Substances from oil

You saw in Chapter 6 that crude oil is made up of a complex mixture of hydrocarbon compounds. This mixture is a very important raw material in the organic chemical industry. Our world would be a very different place without these substances. Can you imagine life without the substances from oil and natural gas There would be no oil-based fuels, such as petrol and diesel, and the chemical industry, particularly the plastics industry, would also suffer since substances extracted from oil are used as raw materials for many plastics. 

McCalla TM, Haskins FA (1964) Phytotoxic substances from oil micro-organism and crop residues. Bact Rev 28 181-207... 

Nature Identical Flavor Matenal A flavor ingredient obtained by synthesis, or isolated from natural products through chemical processes, chemically identical to the substance present in a natural product and intended for human consumption either processed or not eg, citral obtained by chemical synthesis or from oil of lemongrass through a bisulfite addition compound. 

Ammonium nitrate is normally classified as an oxidizing agent. The pure salt is not classed as an explosive because it is difficult to detonate. Spark, flame, or friction do not cause detonation, and ammonium nitrate is relatively insensitive to shock. However, a variety of substances, such as chloride and oil, are known to sensitize the material, so manufacturers strive to eliminate such substances from their processes. 

Solvent Extraction. Extraction processes, used for separating one substance from another, are commonly employed in the pharmaceutical and food processing industries. Oilseed extraction is the most widely used extraction process on the basis of tons processed. Extraction-grade hexane is the solvent used to extract soybeans, cottonseed, com, peanuts, and other oilseeds to produce edible oils and meal used for animal feed supplements. Tight specifications require a narrow distillation range to minimize solvent losses as well as an extremely low benzene content. The specification also has a composition requirement, which is very unusual for a hydrocarbon, where the different components of the solvent must be present within certain ranges (see Exthaction). 

In addition to films that originate at least in part in the corroding metal, there are others that originate in the corrosive solution. These include various salts, such as carbonates and sulfates, which may be precipitated from heated solutions, and insoluble compounds, such as beer stone, which form on metal surfaces in contac t with certain specific products. In addition, there are films of oil and grease that may protect a material from direct contact with corrosive substances. Such oil films may be apphed intentionally or may occur naturally, as in the case of metals submerged in sewage or equipment used for the processing of oily substances. 

The same compound, linalol, is the parent substance of oil of lavender. The study of the progressive development of this oil in the plant tissues was carried out on three samples which were distilPd at intervals of a fortnight, the first from flowers in the budding stage, the second from the fully flowering plants, and the third from the plants with the flowers faded. The essential oils thus obtained had the following characters — ... 

A sesquiterpene alcohol, CjgHjgO, has been extracted by means of phthalic anhydride from oil of opoponax resin. It distils at 135° to 137° in vactu) (2 imm.), and yields a crystalline phenylurethane. But as, in spite of repeated crystallisations, it could not be obtained of constant melting-point, it is probable that the substance is a mixture of two or more alcohols. 

This acid, CgHj. CH COOH, is a sweet-smelling substance, especially recommended for sweetening soap perfumes. It occurs in neroli oil, and has a sweet honey-like odour. It is formed by converting toluene into benzyl chloride which is converted into benzyl cyanide, which is digested with dilute sulphuric acid, and so converted into phenyl-acetic acid. It is a crystalline body, melting at 76° to 76 5° and Iwiling at 266°. It has been isolated from oil of neroli. 

Safrole, a substance isolated from oil of sassafras, is used as a perfumery agent. Propose a synthesis of safrole from catechol (1,2-benzenediol). 

Methyl-5-hepten-2-one is a constituent of lemongrass oil. How could you synthesize this substance from methyl 4-oxopentanoate ... 

Essential oils are known to have detrimental effects on plants. The inhibitory components have not been identified, but both alde-hydic (benzol-, citrol-, cinnamal-aldehyde) and phenolic (thymol, carvacol, apiol, safrol) constituents are suspected. Muller et al. (104) demonstrated that volatile toxic materials localized in the leaves of Salvia leucophylla, Salvia apiana, and Arthemisia californica inhibited the root growth of cucumber and oat seedlings. They speculated that in the field, toxic substances from the leaves of these plants might be deposited in dew droplets on adjacent annual plants. In a subsequent paper, Muller and Muller (105) reported that the leaves of S. leucophylla contained several volatile terpenes, and growth inhibition was attributed to camphor and cineole. 

The dense fluid that exists above the critical temperature and pressure of a substance is called a supercritical fluid. It may be so dense that, although it is formally a gas, it is as dense as a liquid phase and can act as a solvent for liquids and solids. Supercritical carbon dioxide, for instance, can dissolve organic compounds. It is used to remove caffeine from coffee beans, to separate drugs from biological fluids for later analysis, and to extract perfumes from flowers and phytochemicals from herbs. The use of supercritical carbon dioxide avoids contamination with potentially harmful solvents and allows rapid extraction on account of the high mobility of the molecules through the fluid. Supercritical hydrocarbons are used to dissolve coal and separate it from ash, and they have been proposed for extracting oil from oil-rich tar sands. 

In cases where the aromatic C—C bonds were attacked and various water-soluble substances capable of extraction from oil were formed, a reduction in the total heating value of the fuel was consequently observed [137], Hence, such reaction was categorized as an industrially unacceptable reaction, since that pathway not only destroyed the carbon skeleton reducing the energy content of fuel but also converted DBT to 3-hydroxy-2-formylbenzothiophene without actually desulfurizing it to HBP. 

Leoni [366] observed that in the extraction preconcentration of organochlo-rine insecticides and PCB s from surface and coastal waters in the presence of other pollutants such as oil, surface active substances, etc., the results obtained with an absorption column of Tenax-Celite are equivalent to those obtained with the continuous liquid-liquid extraction technique. For non-saline waters that contain solids in suspension that absorb pesticides, it may be necessary to filter the water before extraction with Tenax and then to extract the suspended solids separately. Analyses of river and estuarine sea waters, filtered before extraction, showed the effectiveness of Tenax, and the extracts obtained for pesticide analysis prove to be much less contaminated by interfering substances than corresponding extracts obtained by the liquid-liquid technique. Leoni et al. [365] showed that for the extraction of organic micro pollutants such as pesticides and aromatic polycyclic hydrocarbons from waters, the recoveries of these substances from unpolluted waters (mineral and potable waters) when added at the level of 1 xg/l averaged 90%. 

Just as oil, natural gas is also categorised as conventional and unconventional. Unlike crude oil, however, natural gas deposits are normally classified according to the economic or technical approach, i.e., all occurrences that are currently extract-able under economic conditions are considered conventional, whereas the rest are termed unconventional. Conventional natural gas includes non-associated gas from gas reservoirs in which there is little or no crude oil, as well as associated gas , which is produced from oil wells the latter can exist separately from oil in the formation (free gas, also known as cap gas, as it lies above the oil), or dissolved in the crude oil (dissolved gas). Unconventional gas is the same substance as conventional natural gas, and only the reservoir characteristics are different and make it usually more difficult to produce. Unconventional gas comprises natural gas from coal (also known as coal-bed methane), tight gas, gas in aquifers and gas hydrates (see Fig. 3.17). It is important to mention in this context so-called stranded gas , a term which is applied to occurrences whose extraction would be technically feasible, but which are located in remote areas that at the moment cannot (yet) be economically developed (see Section 3.4.3.1). 

You should use a minimum amount of solvent, and if necessary add more through the condenser (do not use too much and do not let the flask (G) become dry at any time). When the extraction is complete, dismantle the apparatus and crystallize the substance from the solution in the flask, or separate the resulting oil, etc. 

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