Electrostatic Switching between S                         N                         1 and S                         N                         2 Pathways

Li Juan Yu; Michelle L. Coote

doi:10.1021/acs.jpca.8b11579

Electrostatic Switching between S _N 1 and S _N 2 Pathways

Li Juan Yu
, Michelle L. Coote^*

^*Corresponding author for this work

Research output: Contribution to journal › Article › peer-review

42 Citations (Scopus)

Abstract

A test set 264 nucleophilic substitution reactions was studied via accurate quantum chemical reactions to establish the relative preferences for S _N 1 versus S _N 2 mechanisms. In low polar solvents, reactions involving anionic nucleophiles and leaving groups favored S _N 2 pathways. In contrast, S _N 1 is preferred for those reactions involving neutral nucleophiles and leaving groups except where the carbocation intermediates are exceptionally unstable. For neutral nucleophiles and anionic leaving groups, S _N 2 is generally preferred over S _N 1 except for exceptionally stable carbocation intermediates. On the basis of these studies, candidate reactions for which distinct S _N 1 or S _N 2 preferences could be reversed by electric fields were selected. As proof of concept, the S _N 1/S _N 2 preferences for the reaction of tBu-triflate with pyridine (S _N 2 to S _N 1) and with piperidine (S _N 1 to S _N 2) were switched by both charged functional groups and point charges (i.e., electric fields) along the reaction axis, with a positive charge on the nucleophile side favoring S _N 1 and a negative charge favoring S _N 2 for these reactions.

Original language	English
Pages (from-to)	582-589
Number of pages	8
Journal	Journal of Physical Chemistry A
Volume	123
Issue number	2
DOIs	https://doi.org/10.1021/acs.jpca.8b11579
Publication status	Published - 17 Jan 2019

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@article{a9152f5a5f1344bc96e74ef55578e8d8,

title = " Electrostatic Switching between S N 1 and S N 2 Pathways ",

abstract = " A test set 264 nucleophilic substitution reactions was studied via accurate quantum chemical reactions to establish the relative preferences for S N 1 versus S N 2 mechanisms. In low polar solvents, reactions involving anionic nucleophiles and leaving groups favored S N 2 pathways. In contrast, S N 1 is preferred for those reactions involving neutral nucleophiles and leaving groups except where the carbocation intermediates are exceptionally unstable. For neutral nucleophiles and anionic leaving groups, S N 2 is generally preferred over S N 1 except for exceptionally stable carbocation intermediates. On the basis of these studies, candidate reactions for which distinct S N 1 or S N 2 preferences could be reversed by electric fields were selected. As proof of concept, the S N 1/S N 2 preferences for the reaction of tBu-triflate with pyridine (S N 2 to S N 1) and with piperidine (S N 1 to S N 2) were switched by both charged functional groups and point charges (i.e., electric fields) along the reaction axis, with a positive charge on the nucleophile side favoring S N 1 and a negative charge favoring S N 2 for these reactions.",

author = "Yu, \{Li Juan\} and Coote, \{Michelle L.\}",

note = "Publisher Copyright: {\textcopyright} 2018 American Chemical Society.",

year = "2019",

month = jan,

day = "17",

doi = "10.1021/acs.jpca.8b11579",

language = "English",

volume = "123",

pages = "582--589",

journal = "Journal of Physical Chemistry A",

issn = "1089-5639",

publisher = "American Chemical Society",

number = "2",

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Electrostatic Switching between S _N 1 and S _N 2 Pathways . / Yu, Li Juan; Coote, Michelle L.
In: Journal of Physical Chemistry A, Vol. 123, No. 2, 17.01.2019, p. 582-589.

Research output: Contribution to journal › Article › peer-review

TY - JOUR

T1 - Electrostatic Switching between S N 1 and S N 2 Pathways

AU - Yu, Li Juan

AU - Coote, Michelle L.

PY - 2019/1/17

Y1 - 2019/1/17

N2 - A test set 264 nucleophilic substitution reactions was studied via accurate quantum chemical reactions to establish the relative preferences for S N 1 versus S N 2 mechanisms. In low polar solvents, reactions involving anionic nucleophiles and leaving groups favored S N 2 pathways. In contrast, S N 1 is preferred for those reactions involving neutral nucleophiles and leaving groups except where the carbocation intermediates are exceptionally unstable. For neutral nucleophiles and anionic leaving groups, S N 2 is generally preferred over S N 1 except for exceptionally stable carbocation intermediates. On the basis of these studies, candidate reactions for which distinct S N 1 or S N 2 preferences could be reversed by electric fields were selected. As proof of concept, the S N 1/S N 2 preferences for the reaction of tBu-triflate with pyridine (S N 2 to S N 1) and with piperidine (S N 1 to S N 2) were switched by both charged functional groups and point charges (i.e., electric fields) along the reaction axis, with a positive charge on the nucleophile side favoring S N 1 and a negative charge favoring S N 2 for these reactions.

AB - A test set 264 nucleophilic substitution reactions was studied via accurate quantum chemical reactions to establish the relative preferences for S N 1 versus S N 2 mechanisms. In low polar solvents, reactions involving anionic nucleophiles and leaving groups favored S N 2 pathways. In contrast, S N 1 is preferred for those reactions involving neutral nucleophiles and leaving groups except where the carbocation intermediates are exceptionally unstable. For neutral nucleophiles and anionic leaving groups, S N 2 is generally preferred over S N 1 except for exceptionally stable carbocation intermediates. On the basis of these studies, candidate reactions for which distinct S N 1 or S N 2 preferences could be reversed by electric fields were selected. As proof of concept, the S N 1/S N 2 preferences for the reaction of tBu-triflate with pyridine (S N 2 to S N 1) and with piperidine (S N 1 to S N 2) were switched by both charged functional groups and point charges (i.e., electric fields) along the reaction axis, with a positive charge on the nucleophile side favoring S N 1 and a negative charge favoring S N 2 for these reactions.

UR - https://www.scopus.com/pages/publications/85059621616

U2 - 10.1021/acs.jpca.8b11579

DO - 10.1021/acs.jpca.8b11579

M3 - Article

SN - 1089-5639

VL - 123

SP - 582

EP - 589

JO - Journal of Physical Chemistry A

JF - Journal of Physical Chemistry A

IS - 2

ER -

Electrostatic Switching between S _N 1 and S _N 2 Pathways

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