The crystal structures of phosphorus diiodide and phosphorus sesquisulfide were studied by X-ray diffraction. The structure of P2I4 was obtained from Patterson and Fourier projections and further refined by least square procedures. The arrangement of the P2I4 molecules in the crystal is essentially dictated by close packing of the iodine atoms. The key to the structure of P4S3 was a Fourier projection on the (xz) plane, for which inequalities had provided the signs. The y parameters were found from a (yz) projection. The P4S 3 molecules are cage-like, and their arrangement corresponds to hexagonal closest packing.

This work was undertaken for the purpose of further investigating the effects of alkyl substitution in aromatic compounds at positions remote from the point of substitution, and of learning how these effects vary with the nature of the alkyl group. Previous work in this field has led to no clear-cut explanations, and virtually no work has been done with meta alkyl substituents. The two series of compounds chosen for study were the meta and the para alkylbenzenediazonium fluoborates. The reactions of these substances with water to give the phenols was studied to give some additional information on the effect of alkyl groups. The ortho alkyl compounds were purposely omitted, because extraneous factors enter in, partly because of steric hindrance.

Abstract Not Available.

The research establishes the structure of the diterpene, cassaic acid. In addition, the configurations at the six asymmetric centers present in cassaic acid have been assigned. A degradative compound, which has also been obtained by synthesis, has been converted into a substance which on treatment with a Reformatsky or Wittig reagent, followed by mild oxidation, should provide cassaic acid acetate methyl ester. Resolution at a suitable stage would then complete the total synthesis of cassaic acid and cassaine, the beta-dimethylaminoethanol ester of cassaic acid.

Abstract Not Available.

Abstract Not Available.

Before the work was carried out, which is reported on in detail in the next section, a series of preliminary experiments was performed. These were designed to show the effects of various physical and chemical agents on the speed of the bromination and the configuration of the products. It was found that the addition of almost any solid to the hydrocarbon to be brominated very greatly increased the time necessary for the bromination to take place. This was true with iodine, anhydrous AlCl3, powdered sulphur, and powdered glass. The use of benzoyl peroxide and myristoyl peroxide as catalysts were failures in that these materials also slowed down the rate of substitution. All of these instances are probably examples of the breaking of the chain reaction of bromination. Inert liquid foreign materials, such as nitrobenzene and ethyl acetate, also slowed down the reaction, probably for the same reason. Only two factors were noticed which would materially speed up the bromination. First, the presence of small amounts of water very greatly reduced the time required for bromination, but when the products were distilled it was found that they consisted very largely of polysubstituted derivatives. This is in line with the findings of several earlier investigators. Secondly, as to be expected, it was found that intense activation of the reactants by light, greatly increased the speed of the reaction. It was hoped that a definite contribution could be made to the knowledge of paraffin bromination.

From the results of this investigation the order of adsorption of the ions by precipitated barium sulphate is: ferrocyanide > nitrate > nitrite > chlorate > permanganate > ferricyanide > chloride > bromide > sulphocyanate > iodide, the ferrocyanide ion being adsorbed the most and iodide the least. From a consideration of this order and of the absolute amount of adsorption in each case we find very little reason to place much credence in Schulze's law. Although we find a quadrivalent ion the most strongly adsorbed, we find four univalent ions more strongly adsorbed than the trivalent ferricyanide. Furthermore, contrary to what is implied in Schulze's law, we find a very wide variation in the amount of univalent ions adsorbed. This amount varies from 8.482 gram anions per 100 mols for nitrate to 0.056 gram anions per 100 mols for iodide ion. If the adsorption values are expressed in gram anions instead of gram equivalent anions the order becomes: nitrates > nitrites > chlorate > ferrocyanide > permanganate > chloride > ferricyanide > bromide > sulphocyanate > iodide, the nitrate ion being adsorbed the most and the iodide the least. Here there is nothing even to suggest Schulze's law.

