Dialkyl peroxides hydroperoxide determination

As was the case for the alkyl hydroperoxides in reaction 4, the enthalpies of the oxy-gen/hydrocarbon double exchange reaction 8 for dialkyl peroxides are different depending on the classification of the carbon bonded to oxygen. For R = Me, Et and f-Bu, the liquid phase values are —4, 24.6 and 52.7 kJmoR, respectively, and the gas phase values are 0.1, 25.7 and 56.5 kJmoR, respectively. For the formal deoxygenation reaction 9, the enthalpies of reaction are virtually the same for dimethyl and diethyl peroxide in the gas phase, —58.5 0.6 kJ moR. This value is the same as the enthalpy of reaction of diethyl peroxide in the liquid phase, —56.0 kJ moR (there is no directly determined liquid phase enthalpy of formation of dimethyl ether). Because of steric strain in the di-ferf-butyl ether, the enthalpy of reaction is much less negative, but still exothermic, —17.7 kJmol (Iq) and —19.6 kJmol (g). 

The HPLC method with CLD described in Section V.B.2.C for determination of hydroperoxides using luminol (124) with hemin (75a) catalysis is ineffective with dialkyl peroxides, such as di-f-butyl peroxide, cumyl propyl peroxide and cumyl 3-phenylpropyl peroxide. However, for a certain set of experimental conditions, cumyl aUyl peroxide can be determined, but the sensitivity is much lower than for hydroperoxides . ... 

Dialkyl peroxides (continued) colorimetry, 707-8 flame ionization detection, 708 NMR spectroscopy, 708 titration methods, 707 UV-visible spectrophotometry, 707-8 enthalpies of reactions, 153-4 graft polymerization initiation, 706 hydroperoxide determination, 685 peroxide transfer synthesis, 824-5 stmctural characterization, 708-16 electrochemical analysis, 715-16 electron diffraction, 713 mass spectrometry, 714 NMR spectroscopy, 709-11 thermal analysis, 714-15 vibrational spectra, 713-14 X-ray crystallography, 711-13 synthesis... 

DEPT technique, 725 -6 dialkyl peroxide determination, 708 Eourier transform, 695 hydroperoxides... 

Our laboratory oxidations were carried out by bubbling dry air at 80 to 125 cc. per minute STP, at 110°C. through 500 ml. of olefin in a round-bottomed, 1-liter, standard-taper, three-necked flask equipped with magnetic stirrer, Therm-O-watch controller, electric heating mantle, and condenser. Alkenyl hydroperoxide numbers [Method I of Mair and Graupner (11)] and polymeric dialkyl peroxide numbers (Method III minus Method I of Ref. 11) were determined on small aliquots of about 5 ml. withdrawn at various times. 

The alkenyl hydroperoxides and polymeric dialkyl peroxides are fairly stable at ambient temperature but decompose appreciably at the reaction temperatures studied. Thermal stabilities of the alkenyl hydroperoxides and dialkyl peroxides in the olefin solution were determined by heating the solution at 110°C. under nitrogen. The peroxide numbers were plotted vs. time to estimate the half-lives in solution. The thermal decomposition half-lives of these alkenyl hydroperoxides are compared with values from the literature for acyclic and cyclic hydroperoxides in Table IV. Secondary acyclic alkenyl hydroperoxides appear to be less... 

Applications The Karl Fischer reagent can be applied directly to the determination of water in a variety of organic compoimds, including saturated or unsaturated hydrocarbons, alcohols, halides, acids, acid anhydrides, esters, ethers, amines, amides, nitroso and nitro compounds, sulfides, hydroperoxides, and dialkyl peroxides. The use of sodium tartrate dihydrate for standardization of the response of the Karl Fischer reagent has been shown to lead to a small error because of occlusion of about 2% (relative) water in the crystal structure. 

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