Hydron donor

As this book was going to press the International Uraon of Pure and Applied Chemistry recommended that (he word proton be used only when the H isotope was intended, and that ihc more general Irydron be used everywhere dsc, as in hydron donor. See Appendix t. Section 8. We have not attempted a) the last minute to change ail of these "protons to hydrons Like the SI system of units, (his change, if accepted by the world s chemsts. wtl take some lime, and the term "proton donor wil not soon disappear. 

This is a new recommendation. Note that it implies that all uses with respect to acids and bases involving tbe normal isotopic mixture of h. 2H. and 3H would require the use of hydron, i.c., the hydron affinity of bases, Brpnsied acids are hydron donors, etc. Wc have retained the current usage of proton affinity, etc., because the recommendation came out as this book was going to press. The reader should note however that hydron is already receiving some European usage, as in "GS = GSH dehydronated at the thiol group."]... 

Scheme 1 Catalase mechanism showing schematically the bis(carboxylato) bridged dinuclear metal centers. DH/Dy hydron donor/acceptor species. (After Refs. 7, 96.)...

For Bronsted acids, acidity refers to the tendency of a compound to act as a hydron donor. It can be quantitatively expressed by the acid dissociation con-... 

Bronsted acid (Bronsted-Lowry acid) A molecular entity capable of donating a hydron to a base (i.e., a hydron donor ) or the corresponding chemical species. For example H20, H30+, CH3C02H, H2SC>4, HSO4-, HC1, CH3OH, and NH3. 

SolvH" represents a hydron donor such as water, ammonia or an alcohol, and "Solv-Na+" its sodium salt.) Attractive features of the use of sodium to destroy chemical warfare agents are mentioned in the poster abstracts of Sokolowski and Bilger and of Bunnett (this volume). A potential problem is that adventitious acids that might somehow mix with the products will convert sodium arsenide (Na3As) to the extremely toxic arsine (ASH3). Conversion of Na3As to a much less toxic arsenic compound should immediately follow the sodium treatment. 

Protogenic Capable of acting as a proton (hydron) donor strongly or weakly acidic (as a Bronsted acid). The term is preferred to the synonym protic or the more ambiguous expression acidic by itself. Also called HBD (hydrogen-bond donor) solvent. ... 

Figure 5 Proposed catalytic cycle of MCR. Methyl CoM binds first to the active site pocket, followed by CoB, which plugs the channel. The methyl group is transferred from CoM to nickel (step 1). The donor for the hydron that is taken up is suggested here to be a tyrosyl residue in the active site. The Ni(III)-methyl group is a strong oxidizing species and oxidizes the CoM-SH to a thiyl radical CoM-S" (step 2). Release of the methyl group takes place by hydronation of the methyl-Ni(II), while the CoM forms a disulfide with CoB, with electron transfer to the Ni(I) these two processes are combined in step 3. Repulsion of the sulfonate group by the Ni(I) would favor the release of the product disulfide from the active site (step 4). (Adapted from Ref. 119.)...

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