Paraffins compared with alcohols

Sometimes phenols where a hydroxy group replaces one or more of the hydrogen atoms has been compared with alcohols, where the -OH group is attached to a paraffinic carbon atom, whereas in case of phenols, the (-OH) group is attached to a carbon atom in an aromatic system. 

The organoleptic character of hydrocarbons has received little attention in spite of the fact that compounds such as hexane or cyclohexane have a detectable odor. Boelens (1974) reported that the members of a panel could not make any distinction between Cj i - to C)5-alkanes and the corresponding aliphatic alcohols. On the contrary, polyunsaturated hydrocarbons possess typical odor qualities and may therefore be important contributors to food flavors (Ohloff, 1978a) but their presence in coffee is limited to aliphatic volatile compounds, such as pentadiene (A.41) and isoprene (A.44), and to 5-methyl-1,3-cyclohexadiene (A.47), not forgetting the terpenes mentioned later. Nevertheless the flavoring power of these paraffins is certainly negligible as compared with the most characteristic constituents of coffee, cocoa, and tea. 

Among such oxidations, note that liquid-phase oxidations of solid paraffins in the presence of heterogeneous and colloidal forms of manganese are accompanied by a substantial increase (compared with homogeneous catalysis) in acid yield [3]. The effectiveness of n-paraffin oxidations by Co(III) macrocomplexes is high, but the selectivity is low the ratio between fatty acids, esters, ketones and alcohols is 3 3 3 1. Liquid-phase oxidations of paraffins proceed in the presence of Cu(II) and Mn(II) complexes boimd with copolymers of vinyl ether, P-pinene and maleic anhydride (Amberlite IRS-50) [130]. Oxidations of both linear and cyclic olefins have been studied more intensively. Oxidations of linear olefins proceed by a free-radical mechanism the accumulation of epoxides, ROOH, RCHO, ketones and RCOOH in the course of the reaction testifies to the chain character of these reactions. The main requirement for these processes is selectivity non-catalytic oxidation of propylene (at 423 K) results in the formation of more than 20 products. Acrylic acid is obtained by oxidation of propylene (in water at 338 K) in the presence of catalyst by two steps at first to acrolein, then to the acid with a selectivity up to 91%. Oxidation of ethylene by oxygen at 383 K in acetic acid in... 

The stability of an emulsion depends not only on the surfactant type, but also on die nature of the organic phase. To characterize die oil phase, the concept of a necessary (required) HLB number is used. This number is taken to be equal to die HLB number of die surfactant which ensures the best possible emulsification of the oil. Tables of necessary HLB numbers for various oils were published in Ref 258. For example, with respect to oil-in-water emulsions, the necessary HLB number is 17 for oleic acid, 15 for toluene, 14 for xylene and cetyl alcohol, 10.5 to 12 for mineral oils, 7.5 to 8 for vegetable oils, 5 to 7 for vaseline, and 4 for paraffin. In Refs 263 and 264 the necessary HLB numbers for various oils are compared with the relative dielectric permittivity of the oil e. In the series of saturated hydrocarbons, a weak inverse dependence between the necessary HLB number and e was observed (264) e.g., e =... 

As already mentioned, one outstanding property of microemiflsions is their excellent solubilization capacity. This can be explained in terms of very good efficacy of suitable emulsifier combinations resulting in an extremely low interfacial tension between the oil and the aqueous phase. A potential application is, e.g., the solubilization of perfume oils. Perfume oils are rather polar as compared with oils that are usually used in cosmetic formulations, e.g., paraffin or ester oils. This is validated by both the dielectric coefficients and the interfacial tension between oil and aqueous phase (Table 1). In particular, the relatively low interfacial tension without addition of a sinfac-tant indicates that the perfume oil may act, at least partially, as a lipophilic cosurfactant. A similar result was found for geraniol, a doubly unsaturated monoterpene alcohol, which is one of the most used perfume chemicals [24]. It plays a role both as cosurfactant at the interface and as cosolvent in the oil phase in a system consisting of octyl monoglycoside/geraniol/cyclohex-ane/water. 

The titanosilicate version of UTD-1 has been shown to be an effective catalyst for the oxidation of alkanes, alkenes, and alcohols (77-79) by using peroxides as the oxidant. The large pores of Ti-UTD-1 readily accommodate large molecules such as 2,6-di-ferf-butylphenol (2,6-DTBP). The bulky 2,6-DTBP substrate can be converted to the corresponding quinone with activity and selectivity comparable to the mesoporous catalysts Ti-MCM-41 and Ti-HMS (80), where HMS = hexagonal mesoporous silica. Both Ti-UTD-1 and UTD-1 have also been prepared as oriented thin films via a laser ablation technique (81-85). Continuous UTD-1 membranes with the channels oriented normal to the substrate surface have been employed in a catalytic oxidation-separation process (82). At room temperature, a cyclohexene-ferf-butylhydroperoxide was passed through the membrane and epoxidation products were trapped on the down stream side. The UTD-1 membranes supported on metal frits have also been evaluated for the separation of linear paraffins and aromatics (83). In a model separation of n-hexane and toluene, enhanced permeation of the linear alkane was observed. Oriented UTD-1 films have also been evenly coated on small 3D objects such as glass and metal beads (84, 85). 

Fig. 23. Hydroformylation of liquid olefins (Cn-C12) with syngas (H2 and CO), (a) Configuration in existing commercial unit consisting of five bubble column reactors in series, (b) Improved configuration arrived at by systems approach, involving staged injection of hydrogen, (c) The yields of alcohols (desired product) and paraffins (undesired product) are compared for configurations (a) and (b).

Neither substance catalyzes hydrogen disproportionation reaction of cycloolefins. An essential difference was found in the action of these catalysts on alcohols. In the presence of vanadia, alcohols are hydro-genolyzed to the corresponding paraffins. At comparable conditions in the presence of chromia, alcohols undergo a dehydrogenation-condensation reaction with production of ketones. 

Alcohols—Water—Paraffins.— The influence of chemical relationship is well seen by comparing the properties of mixtures of the mpnhydric aliphatic alcohols with water on the one hand and with the corresponding paraffins on the other (13). 

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