title: Mechanistic aspects of the nucleophilic substitution of pectin. On the formation of chloromethane.
abstract: Chloromethane, accounting for approximately 16% of the tropospheric chlorine, is mainly coming from natural sources. However anthropogenic activities, such as combustion of biomass may contribute significantly as well. The present study focuses on the thermal solid state reaction between pectin, an important constituent of biomass, and chloride ions as found in alkali metal chlorides. The formation of chloromethane is evident with the amount formed being linear with respect to chloride if pectin is in great excess. Thus the reaction is explained as a pseudo first order SN2 reaction between the chloride ion and the methyl ester moiety in pectin. It is suggested that the polymeric nature of pectin plays an active role by an enhanced transport of halides along the carbohydrate chain. Optimal reaction temperature is around 210°C. At higher temperatures the yield of chloromethane decreases due to a thermal decomposition of the pectin. The possible influence of the type of cation is discussed.
authors.affiliation: Center of Physical Chemical Methods of Research and Analysis, al-Farabi Kazakh National University, 96a Tole bi st, 050012 Almaty, Kazakhstan.
authors.forename: Yerbolat
authors.initials: Y
authors.lastname: Sailaukhanuly
authors.affiliation: Department of Chemical and Biochemical Engineering, Technical University of Denmark, DK-2800 Kgs. Lyngby, Denmark.
authors.forename: Zsuzsa
authors.initials: Z
authors.lastname: Sárossy
authors.affiliation: Awareness Center, Linkøpingvej 35, Trekroner, DK-4000 Roskilde, Denmark.
authors.forename: Lars
authors.initials: L
authors.lastname: Carlsen
authors.affiliation: Department of Chemical and Biochemical Engineering, Technical University of Denmark, DK-2800 Kgs. Lyngby, Denmark. Electronic address: heeg@kt.dtu.dk.
authors.forename: Helge
authors.initials: H
authors.lastname: Egsgaard
mesh_terms: D018533:Biomass; D002712:Chlorides / Q000737:chemistry*; D002713:Chlorine / Q000737:chemistry; D007477:Ions / Q000737:chemistry; D008737:Methyl Chloride / Q000737:chemistry*; D010368:Pectins / Q000737:chemistry*; D013696:Temperature
chemical_list: D002712:Chlorides; D007477:Ions; D002713:Chlorine; D010368:Pectins; D008737:Methyl Chloride
keywords: Alkali metal chlorides; Biomass; Chloromethane; GC–MS; Pectin