Extraction and manufacture

Tin is obtained from cassiterite (Sn02) by reduction with C in a furnace (see Section 7.8), but a similar process cannot be applied to extract Pb from its sulfide ore since AfG°(CS2,g) is -l-67kJmol thermod5mamically viable processes involve reactions 13.1 or 13.2 at high temperatures. Both Sn and Pb are refined electrolytically. Recycling of Sn and Pb is highlighted in Box 13.1. 

Diamond is the hardest known substance, and apart from its commercial value as a gemstone, it has apphcations in cutting tools and abrasives (see Box 13.5). The structural differences between diamond and graphite lead to remarkable differences in physical properties (see Section 13.3) and uses. The properties of graphite that are exploited 

Activated charcoal is a finely divided form of amorphous carbon and is manufactured from organic materials (e.g. peat, wood) by heating in the presence of reagents that promote both oxidation and dehydration. Activated charcoal possesses a pore structure with a large internal surface area microporous materials exhibit pores 2nm wide, macroporous refers to activated charcoals with a pore size 50nm, and mesoporous materials fall in between these extremes. The largest internal surface areas are found for microporous materials ( 700m g ). The ability of the hydrophobic surface to adsorb small molecules is the key to the widespread applications of activated charcoal. (Comparisons should be made with the porous structures and applications of zeolites see Sections 13.9 and 26.6.) 

Early large-scale applications of activated charcoal were in gas masks in World War I. Various gas-filters including those in cooker extractors and mobile or bench-top laboratory fume-hoods contain activated charcoal filters. About 20% of the activated charcoal that is produced is consumed in the sugar industry, where it is used as a decolouring agent. Water purification uses large amounts of activated charcoal. 

The porous structure means that activated charcoal is an excellent heterogeneous catalyst, especially when impregnated with a d-block metal such as palladium. On an industrial scale, it is used, for example, in the manufacture of 

Silicon (not of high purity) is extracted from silica, Si02, by heating with C or CaCj in an electric furnace. Impure Ge 

Miscellaneous (including carbon-gnq liite conqxrsites, flexible grqtbite cloth) (58%) 

Activated charcoal has widespread apphcations hoth for gas-and liquid-phase adsorptions. Gas-phase apphcations (adsorption of gas molecules including organic vapours) usually require surface areas of 1000 to 2000m g. In addition to gas purification, activated charcoal is used in the recovery of volatile organic solvents (e.g. acetone, ethanol, toluene, chlorinated hydrocarbons) and in the paints, inks, synthetic fibres, rubbers and adhesives industries. 

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Extraction and manufacture of Zn, Pb, and Cu ores can give pollution of the environment with Cd derivatives. Cd is present also in industrial sludge and waste water. A source of Cd release is the burning of fossil fuels and the incineration of rubbish. Fertilizers can contain variable amount of Cd. Toxicological characteristics and environmental fate of Cd resemble those of Pb and Hg (see Metal Ion Toxicity). In aqueous environment Cd + shows a relative mobility it depends on pH, presence of organic molecules, and... 

Reduction in emission of toxic gases due to reusability of polymers, and improvement in extraction and manufacturing processes. 

Cradle to gate This considers all of the emissions in the extraction and manufacture of a product, including all transport-related emissions associated with the interim stages of manufacture (such as moving polymer fibres and granules). 

BENZALDEHYDE The precursor for speed. It makes up nearly 100% of bitter almond oil. Not a very popular oil with the DEA. Some hints Benzaldehyde is indispensable for the flavoring industry. It is the flavor in almond extract and synthetic benzaldehyde is used in all cherry flavorings. Also, there is currently a little loophole in the system when it comes to a product called Roasted Cassia Oil . Apparently, some manufacturers take cassia oil and run it through some sort of industrial process to change it into benzaldehyde. No one wanted to tell Strike the particulars of how this was done. But one company chemist gave me some hints (You can get really chatty with some of these guys). 

Manufacture. Cyanoacetic acid and cyanoacetates are iadustrially produced by the same route as the malonates starting from a sodium chloroacetate solution via a sodium cyanoacetate solution. Cyanoacetic acid is obtained by acidification of the sodium cyanoacetate solution followed by organic solvent extraction and evaporation. Cyanoacetates are obtained by acidification of the sodium cyanoacetate solution and subsequent esterification with the water formed being distilled off. Other processes reported ia the Hterature iavolve the oxidation of partially oxidized propionittile [107-12-0] (59). Higher esters of cyanoacetic acid are usually made through transesterification of methyl cyanoacetate ia the presence of alumiaiumisopropoxide [555-31-7] as a catalyst (60). 

