Laboratory Methods of Organic Chemistry - Sciencemadness Dot Org

350 ALDEHYDE SYNTHESES
The intramolecular ketone synthesis from the chloride of hydrocinnamic
acid :
CH2
3H2.CH2.COC1 /\/\rJT
— ' Y ^ 2 +HCl.
a-Hydrindone
The direct synthesis of ketones from hydrocarbons and phosgene,
e.g.
2C6H6 + COC12 --• C6H5.CO.C6H6 + 2HC1 .
The introduction of simple or substituted formamide radicles by
the use of urea chlorides (cyanic acid and cyanic esters+ HC1).
+ C1CONH2 >- [ || C0NH 2 + HC1 .
V
In this way aromatic carboxylic acids can be prepared by the
Friedel-Crafts method.
The range of the reaction was extended by the" elegant aldehyde
synthesis of Gattermann and Koch. If a mixture of carbon monoxide
and hydrogen chloride is allowed to act in the presence of aluminium
chloride (and cuprous chloride) on toluene (benzene is less suitable),
the reaction occurs which might be expected with formyl chloride
if this substance were capable of existence.
H
\r C = N H , it is e v i d e n t t h a t h e r e a n a l d i m i n e is first
f o r m e d a n d t h e n , w h e n t h e r e a c t i o n m i x t u r e is w o r k e d u p , is c o n v e r t e d
i n t o t h e a l d e h y d e ; N H 3 is e l i m i n a t e d b y t h e a c t i o n of w a t e r . E n o l s
of t h e a l i p h a t i c s e r i e s ( e t h y l a c e t o a c e t a t e , a c e t y l a c e t o n e ) r e a c t f u n d a -
m e n t a l l y in t h e s a m e w a y . T h e u s e of m e r c u r y f u l m i n a t e , f r o m w h i c h
b y t h e a c t i o n of h y d r o g e n c h l o r i d e t h e b e a u t i f u l l y c r y s t a l l i n e c h l o r i d e