Question

Which of the following is the correct order of priority of group in D-glyceraldehyde?

• A. $OH(1), CH0(2), CH_2 0H(3) \, and \, H(4)$
• B. $OH(1), CH_2 0H(2), CH0(3) \, and \, H(4)$
• C. $CH_2 0H(1) , CHO(2), OH(3), \, and \, H(4)$
• D. $CHO(1) , OH(2),CH_2 0H(3) \, and \, H(4)$

Answer 1

Answer: (A)

$OH(1), CH0(2), CH_2 0H(3) \, and \, H(4)$

Answer 2

The structure of D-glyceraldehyde is as .The priority of groups is decided by the following rules
(i) Atom having higher atomic number gets higher priority.
(ii) If the priority cannot be decided by ruie I then the next atoms are considered for priority assignment.
(iii) Where there is a = bond or $\equiv$ bond both atoms are

$\, \, \, \,$considered to be duplicated or triplicated .$(-\overset {|^{H}} {c}\equiv0$ has
$\, \, \, \,$higher priority than --$CH_2 0H).$ Hence, the corret order
$\, \, \, \,$of priority of group in D-glyceraldehyde is as :
$\, \, \, \, \,$ $OH(1), CH0(2), CH_2 0H(3) \, and \, H(4)$