Question

An aldopentose A, is oxidised to a diacid, B, which is optically active Compound A is also degraded to an aldotetrose, C, which undergoes oxidation to an optically inactive diacid D. Given that A has the D configuration what are the structures of A through to D? Justify your answers.

Answer 1

An alco pentose @ aldopentase which with have D-config weaton configuration all 10- (-) Ribose & D-(-) Arabinose y D-(+) Xy lose , DL-)-Lyxose out of these only arabinose and tyvose give optically actune di acid cupon oxidat con (by HNO₂) But Degradation (wore) of Lyxose ques thereose which gives optically actine diacid with HNO₃ ! and Degradation (wohl) of Alabiriose gillres erythose [aldo tetrose), gies meso Coptically inactive) diacid ebou oxidation. This A aldo pentose is D-(-) Arabinose cs Scanne CamScanne

ques CHO Ho 4 ton HEO CH₂OH D-- Arabinose active quies optically compound oxidation tot coon This is diacia - Active Aldaric acid) Coptically active / coor Lo-arabinaric acid O on degradation C » aldotetrose gine acion d CHO CHO H wohl Degradation ои OH Hou o CH2on b-canythrose) СОО и having plane of symmetry) von Coptically Meso Tartaric Scanned with - acio CamScanner inactie dia cid) (Inactive 'coon Aldaric aul

Therefore I is is is is D-(-) Arabinose - arabinaric acid D- erthyrose meso tartaric acid. I c I D Cam