Isomerism

There are total 5 isomers (including stereoisomers) of compound having formula $ \mathrm{C}_{4} \mathrm{H}_{9} \mathrm{Br} $

1-bromobutane $ \rightarrow $

$ \mathrm{CH}_{3}-\mathrm{CH}_{2}-\mathrm{CH}_{2}-\mathrm{CH}_{2}-\mathrm{Br} $

2-bromobutane $ \rightarrow $

( $ d $ and $ l $ form)

1-bromo-2-methyl propane $ \rightarrow $

2-bromo-2-methyl propane $ \rightarrow $

(Molecular weight of $186 u$ is of dibromoethene. It can have 3 isomers, two geometrical isomers (cis and trans) of 1,2 dibromoethene and one $ \text { 1-1-dibromoethene. } $

Threonine is the amino acid which is consisted of two chiral carbons.

Chiral carbons are those carbon atoms which are attached to four different substituent (asymmetric).

An optically active compounds exists in two isomeric form that rotate the plane polarised light in opposite direction. This phenomenon is called optical isomerism. Among the given complexes, $\left[\mathrm{Co}\left(\mathrm{NH}_3\right)_3\left(\mathrm{NO}_2\right)_3\right]$ does not show optical isomerism, because it has symmetry in its structure.

Chiral molecule have at least one carbon atom which is attached to 4 different atoms or groups and it does not have an element of symmetry.

Alcohols are functional group isomers of ethers. e.g. $\mathrm{CH}_3 \mathrm{CH}_2 \mathrm{OH}$ and $\mathrm{CH}_3-\mathrm{O}-\mathrm{CH}_3$ both have same molecular formula but different functional group.

Formula of optical isomer in symmetrical structure = 2ⁿ, Here, n = number of chiral center.

There are two chiral center present in 2-bromo, 3- chloro butane.

Hence, n = 2

Number of optical isomer is = $2^n=2^2=4$