formaldehyde - Sciencemadness Dot Org

REACTIONS WITH ORGANIC ACIDS AND ESTERS 197
SCHgCOCHsCOOC^ 4- CHsO(aq)
CHJCOCBCOOCHB
I
I
CHaCOCHCOOCsHa
The ester, which separates from the reaction mixture as an almost colorless,
water-immiscible liquid, decomposes on heating and cannot be distilled,
Klages and Knoevenagel 17 , who first reported its preparation, carried out
this reaction in the presence of pyridine or diethylarnine. In the presence
of these catalysts, the condensation is highly exothermic and readily proceeds
further with formation of cyclic products, as indicated in this sequence
:
O O
C
/ \
HaC CHCOOC2H5
O
\
c
CHa
/
/ \
H COOCsHs
O
C
/ \
HSC GHCOOCaHs
HO
/ \ /
H,0 C
/ \
H COOC2H5
C H
/ \ /
HC C
I \
I COOCsHs
\ /
c
/ \
H COOCsHs
Methylene bis-(ethyl acetoacetate), as isolated from the reaction of formaldehyde
and acetoacetic ester, possesses a high degree of purity and reacts
quantitatively with ammonia to give a dihydrolutidine dicarboxylic ester
(m.p. 174r-176°C) ir :
CHsCOCHCOOCsHs
i
1
CHaCOCHCOOCsHs
NH^Cg)
CEt—C:C—COOC5HB
/ \
EDN" CH2 -h 2HaO
\ /
CH3—C:C—COOCsHs