Arenes industrial source

The Cio fraction in reformates has been considered a likely petroleum source for obtaining durene (9). However, there are 28 kinds of isomeric arenes in the fraction, and the durene content is only 5-9%. Therefore, the isolation of durene from such a complicated mixture is inefficient, and some complicated techniques are required for it. In contrast, 1,2,4-trimethyl-benzene (pseudocumene) can be easily isolated simply by the distillation of the Cg fraction of the reformates, and a high-purity pseudocumene has been produced on an industrial scale. 

This is confusing. Why don t risk assessors simply decide what level of exposure is safe for each chemical, and risk managers simply put into effect mechanisms to ensure that industry reaches the safe level Why should different sources of risk be treated differently Why apply a no risk standard to certain substances (e.g., those intentionally introduced into food, such as aspartame) and an apparently more lenient risk-henefit standard to unwanted contaminants of food such as PCBs, methylmercury, and aflatoxins (which the FDA applies under another section of food law) Why allow technological limitations to influence any decision about health What is this risk-henefit balancing nonsense Aren t some of these statutes simply sophisticated mechanisms to allow polluters to expose people to risk ... 

Reactions of or Hj sources (e.g., Zn-HCl) with alkenes, alkynes, arenes, ketones, nitriles, carboxylic acids and esters are used industrially for C—H bond formation . Heterogeneous reaction catalysts (e.g., Ni, Pt, Pd, Fe, Ni-Cu) are used, e.g. ... 

Calix[9]arenes Bew and Shartna reported a SnCLr-promoted synthesis of p-tert-butylcalix[9]arene C[9] (36% yield) using 5-trioxane as formaldehyde source in CH2CI2 as the solvent [16]. Besides to C[9], a good amount of p-ter/-butylcalix[8] arene (58 %) was also obtained. Recently, Bonnamour and coworkers [16] have reported a large scale synthesis of p-/er/-butylcalixarenes C[7] and C[9]. The procedure, involves the use of 1,2-dichloroethane, p-/ert-butylphenol, TsOH and s-trioxane, and it is performed on a semi-industrial scale reactor. From 1,000 g of p-ferf-butylphenol it is possible to obtain 96 g C[7] and 25 g of C[9] with a simplified workup procedure. The cost of two macrocycles from this synthesis are very inexpensive (15 /g and 60 /g, respectively) [16]. 

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