Influence of Sulfur for Oxygen Substitution in the Solvolytic Reactions of Chloroformate Esters and Related Compounds

D’Souza, Malcolm J.; Kevill, Dennis N.

doi:10.3390/ijms151018310

Cited by 9 publications

(12 citation statements)

References 80 publications

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“…The Wesley chemistry undergraduate research projects have a two-fold focus: (1) small-molecule synthesis for use in chemometric methods for solution chemical kinetics (D’Souza and Kevill, 2014; D’Souza and Kevill, 2013; Kevill and D’Souza, 2008), and (2) cheminformatics (D’Souza and Barile et al, 2015; D’Souza et al 2013; D’Souza et al, 2011; D’Souza and AlAbed, 2010; D’Souza and Gerges, 2010; D’Souza et al 2009; D’Souza and Kyoshi, 2009; D’Souza et al, 2009; D’Souza, 2008; D’Souza, 2007; D’Souza, 2005). …”

Section: The Directed Research Program In Chemistrymentioning

confidence: 99%

“…Such experiments have led to better methods for measuring and understanding the effects of the solvent (medium) in which these reactions take place (D’Souza and Kevill, 2014; D’Souza and Kevill, 2013; Kevill and D’Souza, 2008). Undergraduates trained in such techniques have then completed more sophisticated advanced molecular reaction dynamics and chemical kinetics summer internship projects in the Department of Chemistry & Biochemistry at UD.…”

Section: The Directed Research Program In Chemistrymentioning

confidence: 99%

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Integrative Biological Chemistry Program Includes The Use Of Informatics Tools, GIS And SAS Software Applications

D’Souza¹,

Kashmar²,

Hurst³

et al. 2015

CIER

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Wesley College is a private, primarily undergraduate minority-serving institution located in the historic district of Dover, Delaware (DE). The College recently revised its baccalaureate biological chemistry program requirements to include a one-semester Physical Chemistry for the Life Sciences course and project-based experiential learning courses using instrumentation, datacollection, data-storage, statistical-modeling analysis, visualization, and computational techniques. In this revised curriculum, students begin with a traditional set of biology, chemistry, physics, and mathematics major core-requirements, a geographic information systems (GIS) course, a choice of an instrumental analysis course or a statistical analysis systems (SAS) programming course, and then, students can add major-electives that further add depth and value to their future postgraduate specialty areas. Open-sourced georeferenced census, health and health disparity data were coupled with GIS and SAS tools, in a public health surveillance system project, based on US county zip-codes, to develop use-cases for chronic adult obesity where income, poverty status, health insurance coverage, education, and age were categorical variables. Across the 48 contiguous states, obesity rates are found to be directly proportional to high poverty and inversely proportional to median income and educational achievement. For the State of Delaware, age and educational attainment were found to be limiting obesity risk-factors in its adult population. Furthermore, the 2004-2010 obesity trends showed that for two of the less densely populated Delaware counties; Sussex and Kent, the rates of adult obesity were found to be progressing at much higher proportions when compared to the national average.

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Section: The Directed Research Program In Chemistrymentioning

confidence: 99%

Section: The Directed Research Program In Chemistrymentioning

confidence: 99%

Integrative Biological Chemistry Program Includes The Use Of Informatics Tools, GIS And SAS Software Applications

D’Souza¹,

Kashmar²,

Hurst³

et al. 2015

CIER

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“…The solvent mix includes the highly ionizing mixtures of aqueous fluoroalcohols where a unimolecular S N 1-type (ionization) mechanism was proposed for several chloroformates [31, 33, 34]. …”

Section: Resultsmentioning

confidence: 99%

Statistical Methods for the Investigation of Solvolysis Mechanisms Illustrated by the Chlorides of the Carbomethoxy Protecting Groups NVOC and FMOC

