1 -Octen-3 -hydroperoxide

Figure 7. Reaction routes proposed for the formation of 1-octen-3-hydroperoxide (R= CH2 (CH2)4 ) and cis-1,5-octadien-3-hydroperoxide fCHs-- CH2- CH= CH CH2) (13).

Heptachloro-3a,4,7,7a-tetrahydro-4,7-methano-l/7-indene see Chlordane Heptachlor triol, see Heptachlor epoxide Heptanal, see Heptane. 1-Octene 1-Fleptanol. see Heptane Heptanoic acid, see Heptane 1-Fleptene. see Heptane Heptyl hydroperoxide, see Heptane Hexachlorobenzene, see Hexachlorobutadiene,... 

Olefin epoxidation is an important industrial domain. The general approach of SOMC in this large area was to understand better the elementary steps of this reaction catalyzed by silica-supported titanium complexes, to identify precisely reaction intermediates and to explain catalyst deachvahon and titanium lixiviation that take place in the industrial Shell SMPO (styrene monomer propylene oxide) process [73]. (=SiO) Ti(OCap)4 (OCap=OR, OSiRs, OR R = hydrocarbyl) supported on MCM-41 have been evaluated as catalysts for 1-octene epoxidation by tert-butyl hydroperoxide (TBHP). Initial activity, selechvity and chemical evolution have been followed. In all cases the major product is 1,2-epoxyoctane, the diol corresponding to hydrolysis never being detected. 

Co and Cu exchanged X and Y zeolites catalyze the decomposition of t-butyl hydroperoxide with generation of t-butoxy and t-butylperoxy radicals. When this decomposition is performed in the presence of olefins, such as cyclohexene or 1-octene, the corresponding epoxides are formed with selectivities ranging from 10 to 50% based on decomposed t-butyl hydroperoxide... 

Substantial alkenyl hydroperoxide concentrations build up in 1-hexa-decene, 2-octene, mixed internal olefins, and mixed Ci4-Ci6 alpha-olefins... 

Procedures. Chromatographic Purification of Ozonization Products. Ozonization products from ethyl 10-undecenoate and 1-octene were chromatographed on silica gel columns (Baker) and eluted with 15 or 25% ether in petroleum ether (b.p., 30°-60°). Fractions were examined by thin-layer chromatography (TLC) on silica gel G Chroma-gram sheet eluted with 40% ether in petroleum ether. For development of ozonide and peroxide spots, 3% KI in 1% aqueous acetic acid spray was better than iodine. The spots (of iodine) faded, but a permanent record was made by Xerox copying. Color of die spots varied from light brown (ozonide) to purple-brown (hydroperoxide), and the rate of development of this color was related to structure (diperoxide > hydroperoxide > ozonide). 2,4-Dinitrophenylhydrazine spray revealed aldehyde spots and also reacted with ozonides and hydroperoxides. Fractions were evaporated at room temperature or below in a rotary evaporator. 

Isothermal Calorimetry of Hexanitratoammonium Cerate Oxidation of Products from 1-Octene and 10-Undecenoic Acid. The heat developed in the oxidation of ethyl 10-ethoxydecanoate 10-hydroperoxide in ethanol is shown in Figure 1. Samples of 10% solutions of peroxide in ethanol were used with 5-ml. aliquots of 0.1465N cerate in 25 ml. of ethanol. The intersection of the two lines shows a ratio of 1.04 moles of peroxide per equivalent of cerium and maximum heat evolution of 42 kcal. per equivalent of cerium. Similar plots were made for the reaction of the corresponding methoxyhydroperoxide in ethanol (1.10 equivalents, 47 kcal.) and in methanol (1.08 equivalents, 45 kcal.). 1-Ethoxyheptane-1-hydroperoxide was oxidized in acetone (0.98 equivalent, 36 kcal.), in... 

