Organic chemical removal methods

Cinnamaldehyde dimethylacetal is prepared by the method used to prepare the corresponding diethylacetal. A mixture of 66.0 g. (0.5 mole) of Aldrich Chemical Company, Inc.), 100 g. (1.06 mole) of trimethyl orthoformate (Eastman Organic Chemicals), 450 ml. of anhydrous methanol (J. T. Baker Chemical Company), and 0.5 g. ofp-toluenesulfonic acid monohydrate (Fisher Scientific Company) is stirred at room temperature for 24 hours. At the end of this time the alcohol is removed with a rotary evaporator and the residue is distilled to give 81-83 g. (91-93%) of cinnamaldehyde dimethylacetal, b.p. 93—96° (0.2 mm.). 

Surfactant washing is among the most promising in situ chemical treatment methods. Surfactants can improve the solvent property of the flushing water, emulsify nonsoluble organics, and enhance the removal of hydrophobic organics sorbed onto soil particles. 

Mechanical and biological methods are very effective on a large scale, and physical and chemical methods are used to overcome particular difficulties such as final sterilization, odor removal, removal of inorganic and organic chemicals and breaking oil or fat emulsions. Normally, no electrochemical processes are used [10]. On the other hand, there are particular water and effluent treatment problems where electrochemical solutions are advantageous. Indeed, electrochemistry can be a very attractive idea. It is uniquely clean because (1) electrolysis (reduction/oxidation) takes place via an inert electrode and (2) it uses a mass-free reagent so no additional chemicals are added, which would create secondary streams, which would as it is often the case with conventional procedures, need further treatment, cf. Scheme 10. 

In addition to the chemical removal of adsorbants by using acid, Pt02 is also formed by flaming the surface of a platinum electrode by a Bunsen burner - another traditional method of removing adsorbed organic materials. The cause of the oxide coating is thermal oxidation, as follows ... 

The methods that generally are used to remove volatile organic chemicals (VOCs) from biological samples for analysis are applicable to chlorobenzene. These include headspace analysis, purge-and-trap (gas stripping) collection from aqueous solutions or slurry samples, solvent extraction, and direct collection on resins. Headspace analysis offers speed, simplicity, and good reproducibility for a particular type of sample. However, partitioning of the analyte between the headspace and the sample matrix is dependent upon the nature of the matrix and must be determined separately for different kinds of matrices (Walters 1986). 

The science and technology of analytical chemistry have made steady and remarkable advances over the last 50 years. Nowhere has this been more evident than for progress on methods to analyze organic chemicals developed as pesticides and, in particular, the triazine herbicides. Methods of triazine analysis traditionally involve an extraction step in which the analyte is removed from the matrix - such as soil, water, or crop. This extract is then subjected to a clean up in various ways to isolate the analyte further from the other chemical components that are extracted. The next step is to concentrate the purified fraction to a smaller volume to allow the analyte to be detected. A small portion of this final fraction is then injected into an instrument capable of selectively detecting and quantifying the triazine in the sample. 

The imprinting of polymer supports is an exciting development in the immobilization of transition metal complexes. The process involves the copolymerization of an inorganic or an organic template into a crosslinked polymer network. In a subsequent step, the template is chemically removed leaving an imprint of molecular dimensions in the resin. Ideally, the imprint retains chemical information related to the size and shape of the template. This approach has been used to prepare chiral imprints in otherwise achiral polymer networks. The method is outlined in Scheme... 

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