Hydrocarbons Organic compounds that unsaturated

Aromatic, olefinic, and acetylenic hydrocarbons, but especially saturated hydrocarbons belong to persistent pollutants difficult to eliminate from the troposphere. The only exceptions are some aromatic compounds that undergo direct photodegradation in result of solar irradiation. Alkanes are undoubtedly much less reactive than other organic compounds including unsaturated hydrocarbons, surely because they are more completely saturated and their activation involves cleavage of the relatively strong C—H bond (s = 415 kJ). 

The alkane, alkene, alkyne, and aromatic families are members of a larger grouping referred to as hydrocarbons. Hydrocarbons are organic compounds that contain only carbon and hydrogen. The alkenes, alkynes, and aromatics are unsaturated hydrocarbons since they contain carbon-carbon multiple bonds. The alkanes are referred to as saturated hydrocarbons since they do not contain carbon-carbon multiple bonds, only carbon-carbon single bonds. 

The principal mbbers, eg, natural, SBR, or polybutadiene, being unsaturated hydrocarbons, are subjected to sulfur vulcanization, and this process requires certain ingredients in the mbber compound, besides the sulfur, eg, accelerator, zinc oxide, and stearic acid. Accelerators are catalysts that accelerate the cross-linking reaction so that reaction time drops from many hours to perhaps 20—30 min at about 130°C. There are a large number of such accelerators, mainly organic compounds, but the most popular are of the thiol or disulfide type. Zinc oxide is required to activate the accelerator by forming zinc salts. Stearic acid, or another fatty acid, helps to solubilize the zinc compounds. 

In contrast to the other large cats, the urine of the cheetah, A. jubatus, is practically odorless to the human nose. An analysis of the organic material from cheetah urine showed that diglycerides, triglycerides, and free sterols are possibly present in the urine and that it contains some of the C2-C8 fatty acids [95], while aldehydes and ketones that are prominent in tiger and leopard urine [96] are absent from cheetah urine. A recent study [97] of the chemical composition of the urine of cheetah in their natural habitat and in captivity has shown that volatile hydrocarbons, aldehydes, saturated and unsaturated cyclic and acyclic ketones, carboxylic acids and short-chain ethers are compound classes represented in minute quantities by more than one member in the urine of this animal. Traces of 2-acetylfuran, acetaldehyde diethyl acetal, ethyl acetate, dimethyl sulfone, formanilide, and larger quantities of urea and elemental sulfur were also present in the urine of this animal. Sulfur was found in all the urine samples collected from male cheetah in captivity in South Africa and from wild cheetah in Namibia. Only one organosulfur compound, dimethyl disulfide, is present in the urine at such a low concentration that it is not detectable by humans [97]. 

As discussed elsewhere (212), the one-electron oxidation or reduction of, e.g., unsaturated hydrocarbons or other electroactive organic compounds and ions [Eqs. (37a)-(37d)] creates radical cations, radical anions, or radicals with an energy content, which surmounts that of the original substrate... 

O aikene an unsaturated hydrocarbon that contains at least one double bond between two of the carbon atoms in the chain the simplest aikene is ethene, CjH4 O homologous series a family of organic compounds with similar chemical properties as they contain the same functional group alkenes, alcohols, for instance O isomers molecules with the same molecular formula but different stnictural formulae O substitution reaction a reaction in which one or more hydrogen atoms in a hydrocarbon are replaced by atoms of another element... 

One remarkable group of homogeneous CO reactions 1 that of the conversions with unsaturated hydrocarbons using alkynes. alkcnes or dienes as the adducts, lactones, acids or esters are produced. The two most efficient catalyst metals are rhodium and palladium. This part of CO chemistry is a very fascinating one, because carbon dioxide is fixed in the organic compounds, through the formation of a new carbon-carbon bond. 

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