Chlorination and oxidation

Chemicals Chlorination and oxidation Steam injection Acid and base dilution Fast reactions... 

In chlorinations either a substitution or an addition process can occur with the ultimate reaction pathway(s) determined by a combination of factors, which include the reaction conditions, the positions and natures of any substituents present, and the catalyst used. Uncatalyzed chlorination of benzothiadiazole is an exothermic reaction that gives rise to a mixture of isomeric tetrachloro addition products. These are converted in basic medium into 4,7-dichloro-2,1,3-benzothiadiazole (70RCR923). When an iron(III) catalyst is present 4- and 7-chloro substitution becomes the dominant process. Chlorination of a number of 4-substituted 2,1,3-benzothiadiazoles (43) using an oxidative process gave a combination of chlorinated and oxidized products. The 4-hydroxy, 4-amino-, 4-methyl-amino, and 4-acetoxy derivatives of 43 all formed the chloroquinones (44) (40-61% yields). With the 4-aIkoxy substrates both 44 and some 5,7-dichlorinated product were obtained (88CHE96). 

The analysis methods are national in scope and address emissions from a wide variety of industrial and community source types. The materials reviewed are of widely disparate natures. They include metals, and bulk and trace hydrocarbons, including chlorinated and oxide derivatives of hydrocarbons. The analyses are intended to be preliminary screening analyses for use in scoping and prioritizing regulatory attention to toxic exposures from the chemicals studied. 

Usually, N-sulfinyl compounds (59) behave as thionyl transfer reagents, similar to, but milder than, thionyl chloride. For example, o-diamines with A-sulfinylbenzeneamine (59 R = Ph) afford fused 1,2,5-thiadiazoles, as in Scheme 8a.77 The advantage of using Af-sulfinyl compounds, rather than thionyl chloride itself, is that concomitant chlorinations and oxidations are avoided. This is of particular importance in the synthesis of 2,1-benzisothia-zoles (Section V,B,6). Singerman s reagent, N-sulfinylmethanesulfonamide (60) is especially valuable 78 it was used very successfully in the synthesis of a series of benzobis(isothiazoles).79... 

ICON [Integrated chlorination and oxidation] An improved version of the Chloride Process for making titanium dioxide pigment. It operates at above atmospheric pressure and is claimed to be cheaper to build. Chlorine from the oxidation section, under pressure, is introduced directly to the chlorinator. Developed by Tioxide Group, and first operated at its plant at Greatham, UK, in 1990. 

PS is soluble in aromatic hydrocarbon solvents and is resistant to aqueous solutions of nonoxidizing acids, alkalis, and salts. It is attacked by chlorine and oxidizing acids, such as 25% nitric and 95% sulfuric adds. In the absence of flame retardants, this aromatic hydrocarbon polymer burns readily and produces considerable amounts of black smoke. The latter is due to the formation of highly colored cyclic byproducts as the PS is burned. 

Since nitrides have lower heats of formation than oxides, the reaction between chlorine and nitrides will be more complete than between chlorine and oxides. Nitrides react with chlorine to give chlorides and nitrogen. Chlorine, in fact, can displace all negative elements from their compounds, with the exceptions of oxygen and fluorine only. 

Iodine trichloride [865-44-1], IQ3, mol wt 233.39, 54.40% I, is a yellow or brownish powder. It is pungent and has a very irritating odor. It decomposes at 77°C into IQ and Q2. It is prepared by adding finely powdered iodine to an excess of liquid chlorine. It is used as a chlorinating and oxidizing agent (120). 

A non-aromatic A5-iodane was obtained by a combination of chlorination and oxidation with NaOCl of ds-io do cycloprop anecarboxylic acid (Scheme 20). Its A3-analog has also been prepared by hydrolysis of the dichloride [58]. 

Furosemide can also be synthesized starting with 2,4-dichlorobenzoic acid (formed by chlorination and oxidation of toluene). Reaction with chlorosulfonic acid is an electrophilic aromatic substitution via the species -S02C1 attacking ortho and para to the chlorines and meta to the carboxy-late. Ammonolysis to the sulfonamide is followed by nucleophilic aromatic substitution of the less hindered chlorine by furfurylamine (obtained from furfural—a product obtained by the hydrolysis of carbohydrates). 

Naphthoquinone pesticides are synthesized either starting from naphthalene via chlorination and oxidation, or starting from naphthoquinone by chlorination. 

Potassium hypochlorite, KOCI, acts like sodium hypochlorite. This reagent is prepared in situ from potassium hydroxide and chlorine and oxidizes primary alcohols to aldehydes [702] and methyl ketones to carboxylic acids [703]. 

Chlorination and oxidation. This reagent is stable and easy to handle. It can be used to introduce chlorine atoms to C-2 of 2-substituted 1,3-dioxolanes, the a-position of aldehydes besides alkenes and alkynes. Oxidation of alcohols such as benzyl alcohol and cyclooctanol in MeCN requires pyridine-DABCO (4 1) as acid scavenger. 

In the presence of base and excess chlorine, both a-chlorination and oxidation may occur. For example, a cyclohexanol-water-calcium carbonate mixmre reacts to form 2-chlorocyclohexanone (Wagner and Zook, 1965a). 

Michael addition of acrylic acid to the chloroamine 32 is straightforward and Friedel-Crafts cyclisation of 35 gives only 31, presumably because the position next to the chlorine atom is slightly disfavoured both sterically and electronically. Chlorination and oxidation are conveniently carried out in the same step and the two halves (26 and 28) of this convergent synthesis are combined to give amopyroquine 25. 

The last part of the de-silverizing proeess is the removal of excess zinc from the lead bullion. This can be achieved in numerous ways, such as chlorination and oxidation, but the accepted practice by major primary smelters is vacuum distillation of the zinc from the bullion. The zinc-rich lead is heated to 600°C, and a vacuum is applied. Zinc distils from the lead and deposits in a solid crystalline state on a... 

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