206 REPORT—1904. 
2 
Hydroxymethylene (formyl) ig is usually regarded as the enolic 
modification, HO.CH : oxi IP ; "and formylacetylacetone, 
H.CO. seo CH,),2HO.CH : C(CO.CH;) 
is a stronger acid than acetic. 
3. Esters.—The possibility of enolisation is indicated in the formule 
assigned to ethylic sodiomalonate, EtO.CO.CH : C(OEt).ONa, and ethylic 
sodiocyanacetate, CN .CH.C(OEt).ONa,? and is of importance in deter- 
mining the optical inversion of carboxylic acids. In the case of ethylic 
dicarboxyglutaconate, (CO,Et),C : CH.CH(CO,Et)., and ethylic isa- 
conitate, CO,Et.CH : CH.CH(CO,Et),,? the ester itself gives a blue 
coloration with ferric chloride and is at least partially enolic. The 
green modification of ethylic succinosuccinate is not represented in a 
satisfactory manner cde either of the conventional formule, 
COH.CH, 
ponerse doe CO,Et and CO,Et.c’ Sc.co, Et, 
oes re, \cH,.COH” 
but the colour would be accounted for if it were formulated as 
OH: Et 
staa og é Sa: OZ. “ 
HOY« ‘as@tGoH7...;>OB,: 
and if this be correct the enolised ester is actually the stable form under 
certain conditions. 
4. Phenols.—The strong enolic character of the phenols is lessened 
by substitution and by reduction, probably owing to the weakening 
of the benzene ring. Psewdo-phenol, O : OL and pseudo-quinol, 
a4 
H 
0:C,H K are as unstable as psewdo-camphor or pseudo-acetone, though 
derivatives of this type are known,‘ hut dihydroresorcinol appears to 
contain at least one keto-group and yields a dioxime, whilst phloroglucinol 
yields a trioxime, though its absorption spectrum shows that it is almost 
wholly enolic in solution.” 
5. Amides.—These rarely, if ever, exist in an enolic form, even when 
forming part of an aromatic ring as in isatin, the a and y pyridones 
(hydroxypyridines), 
CH.C(OH) CH.CH 
cH? Sw and HO.cZ Sn, 
\cH : CH 7% \cH : CH 
1 Claisen, Ann. 1894, 281, 306. 2 J. F. Thorpe, Trans. 1900, 77, 923. 
8 Guthzeit and Dressel, Ber. 1889, 22, 1418. 
4 See especially Auwers, Ber. 1902, 35, 443455, who gives asummary of recent 
work on the pseudo-quinols. 
5 Hartley, Dobbie, and Lauder, 7rans. 1902, 81, 929. 
