Hexyl-3 hydroperoxide

Hexyl-1 hydroperoxide nQHi3-OOH 70.1 293.3 Derived from AfH° in ref. 1969BDE/CRU... 

Chlorophenyl)-l,l-dimethylethyl hydroperoxide, 3018 2-Cyclohexenyl hydroperoxide, 2435 1,1-Dichloroethyl hydroperoxide, 0794 3,5-Dimethyl-3-hexyl hydroperoxide, 3075 Ethyl hydroperoxide, 0925... 

Hexenoic acid, see 1-Hexene 5-Hexen-l-ol, see 1-Hexene Hexyl hydroperoxide, see Hexane Hexyl nitrate, see 2,3-Dimethylbutane, Hexane, 2-Methylpentane... 

Methoxy- carbonyl) pentyl 1 -Methoxycyolo-hexyl hydroperoxide l,c... 

The enthalpy of formation data appear in Table 1. Where there are numerous data for structurally related compounds, plotting the enthalpy of formation versus the number of carbons can reveal at a glance the quality of the data. For the alkyl hydroperoxides especially, the data are seen to be of mixed quality as evidenced by the lack of linearity in the plot (Figure 1). The error bars for the ethyl and n-propyl hydroperoxides are so large as to render the data meaningless. Also, the enthalpy of formation of n-propyl hydroperoxide is more negative than that of 1-hexyl hydroperoxide, another indication of its gross inaccuracy. The C2 and C3 hydroperoxide data will not be considered any further. 

The enthalpy of isomerization of hquid 1-hexanol to either 2- or 3-hexanol is ca 15 kJ mol , and the enthalpy of isomerization of hquid 1 -heptanol to 2-, 3- or 4-heptanol is ca 13 kJ mol . From the experimental enthalpy of formation of 1 -hexyl hydroperoxide, the calculated enthalpy of formation of 2- and 3-hexyl hydroperoxide is ca —315 kJ moU , which is about 5-10 kJmoU more negative than their experimental values. As noted earlier, the measured enthalpies of formation of 2- and 3-heptyl hydroperoxide are about the same as that of 1-heptyl hydroperoxide, while that of 4-heptyl hydroperoxide is actually less negative than for its primary isomer. Using instead the above-derived enthalpy of formation of 1-heptyl hydroperoxide of —325 kJmoU , the enthalpy of formation of the secondary isomers would be ca —338 kJ moU. This value is very close to the experimental enthalpy of formation of 4-heptyl hydroperoxide, but 8 kJmoU less negative than the experimental values for 2- and 3-heptyl hydroperoxide. These latter enthalpies of formation are too negative compared to the experimental values for 2- and 3-hexyl hydroperoxide, with a methylene increment of ca 36 kJ mol . The derived values are more plausible. 

For the formal deoxygenation (decomposition) reaction 5, there is an enthalpy of formation value for every alcohol that matches a hydroperoxide . Using our exemplary groups, R = 1-hexyl, cyclohexyl and ferf-butyl, the liquid enthalpies of reaction are —77.9, —75.0 and —65.6 kJmoR, respectively (there is no liquid phase enthalpy of formation reported for f-butyl peroxide from Reference 4). The secondary hydroperoxides enthalpies of reaction average —77 7 kJmoR. For the three instances where there are also gas phase enthalpies of formation, the enthalpies of reaction are almost identical in the gas and liquid phases. The 1-heptyl (—60.3 kJmoR ) and 1-methylcyclohexyl (—50.6 kJmoR ) enthalpies of reaction are again disparate from the 1-hexyl and tert-butyl. If the enthalpy of reaction 5 for 1-hexyl hydroperoxide is used to calculate an enthalpy of formation of 1-heptyl hydroperoxide, it is —325 kJmoR, almost identical to values derived for it above. The enthalpies of reaction for the liquid and gaseous phases for the tertiary 2-hydroperoxy-2-methylhex-5-en-3-yne are —78.2 and —80.9 kJmoR, respectively. For gaseous cumyl hydroperoxide, the enthalpy of reaction is —84.5 kJmoR. ... 

The liquid enthalpy of formation difference between 1-hexyl and 1-heptyl hydroperoxides is almost twice that of a normal enthalpy of formation methylene increment of about 25 kJmol . But which of these two, if either, is correct For hydrocarbon snb-stituents bonded to electronegative functional groups, the secondary isomers are more stable than the n-isomer. Accordingly, either the 1- or 4-heptyl hydroperoxide, or both, have an inaccurate enthalpy of formation because the primary isomer is reported to have the more negative enthalpy of formation. All of the enthalpies of formation for the Cg and C7 hydroperoxides cited in Reference 2 come from a single source. There is a reported value for the gas phase enthalpy of formation of fert-butyl hydroperoxide that is 11 kJ mol less negative than the value in Reference 2. 

For reaction 3 to replace an oxygen with a methylene group to form a primary alcohol, there are enthalpies of formation for only seven alcohols to compare with the nineteen hydroperoxides, almost all of them only for the liquid phase. The enthalpies of the formal reaction are nearly identical, —104.8 1.1 kJmol, for R= 1-hexyl, cyclohexyl and ferf-butyl, while we acknowledge the experimental uncertainties of 8.4 and 16.7 kJmol, respectively, for the enthalpies of formation of the secondary and tertiary alcohols. We accept this mean value as representative of the reaction. For R = 1- and 2-heptyl, the enthalpies of reaction are the disparate —83.5 and —86.0 kJmol, respectively. From the consensus enthalpy of reaction and the enthalpy of formation of 1-octanol, the enthalpy of formation of 1-heptyl hydroperoxide is calculated to be ca —322 kJ mol, nearly identical to that derived earlier from the linear regression equation. The similarly derived enthalpy of formation of 3-heptyl hydroperoxide is ca —328 kJmol. The enthalpy of reaction for R = i-Pr is only ca —91 kJmol, and also suggests that there might be some inaccuracy in its previously derived enthalpy of formation. Using the consensus enthalpy of reaction, a new estimate of the liquid enthalpy of formation of i-PrOOH is ca —230 kJmoU. ... 

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