Glutaric acid and pimelic acid have analogous crystal structures. T h e CH, chains are stretched along the c-axis. the plane af the zigzag is nearly parallel to (100). Packing of the COOH groups is practically identical to that in adipic acid. This packing enforces a torsion in the molecules of the odd acids as a result of their axial symmetry. This torsion may well be the cause of the higher energy content of the +d dicarboxylic acids; an estimate of the torsion energy is made and is shown to be of the right order of magnitude.

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The velocity of the ozonisation of benzene in chloroform is proportional to the concentration of benzene and that of ozone. The reaction constant was determined a t eight temperatures between -25 and -40" C.The reaction takes place about three times more rapidly in nitroinethane than in chloroform. Aluminium chloride and ferric chloride catalyse the reaction; the velocity increases directly with the concentration of aluminium chloride. mechanism suggested in a previous publication.T h e results of our measurements are in agreement with the reaction 4 1. Introduction.Working within the framework of the researches of Wibauf and his collaborators 1 ) on the action of ozone on aromatic compounds, we have initiated an investigation into the mechanism of this reaction.In a previous paper 2 ) we have given a short description of a number of experiments, which show that the velocity of the reaction between several aromatic compounds and ozone decreases in the same order as their reactivity in electrophilic substitution reactions. Moreover boron trifluoride and aluminium chloride have a definite accelerating effect on the ozonisation of benzene derivatives. On the basis of these experiments it was concluded that the addition of ozone to these compounds takes place according to an electrophilic mechanism. Further arguments in favour of this hypothesis have been obtained by a kinetic examination of a number of ozonisation reactions. T h e results of this investigation in so far as they relate to the ozonisation of benzene are described in this communication.

The rotatory dispersion of 26 amino-acids and 5 hydroxy-acids was studied.I t was found that the carboxyl absorption-band at about 205 nm to 210 nm is optically active. L-Amino-acids as well as L-hydroxy-acids show a positive Cotton effect. For a number of amino-acids a correlation exists between peakheight and molecular structure. Except for proline, hydroxy-proline and cystine. all acids studied show very similar rotatory dispersion curves.

An investigation was made into the thermal decomposition of twenty-seven aliphatic acetates, using a micro-scale flow reactor connected to a gas chromatograph. The rate of elimination increases markedly as the degree of alkylation of the u-carbon atom becomes higher. The accelerating effect of B-alkyl substituents on the rate of elimination is small, as compared with that of a-alkyl substituents. The reactivity of the aliphatic acetates approaches a limiting value as the carbon chain is extended. The reactivity decreases on the introduction at the 8-carbon atom of an electron-attracting group and increases on the introduction of an electron-releasing group. A tentative mechanism is proposed which is based on the reversible formation of an ion-pair.