Cadmium selenide (CdSe) quantum dots (QDs) are colloidal semiconductor nanoparticles (NPs) that are nanometer sized fragments of the corresponding bulk crystals. They are being probed as a very interesting system for their applications in LEDs, solar cells and biomedical labeling because of their rich photophysics arising from their size dependent optical and electronic properties and flexible processing chemistry. 1-Octadecene was the only non-coordinating solvent used for the synthesis of CdSe NPs. It was imperative to understand the chemistry of synthesis of CdSe NPs using other non-coordinating solvents. Also, there is a constant search for the greener, cheaper, reproducible and scalable methods for the synthesis of CdSe NPs while not compromising on their quality. Towards the above mentioned goals, the use of heat transfer fluids was successfully demonstrated as cost-effective alternative solvents for quantum dot synthesis. Heat transfer fluids (HTF) are a class of organic liquids commonly used in chemical process industries to transport heat between unit operations. The solvents were found suitable for the hot injection synthesis of QDs while reducing the cost of the raw materials. These solvents were found to slow the growth kinetics of the CdSe NPs, leading to greater control over QD diameter. Although the chemistry of synthesis of CdSe spherical and rod shaped particles were well understood, the synthesis of tetrapod shaped NPs with uniform size and shape is especially difficult to carry out at a large scale. Post-synthesis separation can be applied though this leads to additional processing steps and reduced particle yields. Cationic surfactant ligands were discovered to lead to the successful formation of tetrapod shaped CdSe NPs with highly uniform arm lengths, arm widths and shape. Typical selectivity values for the tetrapod morphology exceeded 90%, much higher than the previously reported values of 40%. The cationic surfactant ligands were found to induce anisotropy during the growth of the CdSe NPs, with cetyltrimethylammonium bromide (CTAB) and didodecyldimethylammonium bromide (DDAB) leading to the specific tetrapod shape. Optimization of the synthesis procedure led to the control over the range of dimensions of the tetrapod shaped particles. The uniformity of size and shape of the CdSe tetrapodal NPs were found to be very sensitive to the ratio of the surfactants and the precursors. It was also observed that the presence of the cationic surfactants led to the exclusive formation of zinc-blende nuclei which is indispensable for the growth of nuclei into tetrapodal NPs. The growth of CdSe tetrapodal NPs from the preformed zinc-blende CdSe NPs, just by the addition of CTAB, demonstrated the crucial role of the cationic surfactants in inducing anisotropy. These findings were helpful in gaining insight in to the nucleation and growth of the anisotropic nanoparticles. These new methods should lead to improvements in current synthesis methods of tetrapodal shaped CdSe NPs, enabling the faster development of polymer/tetrapod photovoltaic devices. These results may be applicable to other compositions, leading to opportunities for large-scale application of shaped NPs.

The nucleation and growth of carbon nanotubes (CNTs) occurs through a vapor-liquid-solid (VLS) mechanism and has been explored with an emphasis on the catalyst species used to initiate nucleation and sustain growth. Specific trends in growth density, diameter, length, and growth rates have been observed as features such as the catalyst source, concentration, and elemental composition were altered. The catalyst systems studied include the nanocluster [H xPMo12O40⊂H4Mo72Fe 30(O2CMe)15O254(H2O) 98] (FeMoC), spin-on-catalysts, and discrete bimetallic nanoparticles. Combining the catalytic properties of single elements into bimetallic combinations has proved be an effective approach towards increasing nanotube yields and establishing control over CNT diameters and lengths. Spin-on-catalyst studies with Fe, Co, and Fe/Co mixtures suggest that nanotube diameters and lengths can be controlled by varying the ratio of the two metals. A cobalt rich system yields high densities of short tubes with narrow diameters while iron rich systems favor longer nanotubes, lower densities, and larger nanotube diameters. Iron catalysts and Fe/Co mixtures are also active towards nanotube re-growth, including new tubes, nanotube amplification, double growth, and etching when re-exposed to a growth environment for a second time. Bimetallic combinations of Cu-Fe-O, Co-Fe-O, and Mn-Fe-O in the form of discrete nanoparticles with diameters ca. 5--7 nm have been shown to be catalytically active towards the formation of vertically aligned-CNT carpets from the decomposition of acetylene. Estimations for the average growth rates have been determined for each bimetallic combination by measuring the heights of the carpets which they produce. From these observations it has been shown that Cu-Fe-O and Mn-Fe-O nanoparticles are capable of producing CNTs at almost twice the rate observed for Fe nanoparticles alone under identical growth conditions. The synthesis of ca. 5 nm Co-Fe-O nanoparticles from organometallic precursors has also been explored as a route towards producing catalyst precursors with uniform size and composition for nanotube growth. Through investigating the properties associated with bimetallic catalysts of uniform size we have been able to obtain a better understanding of CNT growth dynamics.