Radicals footnote

The reaction fails if the decarboxylation produces a radical that is easily oxidized, such as an a-hydroxyalkyl radical.2 In intermediate cases, such as tert-alkyl or a-alkoxyalkyl radicals,2 the yield based on the parent quinono is usually improved by using an excess of persulfate and carboxylic acid to compensate for the loss of radicals due to oxidation (footnote b, Table I). 

The data from Beckwith s work given in Table 10-9 look very confusing but, as discussed in the four papers by Beckwith s group (see footnote a) in Table 10-9) and in additional comments in Galli s review (1988), they can all be explained on the basis of our present knowledge of aryl radical chemistry, with the exception of the endo cyclization of the 2-(7V-2,-propenylsulfamoyl)-benzenediazonium ion in Scheme 10-81. 

The sequence of reactions (58) and (59) corresponds to the mechanism proposed for chain transfer with benzene (see p. 142, footnote). The experimental result of Price and Read does not, however, rule out the possibility that the inhibitor radical (e.g., IV, or a possible successor formed by intramolecular rearrangement) may occasionally add monomer, thus giving rise to limited copolymerization of the retarder. 

In these solutions, the hydrated electrons from the radiolysis of water produce CO by their reaction with COj, and the OH radicals attack the alcohol to form (CHjIjCOH radicals (see also footnote on page 117). 

In this paper the rate expressions have all been corrected for nitrogen evolution from the azo initiator, oxygen absorption by initiator radicals, and oxygen evolution in termination. It is assumed that the initiator which decomposes without starting oxidation chains does not react with oxygen (21). This correction involves the addition of (l-e)Ri/2e to the measured rate, where e is the efficiency of chain initiation, found to be 0.5 at 30 °C. and 0.6 at 56 °C. The rate constant for Reaction 7 has been written as 4ktCT in order that the three termination constants may be comparable (26, footnote 27).]... 

Besides the similarities between CF3S and chlorine already given in footnote 1, new examples have been found to substantiate the parachlorine behavior of the CF3S radical. 

The LB films of TTF [73,74] and BEDT-TTF [75-81] derivatives were investigated and secondary treatments, such as iodine or ICI doping, rendered the films conductive. The structure of the LB film of C18TET-TTF doped with iodine is investigated by UV/visible and IR spectroscopies [76— 79]. The initial stage of the chemical reaction involves formation of the cation radical of the donor, which is converted spontaneously into a dimeric form. At this step the film is insulating. Gradual evaporation of I2 from the film takes place afterward and the conductivity of the film reaches a maximum of about 0.1 S/cm. (See the footnote in Section II.A. 1.)... 

Table XII.5 is a compilation of some of the data on reactions that involve the attack of atoms on molecules or radicals. In most of the cases the data have been taken directly from the original authors and transformed into the form of the collision equation, when not already in that form. In some cases the rate constant for a reverse process has been calculated from that of the forward reaction and thermodynamic data for the equilibrium. Where that has been done the footnotes will so indicate The steric factors shown in the last columns have been calculated on the basis of an arbitrary collision diameter o- which is indicated in parentheses. It is quite evident that the steric factors so calculated cannot be literally interpreted, since variations within a factor of 3 could equally well have been obtained by using different but equally justifiable cross sections.

All values for rate constants k are calculated from the relation k = Rkst where R is an observed quantity and ks is the rate constant for the recombination of methyl radicals, llie value used here is from Gomer and Kistiakowsky (see Table XII.5, footnote e). The E listed is in reality E — HEb, and we have taken Eb = 0. For the reactions of CDs we have assumed that fcs = (mb/mb ) = 0.91fcB> or Jcb = 0.96. ... 

Table XII.4, footnote /. The above constants are calculated only for data below 40°C, since the radical chain becomes important at high temperatures. AH° = —9.0 Kcal/mole NOCl - —14.0 cal/mole- C. These values can be used to calculate the reverse reaction rate.

Gerson and co-workers" " " some years ago reported an analysis of the ESR spectrum of the anion-radical 233 of 2,5-diphenyl[l,2,4]dithiazolo-[l,5-fe][l,2,4]dithiazole. Some of the work reported at the same time concerning anion-radicals of analogous 6a-thiathiophthenes was subsequently reinterpreted." " However, the inference from footnote 7 in Gerson et al. is that the results for 233 are not superseded. (Hyperfine splittings indicated for 233 are in gauss.)... 

Footnote A Ketones are derived from the fatty acids by the substitution of the hydroxyl of the latter by a monad positive radical. They thus resemble aldehydes in constitution. The best-known ketone is acetone CH 3 CO.CH 3. Mixed ketones are obtained by distilling together salts of two different fatty acids. Thus potassic butyrate and potassic acetate form propyl-methyl-ketone-... 

Most importantly, Wurtz asserted that the main lines of Couper s theory were not, despite his protestations, irreconcilable with either radical or type theory, considering especially the most recent modifications of those theories. "In general," he wrote, "1 find M. Couper s formulas too arbitrary, too distant from experiment." Rational formulas are not intended to show the "intimate constitution of compounds," only reactions "hence their advantage." In sum "It is too much of hypotheses, and it is wrong to present these things as if they were handed down by God. In this respect M. Kekule, who seems better to have understood the sense and import of the ideas which he was the first to express, wisely wrote at the end of his memoir, As for me, I attach but a secondary importance to considerations of this sort. " Wurtz failed to take this opportunity to affirm that he had Couper s paper in hand at the time Kekule s second theoretical paper was published. In several subsequent historical accounts of the rise of structure theory, Wurtz mentioned Couper s independent formulation only once, and that in a footnote. It does appear that Wurtz and Couper had clashed personally, and this may have ever after influenced Wurtz s treatment of his former student. His reticence fully to acknowledge Couper s substantial accomplishment is out of character for Wurtz s notably wise and generous personality. 

Only compounds with unambiguously verified or at least very plausible structures are included. Papers which only state the presence of free radicals in a sample and do not give detailed structures nor magnetic properties of the radicals have not been reviewed. Also not reviewed are papers which deal exclusively with other topics than experimental determinations of magnetic properties of free radicals. Such papers may however be mentioned in footnotes or as further references at the appropriate entries. 

The first column describes the structure of the radical and contains the gross formula, the name (where useful and appropriate) and the structural formula (or a footnote referring to the structural formula). 

Radicals have only been included if their structures seemed to be at least fairly well established. Footnotes hint to tentative identifications. Also, a large number of individual papers on free radicals which give only very rough data on magnetic properties were not included if the particular data were more accurately known from other references. 

Gomberg 1928,164. In his monograph on philosophy of chemistry, the Dutch philosopher Jaap van Brakel refers to a similar view. In a footnote referring to discussions of USSR philosophers of chemistry such as Kedrov he states Here, the material carriers of chemical change are assumed to be atoms, molecules, radicals and ions (both of atoms and atom groups) , van Brakel 2000, 25. Note that in fact any analytical work incorporates necessary synthetic steps, that is, the analytical methodology like in Schummer s description should be read theoretically rather than empirically. 

---