Question

How many meso isomers are possible for $2,3,4-pentanetriol$ :

• A. $1$
• B. $2$
• C. $3$
• D. none of these

Answer 1

The correct option is A $1$

$[C-\stackrel{OH}{\stackrel{|}{\underset{\ast }{C}}-}\stackrel{OH}{\stackrel{|}{\underset{\ast }{C}}-}\stackrel{OH}{\stackrel{|}{\underset{\ast }{C}}-}C]$

One meso isomer is possible for $2,3,4-pentanetriol.$

For symmetrical $2,3,4-pentanetriol$ with odd number of asymmetric C atoms, the number of meso isomers
$=2^{\frac{n+1}{2}-1}$
$=2^{\frac{3+1}{2}-1}$
$=1$