11. Interfacial Mechanism and Kinetics of Phase-Transfer Catalysis
11. Interfacial Mechanism and Kinetics of Phase-Transfer Catalysis
11. Interfacial Mechanism and Kinetics of Phase-Transfer Catalysis
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SYMBOLSaactivity <strong>of</strong> quaternary salt in a solutionA interfacial area between the organic <strong>and</strong> aqueous phase ðm 2 )A s surface area <strong>of</strong> solid particles ðdm 2 )Aliquat 336 tricaprylmethylammonium chlorideCconcentration <strong>of</strong> quaternary saltC j iconcentration <strong>of</strong> component i in phase j (j ¼ org:, aq., cat.)C PhOQ dimensionless concentration <strong>of</strong> PhOQC# number <strong>of</strong> carbon atoms in each <strong>of</strong> the four alkyl chains in the quaternarycationD Q distribution coefficient <strong>of</strong> quaternary cation definedEQX T true extraction constant ðkmol=m 3 Þ 1jhydration number per quaternary salt in the organic phasek app apparent first-order reaction-rate constant (s 1 )k app;0 initial apparent reaction rate constant (1/min)k 2 forward reaction rate constant <strong>of</strong> the aqueous phase (kmol=m 3 minÞ 1k 2 reverse reaction rate constant <strong>of</strong> the aqueous phase ðkmol=m 3 minÞ 1k ireaction rate constantK iequilibrium constantK da dissociation constant <strong>of</strong> QX in the aqueous phase (kmol=m 3 )K do dissociation constant <strong>of</strong> QX in the organic phase (kmol=m 3 )K QY mass transfer coefficient <strong>of</strong> QY (m/min)K QX overall mass transfer coefficient <strong>of</strong> QX (kmol=m 3 min 1 )mdistribution coefficient <strong>of</strong> onium saltM H molecular weight <strong>of</strong> hydrophilic group in quaternary salt (e.g., N þ X )M T molecular weight <strong>of</strong> quaternary saltM TBAB molecular weight <strong>of</strong> TBABMX side product in the aqueous solutionMY aqueous reactantQ þ quaternary cationQX quaternary saltrspatial co-ordinate in radial directionr cmean radius <strong>of</strong> droplet containing organic phase <strong>and</strong> catalyst phase (m)r dmean radius <strong>of</strong> organic droplet (m)R freaction rate per unit area (mol=m 2 sÞRH reactantRX organic reactantR 0 X organic reactantttimeTabsolute temperature (K)TBAB tetra-n-butylammonium bromideTBAC tetra-n-butylammonium chlorideTBAI tetra-n-butylammonium iodideTBA-TBPO tetra-n-butylammonium 2,4,6-tribromophenoxideTBPB tetra-n-butylphosphonium bromideV volume <strong>of</strong> aqueous phase (m 3 )V aq volume <strong>of</strong> aqueous phase (L)volume <strong>of</strong> catalyst phase (L)V catCopyright © 2003 by Taylor & Francis Group, LLC
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