Sandmeyer reactions. Part 6. A mechanistic investigation into the reduction and ligand transfer steps of Sandmeyer cyanation

P  Hanson; S C  Rowell; A B  Taylor; P H  Walton; A W  Timms

doi:10.1039/b200747a

Sandmeyer reactions. Part 6. A mechanistic investigation into the reduction and ligand transfer steps of Sandmeyer cyanation

P Hanson, S C Rowell, A B Taylor, P H Walton, A W Timms

Chemistry

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

Abstract

For Sandmeyer cyanation at 298 K in 50% v/v aqueous acetonitrile buffered at pH 8, absolute rate constants have been obtained for the reduction of 4-methoxybenzenediazonium tetrafluoroborate by the cyanocuprate(I) anions Cu-I(CN)(4)(3-), Cu-I(NCMe)(CN)(3)(2-) and Cu-I(NCMe)(2)(CN)(2)(-) as (0.50 +/- 0.05), (0.12 +/- 0.03) and 0.0 dm(3) mol(-1) s(-1), respectively. The relative reactivity of the two reactive cyanocuprates reflects the estimated difference in their standard reduction potentials. Ligand transfer to the aryl radical from the cyanocuprate(II) anions produced in the reaction occurs within the solvent cage. By use of radical clocks, first order rate constants of the order of 1 x 10(8) s(-)1 for ligand transfer between the caged reactants can be evaluated although the transfer rate may vary from one aryl radical to another. No difference was discerned in ligand transferring reactivity between the two cyanocuprate(II) complexes involved.

Original language	English
Pages (from-to)	1126-1134
Number of pages	9
Journal	JOURNAL OF THE CHEMICAL SOCIETY-PERKIN TRANSACTIONS 2
Issue number	6
DOIs	https://doi.org/10.1039/b200747a
Publication status	Published - 2002

Keywords

ABSOLUTE RATE CONSTANTS
PSCHORR RADICAL CLOCK
STABILITY-CONSTANTS
ARYL RADICALS
WATER LIGANDS
BENZENEDIAZONIUM IONS
ARENEDIAZONIUM SALTS
CU-II
COMPLEXES
CHLORIDE

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10.1039/b200747a

Cite this

@article{57db5b2f47384dabab262c134fcebde3,

title = "Sandmeyer reactions. Part 6. A mechanistic investigation into the reduction and ligand transfer steps of Sandmeyer cyanation",

abstract = "For Sandmeyer cyanation at 298 K in 50% v/v aqueous acetonitrile buffered at pH 8, absolute rate constants have been obtained for the reduction of 4-methoxybenzenediazonium tetrafluoroborate by the cyanocuprate(I) anions Cu-I(CN)(4)(3-), Cu-I(NCMe)(CN)(3)(2-) and Cu-I(NCMe)(2)(CN)(2)(-) as (0.50 +/- 0.05), (0.12 +/- 0.03) and 0.0 dm(3) mol(-1) s(-1), respectively. The relative reactivity of the two reactive cyanocuprates reflects the estimated difference in their standard reduction potentials. Ligand transfer to the aryl radical from the cyanocuprate(II) anions produced in the reaction occurs within the solvent cage. By use of radical clocks, first order rate constants of the order of 1 x 10(8) s(-)1 for ligand transfer between the caged reactants can be evaluated although the transfer rate may vary from one aryl radical to another. No difference was discerned in ligand transferring reactivity between the two cyanocuprate(II) complexes involved.",

keywords = "ABSOLUTE RATE CONSTANTS, PSCHORR RADICAL CLOCK, STABILITY-CONSTANTS, ARYL RADICALS, WATER LIGANDS, BENZENEDIAZONIUM IONS, ARENEDIAZONIUM SALTS, CU-II, COMPLEXES, CHLORIDE",

author = "P Hanson and Rowell, {S C} and Taylor, {A B} and Walton, {P H} and Timms, {A W}",

year = "2002",

doi = "10.1039/b200747a",

language = "English",

pages = "1126--1134",

journal = "JOURNAL OF THE CHEMICAL SOCIETY-PERKIN TRANSACTIONS 2",

issn = "0300-9580",

publisher = "Chemical Society",

number = "6",

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TY - JOUR

T1 - Sandmeyer reactions. Part 6. A mechanistic investigation into the reduction and ligand transfer steps of Sandmeyer cyanation

AU - Hanson, P

AU - Rowell, S C

AU - Taylor, A B

AU - Walton, P H

AU - Timms, A W

PY - 2002

Y1 - 2002

N2 - For Sandmeyer cyanation at 298 K in 50% v/v aqueous acetonitrile buffered at pH 8, absolute rate constants have been obtained for the reduction of 4-methoxybenzenediazonium tetrafluoroborate by the cyanocuprate(I) anions Cu-I(CN)(4)(3-), Cu-I(NCMe)(CN)(3)(2-) and Cu-I(NCMe)(2)(CN)(2)(-) as (0.50 +/- 0.05), (0.12 +/- 0.03) and 0.0 dm(3) mol(-1) s(-1), respectively. The relative reactivity of the two reactive cyanocuprates reflects the estimated difference in their standard reduction potentials. Ligand transfer to the aryl radical from the cyanocuprate(II) anions produced in the reaction occurs within the solvent cage. By use of radical clocks, first order rate constants of the order of 1 x 10(8) s(-)1 for ligand transfer between the caged reactants can be evaluated although the transfer rate may vary from one aryl radical to another. No difference was discerned in ligand transferring reactivity between the two cyanocuprate(II) complexes involved.

AB - For Sandmeyer cyanation at 298 K in 50% v/v aqueous acetonitrile buffered at pH 8, absolute rate constants have been obtained for the reduction of 4-methoxybenzenediazonium tetrafluoroborate by the cyanocuprate(I) anions Cu-I(CN)(4)(3-), Cu-I(NCMe)(CN)(3)(2-) and Cu-I(NCMe)(2)(CN)(2)(-) as (0.50 +/- 0.05), (0.12 +/- 0.03) and 0.0 dm(3) mol(-1) s(-1), respectively. The relative reactivity of the two reactive cyanocuprates reflects the estimated difference in their standard reduction potentials. Ligand transfer to the aryl radical from the cyanocuprate(II) anions produced in the reaction occurs within the solvent cage. By use of radical clocks, first order rate constants of the order of 1 x 10(8) s(-)1 for ligand transfer between the caged reactants can be evaluated although the transfer rate may vary from one aryl radical to another. No difference was discerned in ligand transferring reactivity between the two cyanocuprate(II) complexes involved.

KW - ABSOLUTE RATE CONSTANTS

KW - PSCHORR RADICAL CLOCK

KW - STABILITY-CONSTANTS

KW - ARYL RADICALS

KW - WATER LIGANDS

KW - BENZENEDIAZONIUM IONS

KW - ARENEDIAZONIUM SALTS

KW - CU-II

KW - COMPLEXES

KW - CHLORIDE

U2 - 10.1039/b200747a

DO - 10.1039/b200747a

M3 - Article

SN - 0300-9580

SP - 1126

EP - 1134

JO - JOURNAL OF THE CHEMICAL SOCIETY-PERKIN TRANSACTIONS 2

JF - JOURNAL OF THE CHEMICAL SOCIETY-PERKIN TRANSACTIONS 2

IS - 6

ER -