Compounds 16 and 19 each deliver the expected six alcohols after reduction of the primarily formed hydroperoxide mixtures as a result of an oxygen attack on the trisubstituted A1 double bonds of these molecules. The ratio of tertiary/secondary hydroperoxides (or alcohols) is about 44 56, as has also been found with 1-methylcyclohexene (30)13S while open-chain olefins such as trimethylethylene (S3), 1,1-dimethyl-2-ethylethylene (id), 2,6-dimethyl-2-octene (39), myrcene (42), / -citronellol (45), linalool (48), and l,l-dimethyl-2-benzylethylene (51) give ratios of tertiary/secondary hydroperoxides between 54 46 and 60 40.104-1 7 7 1 79 The slight deviations from 1 1 ratios in all these cases are probably due to stereochemical rather than electronic effects exerted by the olefins on the reaction with oxygen. 

Unsaturated fatty acids also seem to undergo oxidative breakdown during cooking. The volatile compounds found in cooked products are generally the same as in the raw product. Frequently there are, however, quantitative differences between the cooked and the raw product. Flowever, not much is known about the thermal fatty acid breakdown, but possibly it involves decomposition of already formed hydroperoxides in the raw product and/or oxidation of already formed volatile compounds. For example, l-octen-3-ol occurs in raw cut mushroom, whereas l-octen-3-one cannot be detected. On the other hand, l-octen-3-one is found in relatively large amounts in cooked mushroom [26]. 

Epoxyoctane. A solution of 1 gram of f erf-butyl hydroperoxide (97% purity), 3 ml. of octene-1, 3 ml. of benzene, and 0.005 gram of molybdenum hexacarbonyl was sealed in a pressure tube and allowed to react for 1 hr. in a constant temperature bath at 90°C. The tube was removed and cooled in ice water. Hydroperoxide and epoxide were analyzed by iodometric titration and GLC. There was a 75% conversion of the hydroperoxide and a 92% yield of the epoxide based on the hydroperoxide conversion. 

Effect of Olefin Structure. The reaction rate of the epoxidation depends on olefin structure. In general, the more alkyl substituents bonded to the carbon atoms of the double bond, the faster the reaction rate. This was shown by a reaction of 2-methyl-2-pentene, cyclohexene, and 2-octene with cumene hydroperoxide under the same conditions (Table V). The yield of epoxide was quantitative. The results indicate that 2-methyl-2-pentene reacts faster than cyclohexene and 2-octene. 

In another series of experiments, 1-octene, 2-octene, and cyclohexene reacted with f erf-butyl hydroperoxide under identical conditions (Table VI). The yield of epoxide was quantitative. 

Effect of Hydroperoxide Structure. The reactivity of various hydroperoxides was studied with 2-octene and 2-methyl-l-pentene (Table VII). The yield of epoxide was quantiative. The data show that the substitution of the electron-withdrawing nitro groups in the para-position of cumene hydroperoxide markedly increases the reaction rate. The order of reactivity is p-nitrocumene > cumene > tert-butyl hydroperoxide. 

The decomposition rate of tert-butyl hydroperoxide is much slower than the epoxidation rate. When tert-butyl hydroperoxide and molybdenum hexacarbonyl are refluxed in a mixture of toluene and benzene at 87°C. for 1 hr., only 6.2% of the hydroperoxide decomposes. Under the same conditions with 2-octene present in large excess, 80% of the hydroperoxide is converted, and a quantitative yield of the epoxide results. Thus, the decomposition of tert-butyl hydroperoxide is insignificant when the olefin is present. 

The order with respect to olefin was determined by experiments with 2-octene and tert-butyl hydroperoxide in benzene. The mole ratio of reactants was 1.5 to 1 and 2 to 1. The first-order plot of log Ctert-buooh... 

Figure 3. Second-order plot for the epoxida-tion of 2-octene at 79°C. Mole ratio of tert-butyl hydroperoxide 2-octene = 1 2(0) ana 1 1.5 (O)...

