38689-22-4Relevant academic research and scientific papers
Hypovalent titanium and Ti(II)-Ti(III) interconversions
Dhar, Basab Bijayi,Gould, Edwin S.
, p. 1616 - 1619 (2010)
Treatment of pink titanium(iii) triflate (0.045 M) with HF in triflic acid (CH3SO3H) converts Ti(iii) rapidly to a 1:1 mixture of TiIV and green TiII: (2 TiIII + 4 HF → TiF4 + TiII + 4 H+). This disproportionation is half complete when [HF] added is 0.027 M. Substituted 1,4-benzoquinones are reduced rapidly by Ti(iii) in the absence of fluoride, yielding straightforward logarithmic curves, but reactions of the same quinones with Ti(ii) in fluoride media exhibit more complex profiles, the major portions of which are zero order in oxidant. These reactions are strongly catalyzed by added Ti(iv). Analyses of complex curves are consistent with a reaction sequence initiated by Ti(ii)-Ti(iv) disproportionation, forming Ti(iii), which reacts with the quinone, yielding the quinhydrone, QH. The latter is rapidly reduced by Ti(ii). Values of rate constants obtained from these analyses are in agreement with those for reductions of quinones by Ti(iii), in the absence of fluoride. The Royal Society of Chemistry 2010.
Reductions by aquatitanium(II)
Yang, Zhiyong,Gould, Edwin S.
, p. 1781 - 1784 (2007/10/03)
Solutions of titanium(II), prepared by dissolving titanium wire in mixtures of hydrofluoric and triflic acids, reduce quinones, nitrosodisulfonate anion, and complexes of cobalt(III). When the oxidant is taken in excess, these reactions yield Ti(IV), whereas with excess reductant, the principal product is Ti(III). These reactions are compared with those by Ti(III). Despite differences in rate laws, it is clear that rate ratios for the two reductants (k TiII/kTiIII) fall well below 10 4, the minimum selectivity corresponding to estimated differences in formal potentials, and in some instances, Ti(II), the stronger reductant, reacts more slowly. For both Ti(III) and Ti(II), reductions within the series [Co(NH3)5X]2+ (where X = F, Cl, Br, and I), the fluoro complex reacts much more rapidly than its congeners, and the bromo and iodo complexes are slowest, an order similar to that for Eu2+ reductions, but opposite to that for Cr(II) and Cu(I). The [Co(NH 3)5Br]2+ reaction with excess Ti(II) proceeds at rates very nearly independent of [oxidant] during the first 80-90% reaction, implying that initiation occurs via unimolecular conversion of Ti(II) to an activated cationic reducing species, in the same manner as the earlier described reduction of I3- by Ge(II) in aqueous HCl. The Royal Society of Chemistry 2005.
Reactions of 1,4-benzoquinones with s2 reducing centers
Yang, Zhiyong,Gould, Edwin S.
, p. 2219 - 2223 (2007/10/03)
Aqueous solutions of Sn(II) and Ge(II) (in chloride media) and In(I) (in perchlorate media) react quantitatively with 1,4-benzoquinone and its 2,5-(OH)2 and 2,5-Cl2-3,6-(OH)2 derivatives, reducing the oxo-functions to 1,4-(OH)2. For Sn(II) and Ge(II), reaction is accelerated by incorporation of 2,5-(OH)2 substituents and by chloroanation of the s2 center. The most reactive reducing Sn(II) species are SnCl3- for benzoquinone and dihydroxyquinone but SnCl2(aq)x for the dichloroquinone. Reductions by Ge(II) proceed mainly through a species (probably GeCl 42-) having one more chloride than the predominant form. The activated complex for the (OH)2bzq-Ge(II) reaction features two germanium centers, only one of which is involved in the reduction act. Reductions of these quinones by In(I) proceed 102-103 times as rapidly as those by Sn(II) and Ge(II) and are not accelerated by hydroxylation of the quinone ring. The Royal Society of Chemistry 2003.
