造纸专业英语1

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1、ReactioninAlkalineCookingDuringkraftpulpingligninfragmentationisperformedbythecleavageofaryletherbondsandformationofnewphenolicgroups,whichincreasethehydrophilicityandsolubilityoflignin.Thereactionsoflignininakraftcookarecomplexandstillnotcompletelyunderstood,butthem

2、ainreactionsleadingtothelignindegradationinalkalineconditionshavebeenwellreviewed.Themostimportantdelignifyingreactioninalkalineconditionsisthecleavageofβ-aryletherlinkages,whicharethemostprominentligninstructures.ReactioninAlkalineCookingInkraftpulpingconditionsther

3、eactionofhydrosulphideionswithquinonemethidesleadstothecleavageofβ-O-4-linkages,whereasintheabsenceofhydrosulphideions,suchasinthesodacook,thedominatingreactionistheeliminationofγ-hydroxymethylorβ-proton,whichleadstotheformationofformaldehydeandenoletherstructures.In

4、additiontohydrosulphideions,anthraquinone(AQ)andpolysulphide(PS)havealsobeenfoundtoenhancethecleavageofβ-aryletherlinkages.hydrosulphide硫氢化物methide甲基化合物hydroxymethyl羟甲基formaldehyde甲醛aldehyde醛，乙醛form-甲酸，甲酰enol【化】烯醇anthraquinone蒽醌anthrahydroquinone蒽氢醌polysulphide多硫化物po

5、ly-表示“聚、聚合”之义ReactioninAlkalineCookingThecleavageofnon-phenolicβ-aryletherbondsisthedominatingandratedeterminingreactioninalkalinelignindegradation.Theetherifiedβ-aryletherlinkagesarecleavedbyhydroxideionsviaanoxiraneintermediate.Thisreactionisnotaffectedbysodiumsulp

6、hideoranthraquinone,butforexampleα-carbonylshavebeenshowntoacceleratethecleavageofβ-aryletherlinkagesinnon-phenolicligninunits.oxirane-ane-ene-yne环氧epoxide环氧化物carbonyl【化】羰基carboxyl羧基carboxylic羧酸的ReactioninAlkalineCookingBecausethereactionisintramolecular,thestereostr

7、ucturealsoaffectsthereactivityandtheerythroformoftheβ-O-4structurehasbeenfoundtobemorereactivethanthecorrespondingthreoform.erythroform赤式threoform苏式ReactioninAlkalineCookingThephenolicα-aryletherbondsarecleavedmosteasily,butsincetheamountofnon-cyclicα-aryletherstruct

8、uresislowcomparedtotheβ-O-4structurestheircleavagedoesnotleadtothemajordegradationoflignin.Thecleavageoftheα-etherbondsofphenolicph