Alkenes terpene hydrocarbons

Violent explosions which occurred at —100 to —180°C in ammonia synthesis gas units were traced to the formation of explosive addition products of dienes and oxides of nitrogen, produced from interaction of nitrogen oxide and oxygen. Laboratory experiments showed that the addition products from 1,3-butadiene or cyclopentadiene formed rapidly at about — 150°C, and ignited or exploded on warming to —35 to — 15°C. The unconjugated propadiene, and alkenes or acetylene reacted slowly and the products did not ignite until +30 to +50°C [1], This type of derivative ( pseudo-nitrosite ) was formerly used (Wallach) to characterise terpene hydrocarbons. Further comments were made later [2],... 

Alkenes Unsaturated hydrocarbon compounds with the general formula CnH2n in the simplest cases. They contain double covalent bonds. Terpenes, an important constituent of essential oils, are alkenes. 

Other hydrocarbons reported to be present in olive oil are C14-C30 n-alkanes, some n-alkenes, and terpene hydrocarbons—mainly a-farnesene. The level of these hydrocarbons is approximately 150-200 mg/kg (Lanzon et al. 1994). There is also a limited presence of aromatic polycyclic hydrocarbons (such as naphthalene and phenanthrene) but it is not quite clear to what extent they are natural constituents or contaminants (Tiscomia et al. 1982, Moret et al. 1997). 

Hydrocarbons, compounds of carbon and hydrogen, are stmcturally classified as aromatic and aliphatic the latter includes alkanes (paraffins), alkenes (olefins), alkynes (acetylenes), and cycloparaffins. An example of a low molecular weight paraffin is methane [74-82-8], of an olefin, ethylene [74-85-1], of a cycloparaffin, cyclopentane [287-92-3], and of an aromatic, benzene [71-43-2]. Cmde petroleum oils [8002-05-9], which span a range of molecular weights of these compounds, excluding the very reactive olefins, have been classified according to their content as paraffinic, cycloparaffinic (naphthenic), or aromatic. The hydrocarbon class of terpenes is not discussed here. Terpenes, such as turpentine [8006-64-2] are found widely distributed in plants, and consist of repeating isoprene [78-79-5] units (see Isoprene Terpenoids). 

Explicit mechanisms attempt to include all nonmethane hydrocarbons believed present in the system with an explicit representation of their known chemical reactions. Atmospheric simulation experiments with controlled NMHC concentrations can be used to develop explicit mechanisms. Examples of these are Leone and Seinfeld (164), Hough (165) and Atkinson et al (169). Rate constants for homogeneous (gas-phase) reactions and photolytic processes are fairly well established for many NMHC. Most of the lower alkanes and alkenes have been extensively studied, and the reactions of the higher family members, although little studied, should be comparable to the lower members of the family. Terpenes and aromatic hydrocarbons, on the other hand, are still inadequately understood, in spite of considerable experimental effort. Parameterization of NMHC chemistry results when NMHC s known to be present in the atmosphere are not explicitly incorporated into the mechanism, but rather are assigned to augment the concentration of NMHC s of similar chemical nature which the... 

Most oils contain low levels of saturated and unsaturated hydrocarbons. In olive oil, the unsaturated hydrocarbon squalene can constitute up to 40% of the unsaponifiable fraction (Boskou, 1996). Other hydrocarbons commonly present in olive oil are straight chain alkanes and alkenes with 13 to 35 carbon atoms, along with very low amounts of branched chain hydrocarbons. Variations are found between different olive varieties but the main hydrocarbons are those with 23, 25, 27 and 29 carbon atoms (Guinda et al., 1996). Olive oil can clearly be differentiated from other vegetable oils on the basis of hydrocarbon components, and levels of 2.6% crude rapeseed oil or crude sunflower oil can be detected by hydrocarbon analysis (Webster et al., 1999). Terpenes have been identified in the volatile fraction of crude sunflower oil (Bocci and Frega, 1996). 

Looked at as a polymer, rubber is made up of C5 units joined together by C-C bonds. We should naturally expect to make a hydrocarbon polymer from alkenes, so if we separate these C5 units we find that they are dienes rather than simple alkenes. if you have read Chapter 51, they might be familiar to you as the isoprene units from which terpenes were originally supposed to be made. 

Hundreds of VOCs are found in a typical nonindustrial indoor environment. Many of these compounds are aromatic hydrocarbons, alkenes, alcohols, aliphatic hydrocarbons, aldehydes, ketones, esters, glycols, glycolethers, halocarbons, cycloalkanes and terpenes [2] but amines hke nicotine, pyridine, 2-pi-coline, 3-ethenylpyridine and myosmine are also widespread, especially in smoking microenvironments [3]. Moreover, low molecular weight carboxylic acids, siloxanes, alkenes, cycloalkenes and Freon 11 are frequently encountered in typical nonindustrial indoor air [1]. 

Volatile emissions from vegetation include hydrocarbons other than isoprene and terpenes. Altshuller (1983) has compiled emission data available to him [mainly from Zimmerman (1979a,b)]. The emissions contained C2-C6 alkanes, various alkenes, and C6-C12 volatile organic compounds. Practically every deciduous plant and all the grasses studied emitted alkanes with ethane and propane dominating the mixture. Twenty to 50% of total hydrocarbon emissions, on average, consisted of alkanes. 

The addition takes place according to Markownikoff s rule. The addition of carbo lic acida to the double bonds of isobutylene and trimethyl-ethylene gives tertiary esters. A true equilibrium independent of sulfuric acid concentrations is established in the exothermic reaction. The addition does not go well with ethylene, but goes well with many of the higher alkenes, particularly with some of the terpenes. To avoid the polymerizing effects of sulfuric acid, various other catalysts, such as sulfonic acids, triethylamine, hydrofluoric acid, boron trifluoride, and cuprous chloride have been used. The addition may take place at room temperature or higher and is aided by pressure. The vapors of the acid and hydrocarbon may be passed over catalysts, such as activated carbon, heteropoly acids, or metal phosphates. ... 

Grignard also did extensive work in the areas of the terpenes, quantitative ozonolysis of alkenes, aldol reactions, catalytic hydrogenation, and dehydrogenation and cracking of hydrocarbons. ... 

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