How Solvent Modulates Hydroxyl Radical Reactivity in Hydrogen Atom Abstractions

Abstract:: Minisci-type reactions have become widely known as reactions that involve the addition of carbon-centered radicals to basic heteroarenes followed by formal hydrogen atom loss. While the originally developed protocols for radical generation remain in active use today, in recent years by a new array of radical generation strategies allow use of a wider variety of radical precursors that often operate under milder and more benign conditions. New transformations based on free radical reactivity are now available to a synthetic chemist looking to utilize a Minisci-type reaction. Radical-generation methods based on photoredox catalysis and electrochemistry, which utilize thermal cleavage or the in situ generation of reactive radical precursors, have become popular approaches. Our review will cover the remarkably literature that has appeared on this topic in recent 5 years, from 2015-01 to 2020-01, in an attempt to provide guidance to the synthetic chemist, on both the challenges that have been overcome and applications in organic synthesis.

Download Full-text

Radiolysis studies on the corrosion inhibitors 1 -hexyn-3-ol, cinnamonitrile, and 1,3-diethyl-2-thiourea

Canadian Journal of Chemistry ◽

10.1139/v95-264 ◽

1995 ◽

Vol 73 (12) ◽

pp. 2137-2142 ◽

Cited By ~ 1

Author(s):

A.J. Elliot ◽

M.P. Chenier ◽

D.C. Ouellette

Keyword(s):

Hydrogen Atom ◽

Hydroxyl Radical ◽

Temperature Dependence ◽

Rate Constant ◽

Rate Constants ◽

Corrosion Inhibitors ◽

Hydrated Electron

In this publication we report: (i) the rate constants for reaction of the hydrated electron with 1-hexyn-3-ol ((8.6 ± 0.3) × 108 dm3 mol−1 s−1 at 18 °C), cinnamonitrile ((2.3 ± 0.2) × 1010 dm3 mol−1 s−1 at 20 °C), and 1,3-diethyl-2-thiourea ((3.5 ± 0.3) × 108 dm3 mol−1 s−1 at 22 °C). For cinnamonitrile and diethylthiourea, the temperature dependence up to 200 °C and 150 °C, respectively, is also reported; (ii) the rate constants for the reaction of the hydroxyl radical with 1-hexyn-3-ol ((5.5 ± 0.5) × 109 dm3 mol−1 s−1 at 20 °C), cinnamonitrile ((9.2 ± 0.3) × 109 dm3 mol−1 s−1 at 21 °C), and diethylthiourea ((8.0 ± 0.8) × 108 dm3 mol−1 s−1 at 22 °C). For cinnamonitrile, the temperature dependence up to 200 °C is also reported; (iii) the rate constant for the hydrogen atom reacting with 1-hexyn-3-ol ((4.3 ± 0.4) × 109 dm3 mol−1 s−1 at 20 °C). Keywords: radiolysis, corrosion inhibitors, rate constants.

Download Full-text

Reactivity of Oxygen Radicals [HO•, RO•, HOO•, ROO-, and RC(O)O•]

Oxygen Chemistry ◽

10.1093/oso/9780195057980.003.0009 ◽

1992 ◽

Author(s):

Donald T. Sawyer ◽

R. J. P. Williams

Keyword(s):

Oxygen Atom ◽

Hydroxyl Radical ◽

Gas Phase ◽

Oxygen Radicals ◽

Oxygen Radical ◽

Superoxide Ion ◽

Radical Reactivity ◽

The Family ◽

Hydrocarbon Substrates

Oxygen radicals are defined as those molecules that contain an oxygen atom with an unpaired, nonbonding electron (e.g., HO·). Although triplet dioxygen (·O2·) and superoxide ion (O2 - ·) come under this definition, their nonradical chemistry dominates their reactivity, which is discussed in Chapters 6 (·O2·) and 7 (O2-·). The hydroxyl radical (HO·) is the most reactive member of the family of oxygen radicals [HO·, RO·, ·O·, HOO·, ROO·, and RC(O)O·], and is the focus of most oxygen radical research. In the gas phase the dramatic example of oxygen radical reactivity with hydrocarbon substrates is combustion, which is initiated by HO· (or RO· or MO·) and propagated by ·O2· and ·O·.

Download Full-text