Butan-2-ol is heated with red phosphorous and bromine. Find the...

The reaction of butan-2-ol with red phosphorus and bromine yields 2-bromobutane.

$CH_3-CH(OH)-CH_2-CH_3 \xrightarrow{P/Br_2} CH_3-CH(Br)-CH_2-CH_3$

The product, 2-bromobutane, contains exactly one chiral carbon atom (the second carbon is attached to four different groups: $-H$, $-Br$, $-CH_3$, and $-CH_2CH_3$).

The number of optical isomers for a compound with $n$ dissimilar chiral centers is given by $2^n$.

For $n = 1$, the number of optical isomers is $2^1 = 2$. These correspond to the (R) and (S) enantiomers.

Answer: Two