The uranyl unit as electrophilic catalyst of acyl transfer reactions

Valeria van Axel Castelli; V. van Axel castelli; Roberta Cacciapaglia; Gabriela Chiosis; F.C.J.M. van Veggel; Luigi Mandolini; David Reinhoudt

doi:10.1016/0020-1693(96)05065-7

The uranyl unit as electrophilic catalyst of acyl transfer reactions

Valeria van Axel Castelli, V. van Axel castelli, Roberta Cacciapaglia, Gabriela Chiosis, F.C.J.M. van Veggel, Luigi Mandolini, David Reinhoudt

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Abstract

The kinetics of the base induced alcoholysis of a series of metallomacrocycles in which the salophen-uranyl unit is connected by polymethylene bridges of variable length to a pyrogallol monoacetate unit have been investigated in the MeO−Me4N+/MeOH and EtO−Me4N+/EtOH base-solvent systems. Analysis of rate data collected over a wide range of base concentrations, coupled with equilibrium measurements for complex formation between the alkoxide ion and the uranyl centre, showed that the ester cleavage processes are the results of two competing pathways involving alkoxide ion attack on uncomplexed and alkoxide-complexed substrates. Rate data related to the former pathway show that the proximal uranyl centre activates the ester carbonyl towards nucleophilic addition, thus behaving as an immobilized Lewis acid catalyst. The size of the acceleration critically depends on both solvent nature and distance of the ester function from the metal electrophile.

Original language	Undefined
Pages (from-to)	181-193
Journal	Inorganica chimica acta
Volume	246
Issue number	246
DOIs	https://doi.org/10.1016/0020-1693(96)05065-7
Publication status	Published - 1996

Keywords

METIS-105914
IR-10940

Access to Document

10.1016/0020-1693(96)05065-7

K10940__

Cite this

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title = "The uranyl unit as electrophilic catalyst of acyl transfer reactions",

abstract = "The kinetics of the base induced alcoholysis of a series of metallomacrocycles in which the salophen-uranyl unit is connected by polymethylene bridges of variable length to a pyrogallol monoacetate unit have been investigated in the MeO−Me4N+/MeOH and EtO−Me4N+/EtOH base-solvent systems. Analysis of rate data collected over a wide range of base concentrations, coupled with equilibrium measurements for complex formation between the alkoxide ion and the uranyl centre, showed that the ester cleavage processes are the results of two competing pathways involving alkoxide ion attack on uncomplexed and alkoxide-complexed substrates. Rate data related to the former pathway show that the proximal uranyl centre activates the ester carbonyl towards nucleophilic addition, thus behaving as an immobilized Lewis acid catalyst. The size of the acceleration critically depends on both solvent nature and distance of the ester function from the metal electrophile.",

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author = "{van Axel Castelli}, Valeria and {van Axel castelli}, V. and Roberta Cacciapaglia and Gabriela Chiosis and {van Veggel}, F.C.J.M. and Luigi Mandolini and David Reinhoudt",

year = "1996",

doi = "10.1016/0020-1693(96)05065-7",

language = "Undefined",

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issn = "0020-1693",

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TY - JOUR

T1 - The uranyl unit as electrophilic catalyst of acyl transfer reactions

AU - van Axel Castelli, Valeria

AU - van Axel castelli, V.

AU - Cacciapaglia, Roberta

AU - Chiosis, Gabriela

AU - van Veggel, F.C.J.M.

AU - Mandolini, Luigi

AU - Reinhoudt, David

PY - 1996

Y1 - 1996

N2 - The kinetics of the base induced alcoholysis of a series of metallomacrocycles in which the salophen-uranyl unit is connected by polymethylene bridges of variable length to a pyrogallol monoacetate unit have been investigated in the MeO−Me4N+/MeOH and EtO−Me4N+/EtOH base-solvent systems. Analysis of rate data collected over a wide range of base concentrations, coupled with equilibrium measurements for complex formation between the alkoxide ion and the uranyl centre, showed that the ester cleavage processes are the results of two competing pathways involving alkoxide ion attack on uncomplexed and alkoxide-complexed substrates. Rate data related to the former pathway show that the proximal uranyl centre activates the ester carbonyl towards nucleophilic addition, thus behaving as an immobilized Lewis acid catalyst. The size of the acceleration critically depends on both solvent nature and distance of the ester function from the metal electrophile.

AB - The kinetics of the base induced alcoholysis of a series of metallomacrocycles in which the salophen-uranyl unit is connected by polymethylene bridges of variable length to a pyrogallol monoacetate unit have been investigated in the MeO−Me4N+/MeOH and EtO−Me4N+/EtOH base-solvent systems. Analysis of rate data collected over a wide range of base concentrations, coupled with equilibrium measurements for complex formation between the alkoxide ion and the uranyl centre, showed that the ester cleavage processes are the results of two competing pathways involving alkoxide ion attack on uncomplexed and alkoxide-complexed substrates. Rate data related to the former pathway show that the proximal uranyl centre activates the ester carbonyl towards nucleophilic addition, thus behaving as an immobilized Lewis acid catalyst. The size of the acceleration critically depends on both solvent nature and distance of the ester function from the metal electrophile.

KW - METIS-105914

KW - IR-10940

U2 - 10.1016/0020-1693(96)05065-7

DO - 10.1016/0020-1693(96)05065-7

M3 - Article

SN - 0020-1693

VL - 246

SP - 181

EP - 193

JO - Inorganica chimica acta

JF - Inorganica chimica acta

IS - 246

ER -