SynopsisPolycarbonates of methyl, ethyl, n-propyl, n-butyl, and n-hexyl 4,4bis(4hydroxy-pheny1)pentanoate and copolycarbonates with bisphenol-A of 0.5-0.9 int.rinsic viscosit,y in dioxane were prepared by a homogeneous CH2C12-pyridine method and the physical properties determined. Increasing the number of carbon atoms in the DPA est.er alcohol group from 1 to 6 decreased the initial softening temperature of the polycarbonates from 126 to 58°C.; this change also increased the solubility of the polycarbonates in aromatic solvents and in three ketone solvents. O2 transmission rates were not affected by increasing the ester chain length. C02 transmission rates increased as DPA ester alcohol chain length increased. Methyl DPA polycarbonate had the highest, tensile strength and per tent, elongation and the lowest O2 and COz t.ransmission rates.

ConclusionsIt has been shown that the effectiveness of certain divalent metal salts as esterification catalysts can be quantitatively compared and that for the Group II B series their effectiveness is inversely proportional to their ionic volume. The rates of esterification using these metal salts are not as great as for strong acids, but it is probable that the mechanism is similar and that the metal salts act as acids in the general sense.The rates of esterification differ appreciably for different primary polyols. It is also probable that these differences are related to the comparative acidity or basicity of the alcohols.It would be particularly desirable to investigate the activity of the catalysts in different alcohols. It is possible that infrared studies might show formation of a complex between the catalyst and either the alcohol or the acid or both. A number of possibilities may be formulated; at present we lack critical evidence to distinguish between them and this area provides a fruitful field for further research.

than those obtained with the samples from the meteorites, but is typical of the performance obtained with the detector in this work. CONCLUSIONSEvaluations of the photoionization detector developed indicated it to be a highly sensitive and discriminating device of considerable long-term stability. The end of the hollow discharge cathode was clean even after approximately 500 hours

Summary The experimental work has shown how molecular configurations of fatty acid glycerides affect urea complex formation. Extraction data indicate that urea will form a complex with glycerol monopalmitate, monostearate, and mono‐oleate but not under these conditions with glycerol monolinoleate or monolinolenate from mixtures containing these monoesters. Data also indicate that it is easier for urea to form a complex with monoglycerides than with diglycerides. In a mixture containing mono‐ and diglycerides of saturated and unsaturated fatty acids, urea will separate first on the basis of saturation, then secondly on the basis of the degree of esterification of the glycerol.

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