Aromatic-to-aliphatic ratios

Aromatic positions, deuterium-hydrogen exchange reaction of tetralin-di2 and diphenylmethane, I62t,l63t Aromatic stretching, FTIR of vitrinite, 103-12 Aromatic-to-aliphatic ratios, carbon-13 NMR, 80-95 Aromaticity, 73... 

If infrared and ultraviolet spectra are available, they should be inspected for preliminary clues about the functional groups and conjugation that might be present. A fairly superficial survey of the JH and 13C spectra should enable you to assess such factors as the degree and kind of symmetry in the molecule the ratio of aromatic to aliphatic carbons the number of methyl, methylene, methine and quaternary carbons and the number of exchangeable protons. The next stage is a detailed study of the one-dimensional or COSY spectrum ... 

Figure 4. Change in the ratio of aromatic-to-aliphatic C in freshwater DOM exposed to solar radiation. Dark bars are 0.2 filtered and reverse osmosis concentrated samples collected from Lake Lacawac, Pennsylvania, USA during 1999. Stippled bars are results from sunlight exposure of bog DOM during 1998. From Osburn [158].

The changes in this ratio upon oxidation were studied by Haghseresht and co-workers [279]. They found that with an increase in severity of oxidation conditions, the ratio of aromatic to aliphatic carbon increased. Using that observation, the degree of the oxidation in the carbon precursors can be evaluated. 

Most hydroxy-terminated polyesters are made by coesterifying two polyols (a diol and a triol) and two diacids (an aliphatic dibasic acid and an aromatic dicarboxylic acid or its anhydride). The ratio of moles of dibasic acid to polyol must be less than 1 so as to give terminal hydroxyl groups and avoid gelation. Molecular weight is controlled by this ratio the smaller the ratio, the lower the molecular weight. The molecular weight distribution Mn, and /n are all controlled by the diol-to-triol ratio. The ratio of aromatic to aliphatic dibasic acids controls Tg of the resin. 

The ratio of aromatic to aliphatic hydrogen depends mainly on the source of the starting material. The hydrogen aromaticity (ratio of aromatic to total hydrogen atoms) varies... 

As has been noted earlier, the solvent usually has little effect on free-radical substitutions in contrast to ionic ones indeed, reactions in solution are often quite similar in character to those in the gas phase, where there is no solvent at all. However, in certain cases the solvent can make an appreciable difference. Chlorination of 2,3-dimethylbutane in aliphatic solvents gave 60% (CH3)2CHCH-(CH3)CH2C1 and 40% (CH3)2CHCC1(CH3)2, while in aromatic solvents the ratio became 10 90. This result is attributed to complex formation between the... 

The nmr analyses of the bottoms products given in Table IV show the material to have a large aliphatic content. The aromatic/aliphatic ratios of the fractions are higher than for the whole coal because of the presence of combined phenol reaction with Tetralin reduces these ratios considerably, presumably by transfer of much of this material to the solvent-range product, but some of it must remain in the bottoms as the aromatic/aliphatic ratio of the composite bottoms product from the fractions is higher than that from the whole coal. It was not possible to calculate the contribution that the diluents, excess solvent and combined phenol, made to the aromatic H, but the large monoaromatic content of the bottoms product must be due, in part, to these. 

Isocyanate Crosslinkers. A wide variety of both aromatic and aliphatic Isocyanate crosslinkers are used in coatings (4). Aliphatic isocyanates are used when external durability is required. The isocyanate crosslinker studied in this work is the biuret of hexamethylene diisocyanate (Figure 1). Although resins based on triisocyanurates have been claimed to be superior in durability (,22.) > biuret based triisocyanates are more commonly used. Urethane coatings are generally formulated with a ratio of isocyanate to hydroxy of around 1 1. 

For the sake of brevity, the yield data for all the individual components are not reported in Table II and subsequent tables. The yield of unreported components (usually Cs-i- olefins and naphthenes) can be calculated as 100 minus percentage yield of the reported components. Results shown in Table ll indicate that thermally treated ZSM-5 produced a high yield of Ce to Ce aromatics, Cs and C4 hydrocarbons. Steam treatment of ZSM-5 reduced cracking activity and increased the selectivity for Cs to C aliphatics at the expense of aromatics. The olefin to paraffin ratio in the product also increased upon steaming. 

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