Pine Oil. This oil is obtained by extraction and fractionation or by steam distillation of the wood of Pinuspalustris Mill, and other species. Most of the oil is produced ia the southeastern United States. The composition of the oil depends on the fractions chosen, but the chief constituents are terpene alcohols, mainly terpiaeol. Piae oil finds use as a germicide ia disiafectants and soaps as an ingredient ia iasecticides, deodorants, poHshes, sweepiag compounds, and catde sprays and as raw material for the manufacture of perfumery-grade terpiaeol [8000-41 -7], anethole [104-46-1], fenchone (137), and camphor (35). 

Others. The only top-fermented beer ia Scandinavia is Hvidt Lp. it has a low alcohol content (2.6% vol), a high level of extract, and is very mildly hopped. Smoke Beer is manufactured ia Germany and Denmark. It is made entirely from malt that is dried by direct beechwood fumes. In Denmark it is called Skibs Lp. (Ships Beer) and for centuries was iatended for consumption ia the Danish Navy and Marines siace it had better keeping quahties than the ordinary beers. It is top-fermented with low alcohoHc content. 

Contamination. Manufacturers of cosmetics must be careful to guard against chemical and microbial contamination. Chemical contamination, which may result from the presence of undesirable impurities in raw materials, is avoidable by adhering to rigid specifications for raw materials. Compendial specifications and pubHcations by the CTFA and other professional societies form the basis of most intracompany raw material specifications. Moreover, all packaging components must meet not only physical and design specifications but also such chemical requirements as extractables and absence of dust and similar contaminants (see Packaging, cosLffiTics and pharmaceuticals). 

Natural products Vegetable oils waxes, mineral oils plus their sulfated derivatives (including those of animal oils and fats) Sugar extraction glue manufacture cutting oils... 

Ereduc tion of a product or service must be evaluated over its entire istoiy or life cycle. This life-cycle analysis or total systems approach (Ref. 3) is crucial to identifying opportunities for improvement. As described earher, this type of evaluation identifies energy use, material inputs, and wastes generated during a products hfe from extraction and processing of raw materials to manufacture and transport of a product to the marketplace and finally to use and dispose of the produc t (Ref. 5). 

Tobacco and its alkaloids have long ceased to have any therapeutic importance, but their extensive use as insecticides and the demand for nicotine for the manufacture of nicotinic acid have stimulated interest in processes of extraction and methods of estimation. On the latter subject there is a voluminous literature, of which critical resumes have been published by various authors.Recent work on this subject has been specially concerned with (1) the development of miero- and semi-miero-methods suitable for estimating nieotine in tobacco smoke and the distribution of nieotine on sprayed garden produce, in treated soils and in tobaeeo leaves,(2) the study of conditions necessary to ensure satisfactory results in using particular processes, " and (3) methods of separation and estimation of nicotine, nomicotine and anabasine in mixtures of these bases. ) In the United States and in Russia considerable interest is being shown in the cultivation of types of tobacco rich in nicotine, in finding new industrial uses for tobacco and its alkaloids, and in possible by-products from tobacco plants such as citric and malic acids, i " Surveys of information on tobacco alkaloids have been published by Jackson, i Marion and Spath and Kuffner. ... 

The processes used in the manufacture of morphine are believed to be still based on that described by the Scottish chemist Gregory,in 1833, with improvements devised by Anderson. A description has been published by Schwyzer, who also deals with the manufactme of codeine, narcotine, cotarnine, and the commercially important morphine derivatives, diamorphine (diacetylmorphine), and ethylmorphine (morphine ethyl ether). More recently Barbier has given an account of processes, based on long experience in the preparation of alkaloids from opium. Kanewskaja has described a process for morphine, narcotine, codeine, thebaine and papaverine, and the same bases are dealt with by Chemnitius, with the addition of narceine, by Busse and Busse, and by Dott. It is of interest to note that a number of processes for the extraction and separation of opium alkaloids have been protected by patent in Soviet Russia. ... 

In order to illustrate an example of process design for the manufacture of enantiopure drug substances on an industrial SMB system, consider manufacturing 10 ton/ year of an enantiopure drug. The racemic drug by definition is a 50 50 mixture of each enantiomer (products A and B). The goal is to process enantiopure drug substances in order to obtain 99 % purity for both the extract and the raffinate. 

As described in Section 4-1. one important class of chemical reactions involves transfers of protons between chemical species. An equally important class of chemical reactions involves transfers of electrons between chemical species. These are oxidation-reduction reactions. Commonplace examples of oxidation-reduction reactions include the msting of iron, the digestion of food, and the burning of gasoline. Paper manufacture, the subject of our Box, employs oxidation-reduction chemishy to bleach wood pulp. All metals used in the chemical industry and manufacturing are extracted and purified through oxidation-reduction chemistry, and many biochemical pathways involve the transfer of electrons from one substance to another. 

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