Question 22.11: In the following structural formulas, locate each chiral car...
In the following structural formulas, locate each chiral carbon atom.
(a) CH_{3}-\overset{\underset{|}{Cl} }{\underset{\overset{|}{Cl} }{C}} -\overset{\underset{|}{H} }{\underset{\overset{|}{OH} }{C}} -CH_{3} (b) HO-\underset{\overset{||}{O} }{C}- \overset{\underset{|}{H} }{\underset{\overset{|}{NH_{2}} }{C}}-\overset{\underset{|}{H} }{\underset{\overset{|}{H} }{C}}-OH
(c) Cl-\overset{\underset{|}{H} }{\underset{\overset{|}{OH} }{C}} -\overset{\underset{|}{CH_{3}} }{\underset{\overset{|}{OH} }{C}} -Cl
STRATEGY
Look for carbon atoms that have four different atoms or groups bonded to them. As soon as you see two (or more) identical atoms or groups, you can stop counting. The C atom is not chiral.
| C_{a} has three hydrogen atoms bonded to it. It is not chiral. C_{b} has two chlorine atoms bonded to it. It is not chiral. C_{c} has four different groups/atoms bonded to it: 1 H, 1 OH, 1 CH_{3}, 1 CH_{3}—CCl_{2} It is chiral. |
(a) \underset{a}{CH_{3}} -\overset{\underset{|}{Cl} }{\underset{\overset{|b}{Cl} }{C}} -\overset{\underset{|}{H} }{\underset{\overset{|c}{OH} }{C}} -\underset{d}{CH_{3}} |
| C_{d} has three hydrogen atoms bonded to it. It is not chiral. C_{a} has only three groups/atoms bonded to it. It is not chiral. C_{b} has four different groups/atoms bonded to it: 1 H, 1 NH_{2}, 1 COOH, 1 CH_{2}OH It is chiral. |
(b) HO-\underset{\overset{||}{O} }{C_{a}}- \overset{\underset{|}{H} }{\underset{\overset{|}{NH_{2}} }{C_{b}}}-\overset{\underset{|}{H} }{\underset{\overset{|}{H} }{C_{c}}}-OH |
| C_{c} has two hydrogen atoms bonded to it. It is not chiral.
C_{a} has four different groups/atoms bonded to it: 1 H, 1 OH, 1 Cl, 1 C—Cl It is chiral. |
(c) Cl-\overset{\underset{|}{H} }{\underset{\overset{|}{OH} }{C_{a}}} -\overset{\underset{|}{\overset{c}{CH_{3}} } }{\underset{\overset{|}{OH} }{C_{b}}} -Cl |