Aliphatic hydrocarbons short-chain aliphatics

Dickson AG, Riley JP. 1976. The distribution of short-chain halogenated aliphatic hydrocarbons in some marine organisms. Mar Pollut Bull 7 167-169. 

Aliphatic ketones are oxidised in both acetonitrile [1,2] and trifluoracetic acid [3] at potentials less positive than required for the analogous hydrocarbons. The oxidation process is irreversible in both solvents and cyclic voltammetry peak potentials are around 2.7 V V5. see. Loss of an electron from the carbonyl oxygen lone pair is considered to be the first stage in the reaction. In acetonitrile, two competing processes then ensue. Short chain, a-branched ketones cleave the carbon-carbonyl bond to give the more stable carbocation, which is then quenched by reaction with... 

Recent investigations provide new insight on the structural chemistry of dissolved organic matter (DOM) in freshwater environments and the role of these structures in contaminant binding. Molecular models of DOM derived from allochthonous and autochthonous sources show that short-chain, branched, and alicyclic structures are terminated by carboxyl or methyl groups in DOM from both sources. Allochthonous DOM, however, had aromatic structures indicative of tannin and lignin residues, whereas the autochthonous DOM was characterized by aliphatic alicyclic structures indicative of lipid hydrocarbons as the source. DOM isolated from different morphoclimatic regions had minor structural differences. 

The helper effects of DOPE and cholesterol appear to be hydrocarbon chain-specific. This is demonstrated in studies of their mixtures with a series of alkyl acyl carnitine esters (alkyl 3-acyloxy-4-trimethylammonium butyrate chloride) tested with CV-1 cell culture (monkey fibroblast) [127]. The influence of the aliphatic chain length (n - 12-18) on transfection in vitro was determined using cationic liposomes prepared from these lipids and their mixtures with the helper lipids DOPE and cholesterol (Fig. 30). Both helper lipids provided for significant transfection enhancements in an apparently chain-specific manner, with the highest effects found for short-chain lipids with diC12 0 and diC14 0 chains in 1 1 mixtures with the respective helper lipid. 

There are liquid PBAs that are volatile and change from a liquid to a gaseous state when heated to the plastic processing temperatures. They are short-chain chlorinated and fluorinated aliphatic hydrocarbons (CFCs). Although they can be used over a wide temperature range and at low (atmospheric) pressures, they have been gradually discontinued due to their role in the reduction of stratospheric ozone.249 Other PBAs are reviewed in Table 8.2. 

Aliphatic hydrocarbons include straight chain and branched structures. Industrial solvents, petroleum hydrocarbons, and the linear alkyl benzene sulfonates (LAS) are the primary sources of aliphatic hydrocarbon pollutants. Many microorganisms utilize aliphatic hydrocarbons as carbon sources. Long-chain -alkanes are utilized more slowly due to the low bioavailability that results from their extremely low solubility in water. In contrast, short-chain rc-alkanes show a higher aqueous solubility. 

Since most TPH contamination involves a complex mixture of hydrocarbons, it is unlikely that aqueous readings beyond the NAPL zone will be near the limits of solubility (based on assumptions of a pure hydrocarbon type in equilibrium with water). If concentrations are near or above solubility limits, NAPL was probably present in the sample. TPH materials are relatively insoluble in water, with only the BTEX chemicals or some short-chain aliphatic hydrocarbons showing any appreciable potential for water solubility. When they are part of complex mixtures, the individual components never reach the concentrations predicted from their solubility constants as individual chemicals. For example, chemicals like benzene or toluene, which may constitute a small percentage within an initial bulk product like gasoline, jet fuel, or diesel fuel, have a much greater tendency to stay dissolved in the NAPL system than to become integrated into the water-based system beyond the NAPL boundary. Therefore, the effective solubility of these chemicals as part of a complex mixture is less than it would be in a release of the pure chemical. 

The CMC of the surfactant in the aqueous phase is changed very little by the presence of a second liquid phase in which the surfactant does not dissolve appreciably and which, in turn, either does not dissolve appreciably in the aqueous phase or is solubilized only in the inner core of the micelles (e.g., saturated aliphatic hydrocarbons). When the hydrocarbon is a short-chain unsaturated, or aromatic hydrocarbon, however, the value of the CMC is significantly less than that in air, with the more polar hydrocarbon causing a larger decrease (Rehfeld, 1967 Vijayendran, 1979 Murphy, 1988). This is presumably because some of this second liquid phase adsorbs in the outer portion of the surfactant micelle and acts as a class I material (Section C). On the other hand, the more polar ethyl acetate increases the CMC of sodium dodecyl sulfate slightly, presumably either because it has appreciable solubility in water and thus increases its solubility parameter, with consequent increase in the CMC of the surfactant, or because the surfactant has appreciable solubility in the ethyl acetate phase, thus decreasing its concentration in the aqueous phase with consequent increase in the CMC. 

