Group 13 sulfides hydrocarbons

A series of ultraviolet (UV)-visible spectra for PbPMAO with different ratios of carboxylic groups and hydrocarbon chains that reacted with HjS and lasted 150 h is shown in Fig. 4. The result from UV-visible spectra shows that the PbS particles within the LB matrix are relatively monodispersed. The exciton peak of quantum-sized PbS was obviously detected. Meanwhile, it can be deduced that the aggregate of the sulfides within PMAO LB films is smaller than that formed in stearic acid LB films. PbS two-dimensional domains or lines have also been produced, as we reported previously [17]. 

The stability of the various cumulenic anions depends to a large extent upon the nature of the groups linked to the cumulenic system. Whereas solutions of lithiated allenic ethers and sulfides in diethyl ether or THF can be kept for a limited period at about O C, the lithiated hydrocarbons LiCH=C=CH-R are transformed into the isomeric lithium acetylides at temperatures above about -20 C, probably via HC C-C(Li )R R Lithiated 1,2,4-trienes, LiCH=C=C-C=C-, are... 

The functional group ia collectors for nonsulfide minerals is characterized by the presence of either a N (amines) or an O (carboxyUc acids, sulfonates, etc) as the donor atoms. In addition to these, straight hydrocarbons, such as fuel oil, diesel, kerosene, etc, are also used extensively either as auxiUary or secondary collectors, or as primary collectors for coal and molybdenite flotation. The chain length of the hydrocarbon group is generally short (2—8 C) for the sulfide collectors, and long (10—20 C) for nonsulfide collectors, because sulfides are generally more hydrophobic than most nonsulfide minerals (10). 

Introduction of a sulfur atom into saturated hydrocarbons leads to a considerable decrease, by an order of magnitude, in the yield of radicals [G(radicals) for hydrocarbons 420]. This was explained as due to the existence of low-lying d-orbitals at the sulfur atom. This explanation agrees with the observation that this decrease is smaller in the case of insertion of a SO group, as there are four p electrons of the S atoms which may be excited at the d-orbital for sulfide and only two p electrons in the case of sulfoxides. Additional proof is that for sulfones, where there is no available p electron, the yield of the radicals [G(radicals) = 3.7 for tetramethylene sulfone] is about the same as for hydrocarbons. 

The headspace volatiles from biological fluids are comprised of a chemically diverse group of substances of widely different polarity most are alcohols, ketones, aldehydes, O- and M-hetrocyclic cosqpounds, isocyanates, sulfides, and hydrocarbons containing from 1 to 12 carbon atoms and with boiling points generally less than 300 C [342]. Quantitative differences in... 

If one or more of the hydrogen atoms of a non-metal hydride are replaced formally with another group, R—e.g., alkyl residues—then derived compounds of the type R-XHn-i, R-XHn-2-R, etc., are obtained. In this way, alcohols (R-OH) and ethers (R-O-R) are derived from water (H2O) primary amines (R-NH2), secondary amines (R-NH-R) and tertiary amines (R-N-R R") amines are obtained from ammonia (NH3) and thiols (R-SH) and thioethers (R-S-R ) arise from hydrogen sulfide (H2S). Polar groups such as -OH and -NH2 are found as substituents in many organic compounds. As such groups are much more reactive than the hydrocarbon structures to which they are attached, they are referred to as functional groups. 

In the group, the most familiar members are the oxides, halides, hydrides (including the hydrocarbons), nitrides, sulfides, and carbides. Many methods are available for the preparation of binary compounds, and the most general ones will be illustrated by exercises. 

NOXIOUS CAS. Any natural or by-product gas or vapor that has specific toxic effects on humans or animals (military poison gases are not included in this group). Examples of noxious gases are ammonia, carbon monoxide, nitrogen oxides, hydrogen sulfide, sulfur dioxide, ozone, fluorine, and vapors evolved by benzene, carbon tetrachloride, and a number of chlorinated hydrocarbons. Oases that act as simple asphyxiants are not classified as noxious. See also Pollution (Air). 

The utility of sulfur K-edge X-ray absorption spectroscopy for the determination and quantification of sulfur forms in nonvolatile hydrocarbons has been investigated. X-ray Absorption Near Edge Structure (XANES) spectra were obtained for a selected group of model compounds, for several petroleum asphaltene samples and for Rasa coal. For the model compounds the sulfur XANES was found to vary widely from compound to compound, and to provide a fingerprint for the form of sulfur involved. The use of third derivatives of the spectra enabled discrimination of mixtures of sulfide and thiophenic model compounds, and allowed approximate quantification of the amount of each component in the mixtures, in the asphaltene samples and the coal. These results represent the first demonstration that nonvolatile sulfide and thiophenic sulfur forms can be distinguished and approximately quantified by direct measurement. 

Substitution of alkyl or aryl hydrocarbon groups, such as phenyl and methyl for H on hydrogen sulfide, H2S, leads to a number of different organosulfur thiols (mercaptans, R-SH) and sulfides, also called thioethers (R-S-R). Structural formulas of examples of these compounds are shown in Figure 1.19. 

Phosphine oxides and sulfides have the general formulas illustrated below, where R represents hydrocarbon groups ... 

The second, even more convenient, method to determine double-bond positions in unsaturated hydrocarbons is the use of dimethyldisulfide derivatives (Francis and Veland, 1981 Carlson et al, 1989 Howard, 1993). In this approach, alkenes are dissolved in a carbon disulfide and iodine solution and kept overnight. The reaction yields a derivative with methyl sulfide substituents on each of the carbons that comprised the double bond. If the double bonds are separated by four or more methylene groups, the reaction proceeds... 

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