Hexane, from 1-hexene

We had previously determined isotopic distribution patterns for alkanes derived from the deuterogenation of several olefins on an amorphous catalyst activated to 300° in hydrogen followed by activation in nitrogen to 470° (52). For reactions at about 60°, the patterns for the alkanes from j)ropylene, 1-butene, cyclopentene, and 1-hexene closely resemble those obtained for hexane from 1-hexene on amorphous catalysts in the present work that for pentane from 2-pentene resembles that for hexane from lower selectivity for alkane-d2. We consider it important that the previous work showed that ethylene led to no ethane containing more than two deuterium atoms. In the previous investigation, the effect of the temperature of... 

To do so, one can take the enthalpy of formation of n -hexane from Pedley, and with the phase independence assumptions in Reference 7, employ the enthalpies of hydrogenation of 1-hexene and 1,5-hexadiene from References 11 and 12 respectively. Alternatively13, one can forget about the first quantity altogether and simply take the difference of the enthalpies of hydrogenation of the diene and twice that of the monoene. This reaction is endothermic by 1.1 1.8 kJ mol-1, a value statistically indistinguishable from the absence of any interolefin interaction in the diene. Relatedly, for the isomeric 1,4-hexadienes 14 and 15, equation 8 may be used. 

If various feeds give the same TPR spectrum for their end product, a common rate determining step can be assumed. This was the situation when TPR spectra of benzene formed over Pt-AljOj from adsorbed n-hexane, 1-hexene, and 1,5-hexadiene were studied. This re-confirms the hexane-hexene-hexadiene stepwise mechanism since cyclohexane, cyclohexene, and cyclohexadiene gave another type of TPR spectrum (62b). 

Wild and cultivated blackberries have been used as food and medicine for hundreds of years [106]. Approximately 150 volatiles have been reported from blackberries [107]. The aroma profile is complex, as no single volatile is described as characteristic for blackberry [108, 109]. Several compounds have been suggested as prominent volatiles in blackberries using AEDA, e.g. ethyl hexanoate, ethyl 2-methylbutanoate, ethyl 2-methylpropanoate, 2-heptanone, 2-undecanone, 2-heptanol, 2-methylbutanal, 3-methylbutanal, hexanal, ( )-2-hexenal, furaneol, thiophene, dimethyl sulfide, dimethyl disulfide, dimethyl trisulfide, 2-methylthiophene, methional, a-pinene, limonene, linalool, sabinene. 

The cloning, characterisation and expression of many lipoxygenase (TOX) [17] and hydroperoxide lyase (HPL) [18] genes has led researchers to propose new processes for the production of green note flavours. HPT specifically produces the highly demanded compound ds-3-hexenal from the 13-hydroperoxide of linolenic acid and hexanal from the hydroperoxide of linoleic acid, both of which are formed by TOXs (Scheme 26.2). 

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-... 

Clausen et al. (2005) found many similarities between odorants emitted from linseed oil as well as from a floor oil made of this linseed oil, concluding that the odorants of the linseed oil are also responsible for the odor of the floor oil. Of the 139 listed perceived odorants only 45 were identified by GC—MS library search and retention characteristics. Important odorants with a high detection frequency were acetaldehyde, propanal, butanal, pentanal, 2-pentenal, hexanal, 2-hexenal, heptanal, 2-heptenal, 2,4-heptadienal, octanal, 2-octenal, nonanal, 2-nonenal, 2-decenal, benzaldehyde, l-penten-3-one, l-penten-3-ol, pentyl oxiran, acetic acid, propionic acid, butanoic acid, pentanoic acid, hexanoic acid, octanoic acid. 

Pyrolysis of the high boiling products obtained from hexene afforded hexanal (Reaction 9a), 2-hexanone (Reaction 9b) and hexenyl acetates (Reaction 9c). 

As based on the pair of op>en-chain compounds cw-3-hexene/hexane From the A/fJ-value of 31.00 kcal mol given by Stull et al., 1969. Pedley and Rylance (1977) report a A// value of 37.45 kcal mol , from which the relative strain of cyclobutene is calculated as -1-2.6 kcal mol ... 

