4-Methylhexan-2-one

Plot a graph of logi0f against the molecular weight or alternatively the carbon number (i.e. the number of carbon atoms in the molecule) of the ketone. Estimate the retention time of a ketone containing six carbon atoms and check your result by a suitable injection. Finally examine the chromatographic behaviour of 3-methylbutan-2-one, 4-methylpentan-2-one and 5-methylhexan-2-one. 

Cullis and co-workers [80,85,86] have shown that group shifts involving ethyl radicals may also take place. Thus the presence of small yields (ca. 2 %) of 4-methylhexan-3-one and heptan-3-one in the products of the cool-flame oxidation of 3-ethylpentane show that the 3-ethyl-3-... 

A laser flash study of the photoreactions of hexan-2-one and 5-methylhexan-2-one has provided evidence for the existence of the triplet 1,4-biradicals produced by the y-hydrogen abstraction typical of Norrish Type II reactivity. The photochemical behaviour of the alkanone, nonan-5-one, in urea inclusion compounds has been studied. In solution, irradiation of nonan-5-one yields hexan-2-one, propylene, and two cyclobutanols. In the clathrate, the fragmentation products were essentially the same but only one cyclobutanol was observed. The cyclization fragmentation ratio was established as 0.67, compared with 0.32 in methanol. The authors suggest that the CIS-cyclobutanol has less stringent rotational requirements and that it is this isomer (43) which is formed in the clathrate. 

Beilstein Handbook Reference) BRN 0506163 EINECS 203-737-8 2-Hexanone, 5-methyl- HSDB 2885 Isoamyl methyl ketone Isopentyl methyl ketone Ketone, methyl isoamyl 2-Methyl-5-hexanone 5-Methyl-2-hexanone 5-Methylhexan-2-one Methyl isoamyl ketone Methyl isopentyl ketone MIAK UN2302. Liquid bp = 144 d = 0.888 hn = 176.188,192,196 nm (gas) slightly soluble in H2O. soluble in CCI4, very soluble in MezCO, CeHe, freely soluble in EtOH, Et20. 

In addition to the already mentioned acyloins, food products contain numerous other odorous a-hydroxyketones. For example, 3-hydroxypentan-2-one has ben identified in cheeses, durian, wines, sherry, asparagus, honey, tea, butter and soy sauce, 2-hydroxypentan-3-one in cheeses, durian, coffee, wine, sherry honey, butter and soy sauce, 2-hydroxyhexan-3-one in wine, 4-hydroxyhexan-3-one in durian and tea, 3-hydroxy-5-methylhexan-2-one in cheeses, 3-hydroxyoctan-2-one in beef and heated mutton fat, 5-hydroxyoctan-4-one in cocoa and 3-hydroxy-4-phenylbutan-2-one in wine, sherry and honey. 

Dimethylpentan-3-one Heptan-2-one Heptan-3-one Heptan-4-one 5-Methylhexan-2-one Butyl propanoate... 

What about the configuration at C2, the newly formed chirality center As illustrated in Figure 9.19, the stereochemistry at C2 is established by attack of Br ion on a carbocation intermediate in the usual manner. But this carbocation does not have a plane of symmetry it is chiral because of the chirality center at C4. Since the carbocation has no plane of symmetry, it is not attacked equally well from top and bottom faces. One of the two faces is likely, for steric reasons, to be a bit more accessible than the other face, leading to a mixture of R and S products in some ratio other than 50 50, Thus, two diastereomeric products, (2/ ,4fi)-2-bromo-4-methylhexane and (2S,4/i)-2-bromo-4-methylhexane, are formed in unequal amounts, and the mixture is optically active. 

The results of pyrolysis of polypropylene in air depends on the pyrolysis heating rate because the pyrolysis process competes with the oxidation [108], By heating between 120° C and 280° C in air, polypropylene is reported to generate ethene, ethane, propene, propane, isobutene, butane, isobutane, pentadiene, 2-methyl-1-pentene, 2,4-dimethyl-1-pentene, 5-methyl-1-heptene, dimethylbenzene, methanol, ethanol, 2-methyl-2-propene-1-ol, 2-methylfuran, 2,5-dimethylfuran, formaldehyde, acetaldehyde, acrolein, propanal, methacrolein, 2-methylpropanal, butanal, 2-vinylcrotonaldehyde, 3-methylpentanal, 3-methylhexanal, octanal, nonanal, decanal, ethenone, acetone, 3-buten-2-one, 2-butanone, 1-hydroxy-2-propanone, 1-cyclopropylethanone, 3-methyl-2-buten-2-one, 3-penten-2-one, 2-pentanone, 2,3-butanedione [109]. 

One can notice that the easiest route on all catalysts is the isomerization of 2-methylbutane-2- C to 2-methylbutane-3- C, involving certainly a symmetrical intermediate. This result, and the earlier mentioned one, fast isomerization of 3-methylhexane-3- C to 3-methylhexanes-2- C and -4- C (see Section III, p. 27), support the view that, irrespective of the exact nature of the mechanism, bond shift reactions involving symmetrical intermediates are favored over the other reaction pathways. 

Oxidation, When diphenylcyclopropenone is oxidised by m-chloroper-benzoic acid a mixture of benzil, diphenylacetylene and benzophenone (50 40 10) is formed [114]. Di-t-butylcyclopropenone provides only a trace of alkyne and the main product is 4,5-eDoxy-2,2,4,5-tetra-methylhexan-3-one, which is thought to arise by further oxidation of alkyne [114]. Alkaline hydrogen peroxide oxidises diphenylcyclopropenone to the same products, plus benzylphenyl ketone [114]. 

The x(HD) for the two nonane isomers are obtained by summing bond contributions and are listed in the last row of Table 9.2. As one can see, the x(HD) are very similar, differing by less then 1%, which suggess that the x(HD) index may be a suitable measure of molecular similarity. Based on the x(HD) index, the two most similar pairs among the 11 pairs of nonane isomers are 3,4-dimethylheptane and 3-ethyl-2-methylhexane. This can be seen from the last column in Table 9.3, in which... 

The phenomenon of handedness, or chirality, actually surfaces long before we encounter a molecule as complicated as rflwr-l,2-dimethylcyclopropane. We went right past it when we wrote out the heptane isomers in Figure 2.45 (p. 82). One of these heptanes, 3-methylhexane, exists in two forms. To see this, draw out the molecule in tetrahedral form using C(3) as the center of the tetrahedron (Fig. 4.2a). 

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