Is increased considerably by the replacement of air as the second phase at the interface by a saturated aliphatic hydrocarbon and decreased slightly when the second liquid phase is a short-chain aromatic or unsaturated hydrocarbon. 

Since the PIT of a hydrocarbon-water emulsion stabilized with a POE nonionic surfactant is, as might be expected, related to the cloud point of an aqueous solution of the nonionic saturated with that hydrocarbon (Chapter 4), these effects on the PIT of emulsions stabilized by POE nonionics are readily understood. As mentioned in the discussion (Chapter 4, Section IIIB) of the effect of solubilizate on the cloud points of POE nonionics, long-chain aliphatic hydrocarbons that are solubilized in the inner core of the micelle increase the cloud point, whereas short-chain aromatic hydrocarbons and polar materials that are solubilized between the POE chains decrease it. They have the same effect on the PIT long-chain aliphatic hydrocarbons increase the PIT and therefore tend to form stable O/W emulsions, whereas short-chain aromatics and polar additives decrease it and tend to form stable W/O emulsions (Shinoda, 1964). An increase in the length of the POE chain increases the cloud point and the PIT and consequently increases the tendency to form O/Wemulsions, consistent with the generalization that the more water-soluble the emulsifier, the greater its tendency to form O/W emulsions. 

Short-chain (SCCPs), medium-chain (MCCPs), and long-chain (LCCPs) CPs all have industrial applications and similar environmental concerns. CPs are viscous, colorless or yellowish dense oils with low vapor pressures, except for those of long carbon chain length with high chlorine content (70%), which are solid. CPs are practically insoluble in water, lower alcohols, glycerol and glycols, but are soluble in chlorinated solvents, aromatic hydrocarbons, ketones, esters, ethers, mineral oils and some cutting oils. They are moderately soluble in unchlorinated aliphatic hydrocarbons [1]. 

This reaction, however, is not usually of major importance in the environment except possibly at the low pressures and short UV wavelengths characteristic of the stratosphere. Short-chain aliphatic aldehydes such as -butyraldehyde may also absorb solar UV and cleave (in a gas-phase process) to yield CO and a hydrocarbon. 

The viscosity method for soluble polymers and the swelling method for cross-linked network polymers yield quite unambiguous values for polymer solubility parameters, so long as one is confined to a series of structurally similar solvents. For example, the data in Figure 6-1 apply to aliphatic hydrocarbons as well as to long-chain esters and ketones. Cycloaliphatic hydrocarbons and short-chain esters such as ethyl acetate deviate significantly from the curves shown. 

Aliphatic and long chain hydrocarbons are more susceptible to microbial degradation than aromatic and short chain hydrocarbons. 

Rodlike hydrocarbon LCPs exist at present only in oligomeric or short-chain lengths. They are either the fully aromatic poly-p-phenylenes [235-237a], the partly aromatic substituted poly-p-phenylenes [238-244], or the fully aliphatic staffanes [245-248]. They are all rendered rodlike because each structural unit is connected to its identical neighbors by a single bond and all these bonds are coaxial. The simplest of these polymers, and also the least tractable, are the poly-p-phenylenes ... 

Aliphatic framework molecules most common in organic acids include alkanes (saturated hydrocarbons) and alkenes (unsaturated hydrocarbons). These saturated and unsaturated aliphatic carboxylic acids may be acyclic (straight or branched chains) or alicyclic (aliphatic rings). Acyclic aliphatic monocarboxylic acids are also referred to as fatty acids (Table 1). The first five saturated acids (formic to valeric) of this type are sometimes referred to as short-chain, low-molecular-weight, or volatile fatty acids. Although a nomenclature for these acids has been established by the International Union of Pure and Applied Chemistry (lUPAC), the convention of using the trivial names for the first five saturated acids has remained. Similarly, trivial names are used for the aliphatic dicarboxylic acids (Table 2) that are saturated with two to four carbon atoms (C2-C4) and unsaturated with four carbon atoms (C4). Alicyclic carboxylic acids contain one or more saturated or partially unsaturated rings. These acids most commonly occur... 

There are 3 basic routes for the synthesis of all the compounds in this class all involve the introduction of chlorine into a short chain aliphatic hydrocarbon feedstock [2, 14, 15, 19, 20, 50]. 

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