Synthetic chemicals

Synthetics. The lack of spice products to satisfy demand and the wide variation in price and availabihty have caused the manufacture of selected synthetics, chemically identical to the component in the natural spice, to replace the vital components of some spices. However, synthetic organic chemistry is not yet able to manufacture economically the many homologous piperine [94-62-2] components in black pepper or those capsaicin [404-86-4] amides in... 

Wintergreen Oil. Water distillation of the leaves of Gaultheriaprocumbens L. yields an oil which consists of essentially one chemical constituent, methyl saUcylate. Because of this, the oil has been almost totally replaced by the synthetic chemical. Natural oil of wintergreen [68917-75-9] is a pale yellow to pinkish colored mobile Hquid of intensely sweet-aromatic odor and flavor. The oil or its synthetic replacement find extensive use in pharmaceutical preparations, candy, toothpaste, industrial products, and in rootbeer flavor. In perfumery, it is used in fougnre or forest-type fragrances. 

Trimesic acid is also referred to as 5-carboxyisophthahc acid [554-95-0] trimesinic acid, or trimesitinic acid. It is a smaH-volume, synthetic chemical and is sold commercially. Traces of trimesic acid as well as other aromatic carboxyUc acids with three or more carboxyUc acid groups are found in lignite (137), and when various types of coals or coal components such as brown coal, asphaltene, or coal-tar pitch are oxidized. 

Any radioactive nucUde or isotope of an element can be used as a radioactive tracer, eg, chromium-51 [14392-02-0] cobalt-60 [10198-40-0] tin-110 [15700-33-1] and mercury-203 [13982-78-0],hut the preponderance ofuse has been for carbon-14 [14762-75-5],hydj ogen-3 [10028-17-8] (tritium), sulfur-35 [15117-53-0], phosphoms-32, and iodine-125 [14158-31 -7]. More recendy phosphoms-33 has become available and is used to replace sulfur-35 and phosphoms-32 in many appUcations. By far the greater number of radioactive tracers produced are based on carbon-14 and hydrogen-3 because carbon and hydrogen exist in a large majority of the known natural and synthetic chemical compounds. 

Syntheses of radioactive tracers involve all of the classical biochemical and synthetic chemical reactions used in the synthesis of nonradio active chemicals. There are, however, specialized techniques and considerations required for the safe handling of radioactive chemicals, strategic synthetic considerations in terms of their relatively high cost, and synthesis scale constraints governed by specific activity requirements. 

Synthetic chemical approaches to the preparation of carbon-14 labeled materials iavolve a number of basic building blocks prepared from barium [ CJ-carbonate (2). These are carbon [ C]-dioxide [ CJ-acetjlene [U— C]-ben2ene, where U = uniformly labeled [1- and 2- C]-sodium acetate, [ C]-methyl iodide, [ C]-methanol, sodium [ C]-cyanide, and [ CJ-urea. Many compHcated radiotracers are synthesized from these materials. Some examples are [l- C]-8,ll,14-eicosatrienoic acid [3435-80-1] inoxn. [ CJ-carbon dioxide, [ting-U— C]-phenyhsothiocyanate [77590-93-3] ftom [ " CJ-acetjlene, [7- " C]-norepinephrine [18155-53-8] from [l- " C]-acetic acid, [4- " C]-cholesterol [1976-77-8] from [ " CJ-methyl iodide, [l- " C]-glucose [4005-41-8] from sodium [ " C]-cyanide, and [2- " C]-uracil [626-07-3] [27017-27-2] from [ " C]-urea. All syntheses of the basic radioactive building blocks have been described (4). 

Quality. The plant operated by Synthetic Chemicals Ltd. operates within a quaUty management system, which complies with British Standard (BS) 5750 and ISO 9001, Part 1. 

Sales of thiophene in the 1990s amount to hundreds of metric tons per year. SuppHes are available worldwide from Synthetic Chemicals Ltd. (SCL) in the United Kingdom and Elf-Atochem SA in France. There is currendy no U.S. producer of thiophene or the principal thiophene derivatives. At these levels of demand, material is shipped in 200-hter dmms and in bulk quantities. Market price is dependent on the level of off-take. 3-Methylthiophene is also available from SCL, but demand is low and even lower in the case of 2-methylthiophene lower production and lower market demand have led to higher prices for these derivatives. 

Technical data. Synthetic Chemicals, Ltd., Huntingdon Research Centre Reports, July 1987. 

Technical data. Synthetic Chemicals Ltd., Binnie Environmental Report ENV161, 1994. 

Natural and synthetic chemicals affect every phase of our daily Hves ia both good and noxious manners. The noxious effects of certain substances have been appreciated siace the time of the ancient Greeks. However, it was not until the sixteenth century that certain principles of toxicology became formulated as a result of the thoughts of Philippus Aureolus Theophrastus Bombastus von Hohenheim-Paracelsus (1493—1541). Among a variety of other achievements, he embodied the basis for contemporary appreciation of dose—response relationships ia his often paraphrased dictum "Only the dose makes a poison."... 

Aerobic, Anaerobic, and Combined Systems. The vast majority of in situ bioremediations ate conducted under aerobic conditions because most organics can be degraded aerobically and more rapidly than under anaerobic conditions. Some synthetic chemicals are highly resistant to aerobic biodegradation, such as highly oxidized, chlorinated hydrocarbons and polynuclear aromatic hydrocarbons (PAHs). Examples of such compounds are tetrachloroethylene, TCE, benzo(a)pyrene [50-32-8] PCBs, and pesticides. 

PCBS (polychlorinated biphenyls) Toxic synthetic chemicals with excellent heat resistance and low electrical conductivity properties. Now little used but considerable quantities remain in old electrical equipment. Produces dioxins and polychlorinated dibenzo-furans when burned below 1200°C. PCBs are toxic and bio-accumulative. 

What has become an even greater concern in recent years is the phenomenon known as multiple chemical sensitivity disorder triggered by exposures to many chemicals in the environment. Synthetic chemicals are all around us. They are in the products we use, in the clothes we wear, in the food we eat, in the air we breathe at work. Because chemicals are everywhere in the environment, it is not possible to escape exposure. For this reason many people have become sensitized to the chemicals around them. In fact, it is estimated that 15% of the population has become sensitized to common household and commercial products. For some people the sensitization is not too serious a problem. They may have what appears to be a minor allergy to one or more chemicals. Other people are much more seriously affected. They may feel tired all the time, and suffer from mental confusion, breathing problems, sore muscles, and a weakened immune system. Such people suffer from a condition known as Multiple Chemical Sensitivity (MCS). 

There are even receptors that are known to become activated only due to interaction with a synthetic chemical, and no physiological agonist for such a receptor has been characterized. A model receptor in this class is the so-called Ah receptor complex that becomes activated subsequent to its exposure to 2,3,7,8-tetrachlorodibenzo-p-dioxiu (TCDD). Activation of the. Ah receptor... 

Acknowledgment The authors wish to express their gratitude to Dr. J. Edwards of Syntex Research who provided the experimental procedure utilizing silver carbonate on Celite. We are also indebted to the Synthetic Chemical Research Department of Merck Sharp Dohme Research Laboratories for providing time to complete this review and also to Miss Joanna Mohr for her patience and care in preparing the manuscript. 

Nippon Synthetic Chemical Industiy (Japan) Schweizerhall (Switzerland)... 

Nippon Synthetic Chemical Industry (Japan) Panreac Quemica (Spain)... 

Nippon Synthetic Chemical hidustry Co. Ltd. (Nippon Gohsei), 187... 

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