Transesterification of sunflower oil’s triglycerides by aliphatic alcohols С1–С4

Transesterification of sunflower oil triglycerides by C1-C4 aliphatic alcohols in the presence of cation exchange resin KU-2-8 with immobilized divalent metal ions has been studied. It was found that the reaction occurs at a high initial rate and the conversion of triglycerides for 180 min in presence aliphatic alcohols C1– C3 is 88.4-99.8 %. It is shown that under these conditions the rate of transesterification reaction of triglycerides with butan-1-ol is significantly lower and the conversion achieved in 180 min does not exceed 52.3 %.

The Transpiration of Terrestrial Isopods

1. The transpiration of three species of Isopoda has been investigated; Armadillidium shows the highest resistance to desiccation, Oniscus the least, and Porcellio is intermediate. 2. The permeability of isopod cuticle is limited by lipoids which impregnate the endocuticle. If the temperature is raised above the lipoid melting-point a marked increase in permeability results. 3. Isopods show a characteristic decline in transpiration rate during exposure to desiccating atmospheres. The high initial rate of evaporation is due mainly to loss of water from layers of the cuticle external to the lipoid barrier. 4. There is a progressive decrease in the permeability of the integument during desiccation. This is brought about by a shrinkage of the cuticle, which leads to a closer packing of lipoid molecules. The mechanism of this structural alteration is based on an interaction between endocuticular proteins and the ionic constituents of body fluids; in the course of desiccation the blood concentration increases and there is a corresponding decrease in the dispersion of endocuticular elements.

Oviposition Behaviour in the Two Strains of the Rice Weevil, Calandra Oryzae Linn. (Coleopt., Curculionidae)

The oviposition behaviour of the large strain of Calandra oryzae has been investigated at 20 and 25°C. and under moisture conditions equivalent to 50 and 70% R.H. The small strain of the weevil has been investigated at 25°C. and 70% R.H. At either temperature the lower humidity shortens the life of the insect and depresses the rate of oviposition so that fecundity is of a low order. Changes of temperature with a fixed humidity alter the rate of oviposition but have little effect on the total egg production. Under all conditions the pattern of oviposition remains the same, the oviposition rate rising to a peak in the earlier weeks of maturity and subsequently declining. Increasing the amount of grain leads to increasing egg production. It is unlikely that conditions for maximum fecundity were realised in the experiments. Isolating females in the early weeks of maturity leads to a high initial rate of oviposition, followed by a more rapid decline and little overall increase in fecundity. At 25°C. and 70% R.H. the fecundity of the large strain is of the order of 50% higher than that of the small strain. The distribution of eggs between grains differs in the two strains, the small strain distributing its eggs better than random, the large strain tending to overcrowd its eggs. The evidence suggests that this is due to the larger weevils' greater preference for large grains. By correlating the results with those from other sources it is nevertheless concluded that both strains tend to avoid laying in grains already containing life. The importance of this factor in oviposition behaviour is discussed.

Basic Reactions Occurring during Rubber Reclaiming. I. The Influence of Reclaiming Media, Antioxidant, and Defibering Agents on Vulcanized Natural Rubber at 195 Pounds Per Square Inch Gauge Pressure (196.6° C)

The influence of surrounding atmosphere, antioxidant, and defibering agents at 196.6° C on the hydrocarbon of rubber was studied by subjecting a laboratory prepared, pure-gum, natural rubber compound to reclaiming in the absence of any reclaiming oils or chemicals. Data obtained on the amount of acetone and chloroform extracts and on the unsaturation of the reclaims and the chloroform extracts could therefore be interpreted in terms of the effect of the factors mentioned above on the rubber hydrocarbon and not as the effect of any chemicals added to the rubber to promote reclaiming. It was found that the effect of the surrounding atmosphere during reclaiming is the predominant factor in the reaction. Acidic surrounding atmospheres result in a slow and rather uniform rate of molecular breakdown and in the formation of small amounts of oxidation products. Apparently no secondary oxidative attack occurs at the double bonds. An open steam atmosphere provides the greatest amount of oxidized products and also a high initial molecular breakdown, followed by a slow progressive increase in it as the reclaiming periods are lengthened. A decrease in the unsaturation value of the acetone extracted reclaim indicates that secondary oxidative attack at the double bonds occurs at long reclaiming intervals. Alkaline reclaiming atmospheres provide little if any oxidation products and result in a very high initial rate of molecular breakdown. Longer reclaiming periods do not change further the amount of molecular breakdown. The very small amounts of oxygen necessary to promote the reclaiming reactions, the dependence of the course of these reactions on the acidity or alkalinity of the surrounding reclaiming media, together with the high initial rate of molecular breakdown reactions under conditions where such rate would be speeded up, permit the tentative explanation of these reactions on the basis of hydroperoxidic chain reactions. Further experiments along this line are being carried out.

STUDIES ON THE FORMATION OF HEXAMINE

Rate curves have been determined for the reaction of ammonia and formaldehyde in aqueous solution at 0 °C. and 35 °C., over a range of initial mole ratios (formaldehyde: ammonia) of 0.25 to 2.0. For each set of conditions, three curves have been obtained on the basis of ammonia consumed, formaldehyde consumed, and material precipitated with mercuric chloride respectively.At 0 °C. the three rate curves tend to approximate one another in a large excess of ammonia but are widely separated in excess formaldehyde. The reverse is true at 35 °C. The reaction is characterized by a high initial rate of formation of hexamine, this rapid rate being maintained to a lower yield of hexamine the more dilute the solution. The existence of a stable by-product in excess formaldehyde is indicated by the variation in final yields of hexamine, when these are calculated on the basis of formaldehyde consumed, ammonia consumed, or material precipitated with mercuric chloride.A mechanism for the reaction has been suggested.