be polymethylene halide.

 'poly' word indicates the number of –CH₂– groups. 

–CH₂–            2    3     4          5       6 

Poly              di    tri  tetra   penta   Hexa

Example :

Exception :

 

Common - Naming of di-hydroxy compounds : 

(a) When two –OH groups are attached to adjacent carbon's they are termed as alkylene glycol.

(b) When two –OH groups are attached at the two ends of a carbon chain, these compounds are named as polymethylene glycol. 

Poly ⟶Number of >CH₂ groups.

Example:

Exception:

Ex : Make the structure of following organic compounds -

1.Isopropylidene Bromid

2.Isobutylene glycol 

3.Trimethylene glycol

Common - Naming of the functional group having carbon :

                        chart 1

S. No.	Functional group	suffix
1.		Aldehyde
2.		Oic acid
3.		yl halide
4.		Amide
5.		o-nitrile
6.		o-isonitrile
7.		ate
8.		ic-anhydride

 Prefix : 

1. Carbon ⟶ Form 
2. Carbon ⟶Acet 
3. Carbon ⟶ Propion

3C + (=) double bond = Acryl 

4C + double bond = Croton

Example :

Nomenclature of Ester :

The group which is attached to the oxygen is written as alkyl & the remaining structure is named same as defined in chart-1.

Examples :

Nomenclature of Anhydride :

 Rule : Add the total number of carbon atoms & divide by 2, the quotient will give you the number of carbon atom now name it according to Chart-1

Total /2 = Quotient = Number of C atom

 

If R≠ R', You need not to find out Quotient. Divide it in two parts as above & name it by suffixing ic anhydride (alphabetically) 

Derived System : 

According to this system any compound is given name according to the parent name of the homologous series. This system is reserved for the following nine homologous series.

Chart -2

S.No	Name of Homologous series	Derived Name	structure of group
1	Alkane	Methane
2	Alkene	Ethylene
3	Alkyne	Acetylene
4	Alkanol	carbinol
5	Alkanal	Acetaldehyde
6	Alkanoic	Acetic acid
7	Alkanoyl halide	Acetyl
8	Alkanamide	Acetamide
9	Alkanone	Acetone

IUPAC NOMENCLATURE PART 2