S N2 character of hydrolysis of benzoyl chloride

Bentley, T. William; Carter, Gillian E.; Harris, H. C.

doi:10.1039/c39840000387

Cited by 20 publications

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“…Solvolysis of BzCl is essentially a solvent mediated reaction in which water acts as a nucleophile, and the rate of the reaction is primarily governed by the stability of the intermediate acylium carbocation, which in turn is dependent on the polarity of the environment. 49 As evidenced from the figure, the rate of reaction slows down with increasing HPC concentration; for 5% HPC the rate is 0.12 s −1 , while for 10% it is 0.07 s −1 ; however, with 20% and higher HPC concentrations, it decreases rapidly to a value of ∼6 × 10 −3 s −1 . Note that due to the very high absorption of cellulose in this region, we could not measure the kinetics for 40% HPC solution.…”

Section: ■ Materials and Methodsmentioning

confidence: 84%

Slow Relaxation Dynamics of Water in Hydroxypropyl Cellulose-Water Mixture Traces Its Phase Transition Pathway: A Spectroscopic Investigation

2012

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In this study, we have explored the slow (of the order of several hundreds of picoseconds) relaxation dynamics of water associated with the hydration shell of a biocompatible polymer, hydroxypropyl cellulose (HPC)-water mixture as a function of HPC concentration using time-resolved fluorescence spectroscopy. The relaxation dynamics slows down with a progressive increase in HPC content indicating restriction of the relaxation pathway of water molecules specially beyond a cellulose concentration of 20% wherein an isotropic to liquid crystalline cholesteric microscopic phase separation sets in. The activation energy calculated from the temperature dependent solvation dynamics studies also shows a similar trend. The nucleophilic activity of water molecules in these mixtures is determined by measuring the reaction kinetics of solvolysis of benzoyl chloride, and the reaction rate exhibits a marked decrease as the phase separation sets in. The observed results are correlated with a transition between the 'bulk' and 'bound' type of water molecules present in the system.

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Section: ■ Materials and Methodsmentioning

confidence: 84%

Slow Relaxation Dynamics of Water in Hydroxypropyl Cellulose-Water Mixture Traces Its Phase Transition Pathway: A Spectroscopic Investigation

2012

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“…In contrast, when the cationic mechanism ( Figure 1 a) operates, there is a much higher and positive slope (e.g., see Figure 1 of Reference [ 66 ]). Consequently, it is possible to detect a change in mechanism from third order to cationic by plotting log k obs vs. Y ; e.g., for solvolyses of benzoyl chloride ( 1 , Z = H) in a wide range of acetone-water mixtures [ 67 ]. In addition, a much clearer change in slopes is obtained by plotting log k 3 vs. Y (Equation (3)) instead of log k obs ; the two plots are compared in Figure 6 .…”

Section: Resultsmentioning

confidence: 99%

Calculated Third Order Rate Constants for Interpreting the Mechanisms of Hydrolyses of Chloroformates, Carboxylic Acid Halides, Sulfonyl Chlorides and Phosphorochloridates

2015

IJMS

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Hydrolyses of acid derivatives (e.g., carboxylic acid chlorides and fluorides, fluoro- and chloroformates, sulfonyl chlorides, phosphorochloridates, anhydrides) exhibit pseudo-first order kinetics. Reaction mechanisms vary from those involving a cationic intermediate (SN1) to concerted SN2 processes, and further to third order reactions, in which one solvent molecule acts as the attacking nucleophile and a second molecule acts as a general base catalyst. A unified framework is discussed, in which there are two reaction channels—an SN1-SN2 spectrum and an SN2-SN3 spectrum. Third order rate constants (k3) are calculated for solvolytic reactions in a wide range of compositions of acetone-water mixtures, and are shown to be either approximately constant or correlated with the Grunwald-Winstein Y parameter. These data and kinetic solvent isotope effects, provide the experimental evidence for the SN2-SN3 spectrum (e.g., for chloro- and fluoroformates, chloroacetyl chloride, p-nitrobenzoyl p-toluenesulfonate, sulfonyl chlorides). Deviations from linearity lead to U- or V-shaped plots, which assist in the identification of the point at which the reaction channel changes from SN2-SN3 to SN1-SN2 (e.g., for benzoyl chloride).

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“…Our selection of this model system is based on several factors34: Benzoyl halides are virtually water‐insoluble but are highly CO 2 ‐soluble. Hydrolysis of benzoyl halides is irreversible, greatly facilitating interpretation of kinetic data. In an aqueous solvent, water is present in excess and the hydrolysis reaction can be treated as first order with respect to the halide. The second‐order hydrolysis reaction rate constant for benzoyl chloride is much smaller in nonpolar solvents, such as tetrahydrofuran,42 than in water 43–48 …”

Section: Methodsmentioning

confidence: 99%

“…The second‐order hydrolysis reaction rate constant for benzoyl chloride is much smaller in nonpolar solvents, such as tetrahydrofuran,42 than in water 43–48…”

Section: Methodsmentioning

confidence: 99%

Reaction rates in ultrasonic emulsions of dense carbon dioxide and water

Timko¹,

Smith²,

Danheiser³

et al. 2005

AIChE Journal

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S N2 character of hydrolysis of benzoyl chloride

Abstract: Solvent effects on reactivity for hydrolysis/alcoholysis of benzoyl chloride are consistent with a direct displacement reaction having SN2 character, in competition with a carbonyl addition reaction becoming dominant in less aqueous media.

Cited by 20 publications

References 0 publications

Slow Relaxation Dynamics of Water in Hydroxypropyl Cellulose-Water Mixture Traces Its Phase Transition Pathway: A Spectroscopic Investigation

Slow Relaxation Dynamics of Water in Hydroxypropyl Cellulose-Water Mixture Traces Its Phase Transition Pathway: A Spectroscopic Investigation

Calculated Third Order Rate Constants for Interpreting the Mechanisms of Hydrolyses of Chloroformates, Carboxylic Acid Halides, Sulfonyl Chlorides and Phosphorochloridates

Reaction rates in ultrasonic emulsions of dense carbon dioxide and water

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