Decalyl radicals

Table 9.2 presents the results of experiments with the 9-decalyl radical, generated as indicated in Scheme 2 from two isomeric precursors.27 In this reaction, the alkyl radicals, which form by fragmentation of the alkoxy radical,... 

Decomposition of the trani-decalyl peroxyester 8-A gives a 9 1 ratio of trans-and di-hydroperoxides at all the oxygen pressures studied. The product ratio from the c/i-peroxyester 8-B is dependent on oxygen pressure. At 1 atm Oj it is 9 1 trans. cis, identical to the trans isomer, but the ratio decreases and eventually inverts with increasing O2 pressure. At 545 atm, the ratio is 7 3, favoring the cii-hydroperoxide. What deductions about the stereochemistry of the 9-decalyl radical can be made from these observations ... 

Somewhat surprisingly, the cis-9-decalyl radical can be efficiently trapped by 0.5 M perbenzoic acid at 100 °C. Reaction of perbenzoic acid with decalin is presumed to proceed according to Scheme 11. Table 13 summarizes pertinent data for this reaction. 

Class (3) reactions include proton-transfer reactions of solvent holes in cyclohexane and methylcyclohexane [71,74,75]. The corresponding rate constants are 10-30% of the fastest class (1) reactions. Class (4) reactions include proton-transfer reactions in trans-decalin and cis-trans decalin mixtures [77]. Proton transfer from the decalin hole to aliphatic alcohol results in the formation of a C-centered decalyl radical. The proton affinity of this radical is comparable to that of a single alcohol molecule. However, it is less than the proton affinity of an alcohol dimer. Consequently, a complex of the radical cation and alcohol monomer is relatively stable toward proton transfer when such a complex encounters a second alcohol molecule, the radical cation rapidly deprotonates. Metastable complexes with natural lifetimes between 24 nsec (2-propanol) and 90 nsec (tert-butanol) were observed in liquid cis- and tra 5-decalins at 25°C [77]. The rate of the complexation is one-half of that for class (1) reactions the overall decay rate is limited by slow proton transfer in the 1 1 complex. The rate constant of unimolecular decay is (5-10) x 10 sec for primary alcohols, bimolecular decay via proton transfer to the alcohol dimer prevails. Only for secondary and ternary alcohols is the equilibrium reached sufficiently slowly that it can be observed at 25 °C on a time scale of > 10 nsec. There is a striking similarity between the formation of alcohol complexes with the solvent holes (in decalins) and solvent anions (in sc CO2). 

One possible interpretation of these results is that the two tertiary decalyl radicals react differendy because they are pyramidal (8 and 9) on the other hand, the hypothesis that the radicals are planar and differ only in ring con-... 

Figure 2 shows a pathway for DHN pyrolysis. In this case there is appreciably greater complexity than for CYH because all three types of decalyl radicals shown are possible and each admits of a variety of decomposition routes. We show one particular pathway leading from the... 

In 1944 Criegee observed that trans-9-decalyl peroxyesters rearrange on standing to 1,6-epoxycyclodecyl esters.172 Further study of the reaction showed that it has the characteristics of an ionic rather than a radical pathway The rate is... 

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