No abstract

Pyrophoric bismuth, cobalt, copper, iron, lead, nickel, and tin were prepared by the decomposition of the metal citrate, oxalate, or tartrate in vacuo at 350-450°. The rates of oxidation were first order in oxygen pressure, and the rate constants gave linear Arrhenius plots in the range -120 to +75°. The entropies of activation were very similar to the standard entropies of the reactions with 1 mole of oxygen. A compensation effect was observed which was shown to be due to the fact that the free energy of activation was approximately constant at 18 kcal mole-1 for the oxidation of all of the metals studied.

Letters and the efforts of vocational training schemes to increase the skills of young doctors in this area. Dr Aldridge cites much anecdotal evidence in support of his views. However, most caring doctors will use any agency to supplement their own care in appropriate circumstances and Dr Aldridge should recognize that some doctors and some patients find his approach intrusive and unhelpful in a doctor-patient relationship which has often been nurtured over many years.

Summary. -An NMR. investigation of the state of formaldehyde in acidic solutions has been carried out. Solutions of DCl/D,O/CD,COOD containing two sources of formaldehyde, i. e. paraformaldehyde (I) and trioxane (TI), were used for this purpose. In systems I and I1 the effect of various D,O/CD,COOD ratios, at a constant DC1 concentration, was studied, while for I1 the effect of changing DC1 concentration was also investigated. The results show that in aqueous solution, formaldehyde exists primarily as the monomeric and linear oligomeric forms of methylene glycol. Reducing the amount of D,O (at constant DC1 concentration), while increasing the CD,COOD content, results in an increase in the polymeric species and in trioxane. I n addition, substitution of water by acetic acid results in systems that are catalytically more active than aqueous solutions of the same hydrochloric acid concentration. Along with the usual polymer-monomer equilibria which exist in such solutions, side reactions of methylene glycol with the hydrochloric acid present also occur to a small extent, e.g. acetylation, substitution of OH by C1 and the Cannizzaro reaction. It is suggested that these findings will result in a better understanding of the formaldehyde crosslinking reactions in cotton cellulose.

1.r.-spectroscopic methods indicate that the short C-H * -* N distance found in the X-ray structure of 2-1 -(~-bromophenylphenylmethylene)-3-oxo-1,2-diazetidinium inner salt (I) is probably not due to strong hydrogen bonding.