Figure 7, Scheme for VOC formation from leaf fatty acids following wounding. The enzymatic origins of hexanal and hexenal family VOCs are shown, and the unique or major positive ions detected by PTR-MS are indicated in parentheses for many of these VOCs. Abbreviations ADH, alcohol dehydrogenase AT, acetyl transferase IF, isomerization factor. Reprinted with permission of the American Geophysical Union from Ref. [66]. 

Addition of aliphatic hydrocarbons to ethylenic compounds occurs under the influence of catalysts such as sulfuric acid, phosphoric acid, and aluminum chloride.1 For instance, isobutane and propene afford the three isomeric heptanes. This reaction is not of particular importance in laboratory practice. However, addition of aromatic compounds to olefins is often a practicable method of alkylation.2 Thus ethylbenzene is formed from ethylene and benzene under the influence of aluminum chloride or when the hydrocarbon mixture is passed over a silica-alumina catalyst and Brochet3 obtained 2-phenyl-hexane from benzene and 1-hexene. The C-C bond is always formed to the doubly bonded carbon atom carrying the smaller number of hydrogen atoms benzene and propene, for instance, give cumene, which is important as intermediate in the preparation of phenol. Corson and Ipatieff4 report that benzene reacts especially readily with cyclohexene, yielding cyclohexylbenzene ... 

Guava flavor G.f., resembling pear and quince flavor, contains )8- caryophyllene, numerous fruit esters, e.g., ethyl butanoate and ethyl hexanoate, cinna-myl acetate (see cassia oil) and the green notes from hexanal, ( )-2- hexenal, and (Z)-3- hexen-l-ol. Important trace components are C -C,g-dienals, Fura-neol, some pyrazines and thiazoles, as well as 6-mercapto-I-hexanol(CiHnOS, Mr 134.24,CAS [1633-78-9]) ... 

Oxidized fish oils, rich in n-3 polyunsaturated fatty acids, produced volatile compounds more readily than oxidized vegetable oils, rich in linoleic acid. Activation energy for the formation of propanal from fish oils was lower than for the formation of hexanal from vegetable oils. A mixture of aldehydes contributed to the characteristic odors and flavors of oxidized fish, described as rancid, painty, fishy and cod liver oil-like (Table 11.21). Oxidation of unsaturated fatty acids in fish was related to the formation of 2-pentenal, 2-hexenal, 4-heptenal, 2,4-heptadienal and 2,4,7-decatrienal. The fishy or trainy characteristic of fish oil was attributed to 2,4,7-decatrienal. Studies of volatiles from boiled trout after storage showed significant increases in potent volatiles by aroma extraction dilution analysis (Table 11.22). Volatiles with the highest odor impact included l,5-octadien-3-one, 2,6-nonadienal, 3-hexenal, and 3,6-nonadienal. 3,6-Nonadienal and 3-hexenal were considered to contribute most to the fatty, fishy flavor in stored boiled fish. 

Leaf Wounding In this example, the emissions of VOCs from the hexanal and hexenal families... 

The current pool of y 3 data for ionic liquid-organic solute interactions exceeds those obtained by alternative techniques such as headspace chromatography, dilutor and the static technique. As mentioned previously, experimental investigations on ionic liquids from an industrial perspective have largely been guided by separation problems of interest to the chemical and petrochemical industries such as alkane-aromatic, cyclo-alkane-aromatic and alkane-alkene mixtures. In this regard, selectivities at infinite dilution (5j ) are presented in Table 3 for (i) n-hexane-benzene, (ii) cyclohexane-benzene and (iii) n-hexane-l-hexene separations in various ionic liquid and commercially significant solvents. 

Overall reaction of enzyme system consisting of lipoxygenase and hydroperoxide lyase in tea chloroplasts was investigated. As described earlier, tea chloroplast thylakoids contained lipoxygenase and hydroperoxide lyase. ( ) This enzyme system catalyzes formation of C -aldehydes including hexanal, (3Z)-hexenal and (2 )-hexenal from linoleic acid and linolenic acid but not C -aldehydes from these fatty acids. 

As expected from the structure, the products were hexanal from linoleic acid and (3Z)-hexenal and (2E)-hexenal from linolenic acid. Methyl llnoleate, llnoleyl alcohol and Y-llnolenlc acid did not act as the substrate although... 