Conducting the same experiment using tril-inolein produced volatiles unique to the trili-nolein substrate, with the major classes being alkanals, 2-alkenals, 2,4-alkadienals, and hydrocarbons. Those volatiles, produced uniquely from this substrate and attributable to the breakdown of 9- and 13-hydroperoxides, include pentane, pentanal, 1 -pentanol, hexanal, 2-hexenal, 3-hexenal, 2-heptenal, 2-octenal, 2,4-decadienal, and acrolein. Addition of triolein afforded the added production of volatiles previously identified in triolein alone, but ad-... 

From these considerations, the synthesis of silsesquioxanes was optimised, by means of HTE, as a function of the activity of the catalysts obtained after titanium coordination to the silsesquioxane structures. Therefore, this approach aimed at producing any incompletely condensed silsesquioxane that would result in active catalysts after titanium coordination rather than a specific structure (like silsesquioxane ulhS). The epoxidation of 1-octene with tert-butyl hydroperoxide (TBHP) as the oxidant was chosen as test reaction for the activity of the catalysts [26]. 

A new parameter space for the synthesis of silsesquioxane precursors was defined by six different trichlorosilanes (R=cyclohexyl, cyclopentyl, phenyl, methyl, ethyl and tert-butyl) and three highly polar solvents [dimethyl sulfoxide (DMSO), water and formamide]. This parameter space was screened as a function of the activity in the epoxidation of 1-octene with tert-butyl hydroperoxide (TBHP) [26] displayed by the catalysts obtained after coordination of Ti(OBu)4 to the silsesquioxane structures. Fig. 9.4 shows the relative activities of the titanium silsesquioxanes together with those of the titanium silsesquioxanes obtained from silsesquioxanes synthesised in acetonitrile. The values are normalised to the activity of the complex obtained by reacting Ti(OBu)4 with the pure cyclopentyl silsesquioxane o7b3 [(c-C5H9)7Si7012Ti0C4H9]. 

Further evidence against initiation by direct oxygen activation in the oxidation of olefins is provided by the following two observations.185 First, no reaction was observed between olefins (e.g., cyclohexene, 1-octene, and styrene) and metal-dioxygen complexes, such as I, II, and V, when they were heated in an inert atmosphere (nitrogen). Second, no catalysis was observed with these metal complexes in the autoxidation of olefins, such as styrene, that cannot form hydroperoxides. 

Hexanal and 2,4-decadienal are the primary oxidation products of linoleate. The autoxidation of linoleate generates 9- and 13-hydroperoxides of linoleate. Cleavage of 13-hydroperoxide will lead to hexanal and breakdown of 9-hydroperoxide will lead to 2,4-decadienal (9). Subsequent moisture-mediated retro-aldol reaction of 2,4-decadienal will produce 2-octenal, hexanal, and acetaldehyde (10). 2,4-Deca-dienal is known to be one of the most important flavor contributors to deep-fat fried foods (11). 

Ketones Aliphatic ketones formed by autoxidation of lipids also contribute to the flavor of oils and food products. For example, Guth and Grosch (13) identified l-octen-3-one as one of the odor-active compounds in reverted soybean oil. This compound was described as metallic and mushroom-like. The reaction pathway for the formation of l-octen-3-one from the linoleate-10-hydroperoxide via the p-scission route is illustrated in Figure 2. 10-Hydroperoxide of linoleate is not the usual hydroperoxide formed by autoxidation of linoleate however, it is one of the major hydroperoxides formed by the photosensitized oxidation (singlet oxygen reaction) of linoleate (14). 

Figure 2. Mechanism for the formation of 1-octen-3-one from 10-hydroperoxide of linoleate.

Alcohols and Other Compounds Cleavage of lipid hydroperoxides wUl also lead to alcohols, alkanes, alkenes, and alkynes. The mechanism for the formation of l-octen-3-ol, which has a strong mushroom flavor, is also shown in Figure 2. Because of their relative high odor threshold, alcohols and hydrocarbons are generally not considered to be important contributors to the flavors of fats and oils and lipid-containing foods. 

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