Page 44 - FPGEE Medicinal and Organic Chemistry Q&A Book

Krisman

CH CH CH CH (1-Butene)
3 2 2
600°C CH 3 CH CH CH 3 (2-Butene)
CH CH CH CH
3 2 2 3
CH 3 CH CH 2 (Propene)
n-Butane
CH CH (Ethylene)
2 2

(Fig: 11.28)

- +
CH CH Cl + CH CH O Na CH CH O CH CH + NaCl
3 2 3 2 3 2 2 3
Ethyl chloride Sodium ethoxide Diethyl ether

(Fig: 11.29)

O O
Baeyer's reagent is an alkaline solution of
NaOH
potassium permanganate, which is a powerful + H C OH
2 H C H CH 3 OH
oxidant. Reaction with double or triple bonds
Formaldehyde Methanol Formic acid
in an organic material causes the color to fade
(No a- hydrogen)
from purplish-pink to brown. For example, the
reaction of propylene with potassium perman-
hydrogen)
(a-
ganate would yield propylene glycol and the H
O
purple color of KMnO is removed by the reac- NaOH
4 H C C H No reaction
tion.
OH OH H
KMnO
4 Acetaldehyde
CH CH CH CH 3 CH CH 2
3 2
Propylene H O Propylene glycol undergo Cannizzaro reaction whereas acetalde-
2
hyde wouldn’t react.
495. (a) The Cannizzaro reaction, named after 496. (d) As we learned previously, Cannizzaro
its discoverer Stanislao Cannizzaro, is a chemi- reaction is when 2 molecules of formaldehyde
cal reaction that involves the base-induced dis- are heated in the presence of NaOH, methanol
proportionation of an aldehyde lacking a a- and formic acid are formed. However, when we
hydrogen. When heated with concentrated select two different aldehydes, each lacking a-
NaOH, one half of the aldehyde molecules are hydrogen, and they heated in the presence of
oxidized to carboxylic acid and the other half NaOH, the reaction is called a Crossed
are reduced to an alcohol. Aldehydes with a- Cannizzaro reaction. For example, when ben-
hydrogens do NOT undergo this reaction; zaldehyde and formaldehyde (two different al-
instead they undergo aldol condensation. dehydes) are heated in the presence of NaOH,
A carbon atom next to the carbonyl benzyl alcohol and formic acid are formed.
group is called an a-carbon. A hydrogen at-
tached to an a-carbon is known as an a-
hydrogen. Therefore, formaldehyde would

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