What kinds of information can we get from a mass spectrum Certainly the most obvious information is the molecular weight, which in itself can be invaluable. For example, if we were given samples of hexane (MW = 86), 1-hexene (MW = 84), and 1-hexyne (MW = 82), mass spectrometry would easily distinguish them. 

From these data, some key information can be drawn in both cases, the couple methane/pentane as well as the couple ethane/butane have similar selectivities. This implies that each couple of products (ethane/butane and methane/pentane) is probably formed via a common intermediate, which is probably related to the hexyl surface intermediate D, which is formed as follows cyclohexane reacts first with the surface via C - H activation to produce a cyclohexyl intermediate A, which then undergoes a second C - H bond activation at the /-position to give the key 1,3-dimetallacyclopentane intermediate B. Concerted electron transfer (a 2+2 retrocychzation) leads to a non-cychc -alkenylidene metal surface complex, C, which under H2 can evolve towards a surface hexyl intermediate D. Then, the surface hexyl species D can lead to all the observed products via the following elementary steps (1) hydrogenolysis into hexane (2) /1-hydride elimination to form 1-hexene, followed by re-insertion to form various hexyl complexes (E and F) or (3) a second carbon-carbon bond cleavage, through a y-C - H bond activation to the metallacyclic intermediate G or H (Scheme 40). Under H2, intermediate G can lead either to pentane/methane or ethane/butane mixtures, while intermediate H would form ethane/butane or propane. 

Kanasawud and Crouzet have studied the mechanism for formation of volatile compounds by thermal degradation of p-carotene and lycopene in aqueous medium (Kanasawud and Crouzet 1990a,b). Such a model system is considered by the authors to be representative of the conditions found during the treatment of vegetable products. In the case of lycopene, two of the compounds identified, 2-methyl-2-hepten-6-one and citral, have already been found in the volatile fraction of tomato and tomato products. New compounds have been identified 5-hexen-2-one, hexane-2,5-dione, and 6-methyl-3,5-heptadien-2-one, possibly formed from transient pseudoionone and geranyl acetate. According to the kinetics of their formation, the authors concluded that most of these products are formed mainly from all-(E) -lycopene and not (Z)-isomers of lycopene, which are also found as minor products in the reaction mixture. 

Materials. 5-Methyl-1,4-hexadiene was obtained by the codimerization of isoprene and ethylene with a catalyst (18) consisting of iron octanoate, triethylaluminum and 2,2 -bi-pyridyl. The product mixture which contained principally 5-methyl-1,4-hexadiene and 4-methy1-1,4-hexadiene was fractionated through a Podbielniack column to yield high purity (>99%) 5-methylxhexadiene, b.p. 92.80C,njj 1.4250 (Lit. (19) b.p. 88-89°C, np 1.4249). 1-Hexene (99.9% purity), 1-decene (99.6% purity), 4-methyl-1-hexene (99.5% purity) and 5-methyl-l-hexene (99.7% purity) were obtained from Chemical Samples Co. 6-TiCl3 AA (Stauffer Chemical Co.j contains 0.33 mole AICI3 per mole of TiClj). Diethylaluminum Chloride was obtained from Texas Alkyls (1.5 M in hexane). 

The reduction of 2-methylthiophene, however, yielded only small amounts of dihydro-2-methylthiophene and a high yield of pcntcnethiol. It was apparent that substitution in the 2-position inhibited the production of the dihydrothiophene and favored more complete reduction. It was interesting to note that the reduction of 2,5-dimethylthiophene furnished small amounts of hexan-2-one. It was believed that the crude hexenethiol probably contained some hexene-2-thiol-2 which is capable of isomerization to hexane 2-thione from which the ketone can be formed by the action of alkali as follows ... 

These results indicate the formation of 1-hexene from -hexane in both helium and hydrogen. The absence of cyclohexane is due to the lack of its formation and not to its rapid further reaction to benzene. The rate of hexene aromatization is more rapid than that of hexane (52, 54). 

The radioactivity of hexene fraction was due to incomplete separation from n-hexane ( tailing ). 

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