Chemical structure aromatics

A common method of classification for petroleum is the PONA system (PONA is an acronym for paraffins, olefins, naphthenes, and aromatics). Paraffins are straight-chain or branched hydrocarbons in which there are no double or triple bonds between carbon atoms. Olefins are similar to paraffins, but they contain at least one multiple bond in their chemical structure. Naphthenes are saturated hydrocarbons, just like paraffins, but they incorporate a ring of carbon atoms into their chemical structure. Aromatics contain a benzene ring in their structure. 

Chemical structure. Aromatic or aliphatic compounds alcohols, ketones, esters, ethers, etc. 

As in the case of density or specific gravity, the refractive index, n, for hydrocarbons varies in relation to their chemical structures. The value of n follows the order n paraffins < n naphthenes < n aromatics and it increases with molecular weight. 

The smoke point corresponds to the maximum possible flame height (without smoke formation) from a standardized lamp (NF M 07-028). The values commonly obtained are between 10 and 40 mm and the specifications for TRO fix a minimum threshold of 25 mm. The smoke point is directly linked to the chemical structure of the fuel it is high, therefore satisfactory, for the linear paraffins, lower for branched paraffins and much lower still for naphthenes and aromatics. 

The organic chemical structural types believed to be characteristic of coals include complex polycyclic aromatic ring systems with connecting bridges and varied oxygen-, sulfur-, and nitrogen-containing functionalities. 

A substantial portion of fhe gas and vapors emitted to the atmosphere in appreciable quantity from anthropogenic sources tends to be relatively simple in chemical structure carbon dioxide, carbon monoxide, sulfur dioxide, and nitric oxide from combustion processes hydrogen sulfide, ammonia, hydrogen chloride, and hydrogen fluoride from industrial processes. The solvents and gasoline fractions that evaporate are alkanes, alkenes, and aromatics with relatively simple structures. In addition, more complex... 

J. H. Ridd, Acc. Chem. Res. 4 248 (1971) J. H. Ridd, in Studies on Chemical Structure and Reactivity, J. H. Ridd, ed., John Wiley Sons, New Vbik, 1966, Chapter 7 J. G. Hoggett, R. B. Moodie, J. R. Penton, and K. Schofield, Nitration and Aromatic Reactivity, Cambridge University Press, Cambridge, 1971 K. Schofield, Aromatic Nitration, Cambridge University Press, Cambridge, 1980 G. A. Olah, R. Malhotra, and S. C. Narang, Nitration, Methods and Mechanisms, VCH Publishers, New i)rk, 1989. 

Table 4 shows that the substrates usually involved in the reaction with polydichlorophosphazene belong to the categories of aliphatic or aromatic compounds containing in their own chemical structure free -OH and/or -NH2 functionalities, which can be easily found on the market in great abundance and at cheap prices. 

Kami H, T Watanabe, S Takemura, Y Kameda, T Hirayama (2000) isolation and chemical-structural identification of a novel aromatic amine mutagen in an ozonized solution of m-phenylenediamine. Chem Res Toxicol 13 165-169. 

Reineke W, H-J Knackmuss (1978) Chemical structure and biodegradability of halogenated aromatic compounds. Substituent effects on 1,2-dioxygenation of benzoic acid. Biochim Biophys Acta 542 412-423. 

The DSC and TGA plots of the oxidized polymer (VIII) showed that the Tm is 130°C and the weight loss of 20% and 80% was observed at 455°C and 600°C, respectively, compared to 400° and 482°C for the original polymer VII indicating the oxidized polymer was more stable to heat. This observation was consistent with the chemical structure of the oxidized polymer, which consisted of a repeating aromatic pyrrole structure and, therefore, should be more thermodynamically stable. The thermal data of the polymers are tabulated in Table II. 

Polyamides are macromolecules with acidamide units —CONH—, where the chemical structure of the other parts of the monomers can be aliphatic and/or aromatic. Similar structures are found in nature, for example, polypeptides. Although in principle a large number of potential polyamide structures can be produced, only a few polyamides are produced in industrial scale. 

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