Conformations and structure studies of sugar lactones in the solid state. Part I. The molecular structure of l-rhamnono- and l-mannono-1,4-lactones

The crystal structures of l-rhamnono-1,4-lactone (1) and l-mannono-1,4-lactone (2) have been determined by single-crystal X-ray diffraction. Pertinent crystal data are as follows: for 1, orthorhombic, space group P212121, a=4.8829(2), b=10.9088(8), c=13.9758(9) , V=744.4(1) 3, Dc=1.447 g cm−3, Z=4, final R=0.037 and Rw=0.035 for 1226 reflections; for 2, orthorhombic, space group P212121, a=4.8157(2), b=11.0003(7), c=13.8693(8) , V=734.7(1) 3, Dc=1.610 g cm−3, Z=4, R=0.028 and Rw=0.035 for 1586 reflections. The lactone ring of 1 adopts an envelope conformation, E3, slightly distorted toward 2T3, with φ=103.1(7)° and q=0.38(3)whereas the lactone ring of 2 adopts a perfect envelope E3 conformation, with φ=106.6(4)° and q=0.42(4) . Molecules of 1 and 2 are linked in their crystals through a three dimensional network of O−H…H hydrogen-bonding interactions that involves all hydroxyl groups as well as the carbonyl oxygen atom.