D’Souza

Deol

Pavey

et al. 2015

Journal of Analytical Methods in Chemistry

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The solvolysis of 4,5-dimethoxy-2-nitrobenzyl chloroformate (NVOC-Cl, 1) is followed at 25.0°C in twenty hydroxylic solvents. A comparison with previously published rates for benzyl chloroformate and p-nitrobenzyl chloroformate indicates that the inductive effect of the nitro and the two methoxy groups strongly influences the rate of reaction. For 1, the specific rates of solvolysis are correlated using an extended Grunwald-Winstein (G-W) treatment. A direct comparison with the data for phenyl chloroformate (PhOCOCl) in identical solvents strongly suggests that the addition step within an addition-elimination mechanism is rate-determining for both substrates. A reevaluation of the kinetic data for 9-fluorenylmethyl chloroformate (FMOC-Cl, 2) involves a correlation of log⁡(k/k o)2 versus log⁡(k/k o)PhOCOCl. In this plot, deviations were observed in solvents rich in a hydrogen-bonding fluoroalcohol component. Omitting the aqueous fluoroalcohol rate measurements for 2 in an analysis using the extended G-W equation suggested the occurrence of dual pathways differing in the dependences upon the ionizing power and nucleophilicity of the solvent. In addition, the fluorenyl ring is rotated out of the plane containing the ether oxygen and, as a result, PhOCOCl is found to solvolyze 20 times faster than 2 in ethanol and methanol.

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“…2.96 and for phenyl chlorodithioformate of ca . 0.72 [17] are often taken as typical values for addition-elimination reaction, with addition rate-determining, and for ionization with moderate assistance from nucleophilic solvation, respectively; d Multiple correlation coefficient; e Calculated using the original Y scale, which is based on the first-order rate coefficients for solvolyses of tert -butyl chloride; f With omission of the four 2,2,2-trifluoroethanol (TFE)-ethanol mixed solvents; g Morpholine with an N -chloroformyl substituent; h The 1-adamantyl group.…”

Section: Solvolyses Of Nn-dialkylcarbamoyl Chloridesmentioning

confidence: 99%

“…Studies of the solvolysis reactions of the closely related haloformate esters [16] and of the effects of sulfur for oxygen substitution upon those solvolyses [17] have recently been reviewed. The influence of temperature can lead to energies and entropies of activation, with entropies of activation being useful in distinguishing between unimolecular and bimolecular pathways, with the latter tending to have appreciably negative values due to two species being associated, with a restricted orientation, at the transition state [18].…”

Section: Introductionmentioning

confidence: 99%

Mechanistic Studies of the Solvolyses of Carbamoyl Chlorides and Related Reactions

D’Souza

Kevill

2016

IJMS

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Carbamoyl chlorides are important intermediates, both in the research laboratory and in industrial scale syntheses. The most studied and used are the disubstituted derivatives, incorporating either aryl or alkyl groups (Ar2NCOCl or R2NCOCl). Sometimes, the groups are tied back to give a ring and piperidino- and morpholino-derivatives are commonly encountered. Some studies have been made with two different groups attached. Solvolyses tend to occur at the carbonyl carbon, with replacement of the chloride ion. Studies of both rate and products are reviewed and the solvolysis reactions are usually SN1, although addition of an amine leads to a superimposable bimolecular component. Many of the studies under solvolytic conditions include the application of the extended Grunwald–Winstein equation. The monosubstituted derivatives (ArNHCOCl or RNHCOCl) are less studied. They are readily prepared by the addition of HCl to an isocyanate. In acetonitrile, they decompose to set up and reach equilibrium with the isocyanate (ArNCO or RNCO) and HCl. Considering that the structurally related formyl chloride (HOCOCl) is highly unstable (with formation of HCl + CO2), the unsubstituted carbamoyl chloride (H2NCOCl) is remarkably stable. Recommended synthetic procedures require it to survive reaction temperatures in the 300–400 °C range. There has been very little study of its reactions.

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Influence of Sulfur for Oxygen Substitution in the Solvolytic Reactions of Chloroformate Esters and Related Compounds

Cited by 9 publications

References 80 publications

Integrative Biological Chemistry Program Includes The Use Of Informatics Tools, GIS And SAS Software Applications

Integrative Biological Chemistry Program Includes The Use Of Informatics Tools, GIS And SAS Software Applications

Statistical Methods for the Investigation of Solvolysis Mechanisms Illustrated by the Chlorides of the Carbomethoxy Protecting Groups NVOC and FMOC

Mechanistic Studies of the Solvolyses of Carbamoyl Chlorides and Related Reactions

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