( 452 ) 



Chemistry. — Professor Lobry de Bruyn prcseiits a couiiriunication 

 from Mr. W. x\lberda van Ekenstein on: "Dibemal- and 

 benzaJm dhf/k/hicosir/eb'.'' 



(Communicated in the meeting of December 19, 1903). 



While derivatives of forinakleliyde ma^' be obtained from sugars 

 by iisiijg sulphuric or phosphoric acid as condensing agent ^) it is 

 also possible to effect the condensation of aromatic aldehydes and 

 ketones with these substances l)y using phosphoruspentoxide. 



In the case of benzaldehyde the desired substances are obtained 

 by mixing two parts of the sugar in a mortar with three parts of 

 the freshly distilled aldehyde and then adding with continuous 

 stirring three parts of PJ^^. The clear mass is left for half an hour, 

 then diluted with iced-^vater and the precipitate is dissolved in 

 methylalcohol. 



From this solution the pentosederivatives are obtained as well- 

 crystallised products while the aldohexoses (also fructose and sorbose) 

 yield thick syrups ^vhich as yet have not been made to crystallise. 

 The pentosederivatives contain two benzal-groups and no hydroxyl- 

 group. For this reason their constitution is probably analogous to 

 that of the formal derivatives, for instance. 



TT r\ /\ The hexosederivalives are also formed 



/ I ^CH. fi'om two mol. of benzaldehyde; judging 



y C — (k from their behaviour towards aceticanhy-^ 



I dride they still contain a hydroxy Igroup. 



\^^ ^\ It is not improbable that tlie substances 



^A^^ \/iTT obtained from the hexoses are mixtures of 



I / isomers. 



H.3C — (v When these aldehydederivatives are 



formed, the carbonylgrou[)s have disappeared as in the case of the 

 compounds derived from formaldehyde; consequently they do not 

 rednce Fehling's solution. The number of bcnzalgroups may be 

 readily determined by boiling with phenylliy(b'azine dissolved in 

 dilute acid and weighing the benzalpheiiylhydrazone which has been 

 formed. 



Dibenznlarah'mo.'ie, melting point 154°, [«]n=: -|- 27° (in methyl- 

 alcohol). Found C 69.8, H 5.6. Calculated from ('„Hi.Oj : C 69.9, H 5".5. 

 Completely hydrolysed b^' boiling with dilute sulphuric acid ; emulsin 

 has no action. 



1) LoBUY DE Bruy.n and Alberda van Ekenstein, Proc. June 28. 19U2. 



