- Sulphuryl Chloride as an Electrophile. Part 5. Chlorination of Some Anthracene Derivatives; Molecular Orbital Modelling of Substituent Effects
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The rates of electrophilic attack at C-10 of some 9-substituted anthracenes (9-H, Br, CHO, CN, NO2, OMe, or Bz) by sulphuryl chloride have been measured (in PhCl 298 K).The substituent effects roughly parallel those expected from considering the simpler p-XC6H4 system (ρ -1.51; r 0.975); better agreement (ρ -1.23 +/- 0.05; r 0.994) comes by using Dewar's FMMF treatment.MNDO calculations of the energy and optimised geometry of the intermediate ?-complex show a folded structure which allows a degree of sp3 character of the C-10 atom while maintaining sufficient delocalisation of the extended ?-system in the anthracenium ion.The Bell-Eyring-Polyani principle is followed with a linear correlation between the difference in the calculated energy between each reactant and its ?-complex and the experimentally observed change in free energy during attack by Clδ+.
- Bolton, Roger,Hibbert, Brynn D.,Parand, Simin
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- IBX works efficiently under solvent free conditions in ball milling
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IBX (2-iodoxybenzoic acid), discovered in 1893, is an oxidant in synthetic chemistry whose extensive use is impeded by its explosiveness at high temperature and poor solubility in common organic solvents except DMSO. Since the discovery of Dess-Martin Periodinane in 1983, several modified IBX systems have been reported. However, under ball milling conditions, IBX works efficiently with various organic functionalities at ambient temperature under solvent free conditions. Also, the waste IBA (2-iodosobenzoic acid) produced from the reactions was in situ oxidized to IBX in the following step using oxone and thus reused for multiple cycles by conserving its efficiency (only ~6% loss after 15 cycles). This work describes an overview of a highly economical synthetic methodology which overcomes the problems of using IBX, efficiently in gram scale and in a non-explosive way. This journal is the Partner Organisations 2014.
- Achar, Tapas Kumar,Maiti, Saikat,Mal, Prasenjit
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p. 12834 - 12839
(2014/04/03)
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- Microwave-assisted Vilsmeier-Haack formylation of aromatic substrates
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A microwave-assisted Vilsmeier-Haack formylation reaction has been studied on various amines, phenols and polynuclear hydrocarbons under solvent free condition that rapidly affords higher yield of products compared to traditional thermal condition.
- Ghosh, Kumaresh,Adhikari, Suman
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experimental part
p. 959 - 961
(2009/12/24)
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- Process for nucleophilic fluoroalkylation of aldehydes
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Aryl difluoromethyl sulfone adds to alkehydes under phase transfer conditions to give novel substituted alcohols of the general formula wherein R is an aryl, cycloaliphatic, sec- or tert-aliphatic, or heterocyclic group and Ar is an aryl group. The substituted alcohols of formula I are of particular utility as intermediates in the synthesis of a variety of useful end products. For example, the products of formula I may be utilized in desulfonylation reactions, oxidation reactions and fluorination reactions.
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