- Regioselective synthesis of important chlorophenols in the presence of methylthioalkanes with remote SMe, OMe or OH substituents
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Various methylthio alcohols, methoxy(methylthio)alkanes and bis(methylthio)alkanes have been used as regioselectivity modifiers in the chlorination reactions of various phenols at room temperature. The process involves the use of a slight excess of sulfuryl chloride in the presence of aluminum or ferric chloride as an activator. Methylthio alcohols, methoxy(methylthio)alkanes and bis(methylthio)alkanes having 2 and 3 methylene groups as a spacer were found to be good for the para-selective chlorination of o-cresol and phenol. On the other hand, methylthio alcohols, methoxy(methylthio)alkanes and bis(methylthio)alkanes having 6 and 9 methylene groups were found to be good for the selective para-chlorination of m-xylenol and m-cresol. Calculations using density functional theory on bis(methylthio)alkanes have suggested two different types of stable chlorinated intermediates depending on the number of methylene units as a spacer.
- Smith, Keith,Al-Zuhairi, Ali J.,Elliott, Mark. C.,El-Hiti, Gamal A.
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p. 607 - 621
(2018/07/13)
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- Selective water-based oxychlorination of phenol with hydrogen peroxide catalyzed by manganous sulfate
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An efficient method for the selective oxychlorination of phenol to 2,4-dichlorophenol catalyzed by manganous(ii) sulfate is developed using hydrogen chloride as a chlorinating source, hydrogen peroxide as an oxidant and water as a solvent. The catalyst has high activity and selectivity under mild conditions. The products are automatically isolated from aqueous solution, which also contains the catalyst at the end of the reaction, and hence product separation and catalyst recycling are both simple in this system. The performance of manganous(ii) sulfate with the oxidative chlorinating system HCl/H2O2 indicates that this is a promising synthetic method for the manufacture of various 2,4-dichlorophenol derivatives.
- Xin, Hongchuan,Yang, Shilei,An, Baigang,An, Zengjian
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p. 13467 - 13472
(2017/03/11)
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- Highly Selective Aromatic Chlorinations. Part 2. The Chlorination of Substituted Phenols, Anisoles, Anilines, and Related Compounds with N-Chloroamines in Acidic Solution
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Phenols, anisoles, anilines, and related compounds are chlorinated in trifluoroacetic acid at room temperature by N-chlorodialkylamines and N-chlorotrialkylammonium salts.With monsubstituted compounds and their 2- and 3-substituted derivatives the reaction occurs efficiently and selectively at the 4-position.The reactivity of these substrates and the selectivity of their chlorinations are determined by electronic rather than steric effects of the substituent.Blocking the reaction with a substituent at the 4-position generally leads to only poor or moderate yields of the 2-chlorinated product.Evidence for radical and cation radical intermediates has been obtained in the reactions of some of the 4-substituted reactants and the mechanism of chlorination is discussed in the light of these findings.The reactions of selected substrates have been scaled up to give laboratory syntheses.
- Smith, John R. Lindsay,McKeer, Linda C.,Taylor, Jonathan M.
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p. 385 - 392
(2007/10/02)
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- Method of disinfecting premises from coccidial oocysts using generated ammonia
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A method of disinfecting premises from coccidial oocysts in which surface to be disinfected is thoroughly wetted with a first aqueous solution of ammonium salt containing approximately 0.5 to 1.5 molar of ammonium together with non-ionic surfactant and indicator having a color change in the region of pH 8 to pH 10 and the wetted surface is then covered with sufficient of a second aqueous solution of alkali metal hydroxide containing approximately 0.75 to 2.3 molar of hydroxide toether with phenolic bactericide to cause the indicator to change color on the treated surface. A preparation for use in such a method comprises a first package containing ammonium salt together with non-ionic surfactant and indicator and second package containing alkali metal hydroxide and phenolic bactericide, the molar amount of hydroxide in the second package being greater than the molar amount of ammonium in the first package.
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