Hexene, 2 -and

Dicobaltoctacarbonyl at concentrations about 10-3 M was an excellent catalyst (lib) for hydrosilation of 1-hexene by common silanes, including (MeO)3SiH, Et3SiH, and PhCl2SiH, to give exclusively n-hexyl silanes. The only observable side reaction was formation of hexene-2 and hexene-... 

In these isotactic polymers, the optical purity of the monomer affected the optical activity via the relationship to the excess helical sense of the polymer (Figure l).47 In the case of isotactic poly[(5)-4-methyl-1-hexene] (2) and poly[(A)-3,7-dimethyTl-octene] (3), an increase in the optical purity of the monomers resulted in an increase in the optical activity of the polymers in a nonlinear fashion the optical activity of the polymers leveled off when the optical purity of the monomer reached ca. 80%. In contrast, in the case of isotactic poly[(5)-5-methyl-l-heptene] (4), the... 

Hexene and catalyst (0.54 wt wt ratio) were placed in a sealed tube and heated for 1.75 hour at 64°. Analysis of the liquid product (mole %) gave 1-hexene (19.0%), Zraw5-hexene-2 and -3 (74.5%), hexene dimers (5.5%), and hexene trimers (1.0%). Evidence for extensive transfer of deuterium from catalyst OD groups to olefin as C—D bonds is given in Table XIII. 

Although anti-Markovnikov addition is favored for many olefins, significant amounts of branched nitrile products are often observed. This can be because of rapid olefin isomerization prior to hydrocyanation. For example, it is estimated that 85% of the 2-methylhexenenitrile formed in hexene-1 hydrocyanation results from direct hydrocyanation of hexene-2 and only 15% from Markovnikov addition to hexene-1 . 

In a similar manner the copol3onerizations of trans-butene-2 with hexene-2 and of butene-1 with hexene-1 were also carried out (30) and almost identical results (Tables 5 and 6 were obtained. 

Methyl Isoamyl Ketone. Methyl isoamyl ketone [110-12-3] (5-methyl-2-hexanone) is a colorless Hquid with a mild odor. It is produced by the condensation of acetone and isobutyraldehyde (164) in three steps which proceed via the keto-alcohol dehydration to 5-methyl-3-hexen-2-one, and hydrogenation to 5-methyl-2-hexanone. 

A careful study of the photoinitiated addition of HBr to 1-hexene established the following facts. (1) The quantum yield is 400, (2) The products are 1-bromohexane, 2-bromohexane, and 3-bromohexane. The amounts of 2- and 3-bromohexane formed are always nearly identical and increase from about 8% each at 4°C to about 22% at 63°C, (3) During the course of the reaction, small amounts of 2-hexene can be detected. Write a mechanism that could accommodate all these facts. 

It also explains the /Z selectivity of products at low conversions (kinetic ratio. Scheme 19). In the case of propene, a terminal olefin, E 2-butene is usually favoured (E/Z - 2.5 Scheme 19), while Z 3-heptene is transformed into 3-hexene and 4-octene with EjZ ratios of 0.75 and 0.6, respectively, which shows that in this case Z-olefins are favoured (Scheme 20). At full conversion, the thermodynamic equilibriums are reached to give the -olefins as the major isomers in both cases. For terminal olefins, the E olefin is the kinetic product because the favoured pathway involved intermediates in which the [ 1,2]-interactions are minimized, that is when both substituents (methyls) are least interacting. In the metathesis of Z-olefins, the metallacyclobutanes are trisubstituted, and Z-olefins are the kinetic products because they invoke reaction intermediates in which [1,2] and especially [1,3] interactions are minimized. 

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. 

A simple synthesis of allethrolone, the alcohol component of the allethrine (commercially important insecticide), is shown in Scheme 4.11. The conjugated addition of 3-phenylthio-5-hexene-2-one to 1-nitro-l-propene followed by the Nef reaction and aldol condensation gives allethrolone in good yield.68... 

As a check on our experimental and calculation procedures, we examined the copolymerization of 1-hexene and 1-decene (Table V) which had been investigated by Lipman (30). The copolymer composition was determined by using 300 MHz H-NMR and the reactivity ratios were calculated by the Tidwell-Mortimer method (22). The values of r (1-hexene) = 1.1 + 0.2 and r2 (1-decene) = 0,9 + 0,2 are in excellent agreement with Lipman s values of 1,3 and 0.9, respectively. It should be noted that in the latter investigation the copolymers were analyzed by IR spectroscopy and the reactivity ratios were calculated according to the method of Mayo and Lewis (32). 

Copolymer composition vs. monomer feed data were then obtained for 1-hexene (M ) and 5-methyl-1,4-hexadiene copolymerizations (Table VI). The data show that the copolymer compositions measured by 300 MHz %-NMR spectroscopy are essentially identical to the monomer feed. The calculated reactivity ratios were 1.1 + 0.2 for each of the two monomers. 

Mannig and Noth reported the first example of rhodium-catalyzed hydroboration to C=C bonds in 1985.4 Catecholborane reacts at room temperature with 5-hexene-2-one at the carbonyl double bond when the reaction was run in the presence of 5mol.% Wilkinson s catalyst [Rh(PPh3)3Cl], addition of the B—H bond across the C=C double bond was observed affording the anti-Markovnikoff ketone as the major product (Scheme 2). Other rhodium complexes showed good catalytic properties ([Rh(COD)Cl2]2, [ Rh(PPh3)2(C O )C 1], where... 

In contrast to the examples of selectivity control discussed in the previous sections, the problem here is control of the regioselectivity of the individual reaction steps. This is evident from the Scheme 5. In the first reaction step the nickel-hydride species adds to propene forming a propyl- or isopropyl-nickel intermediate this step is reversible, and the ratio of the two species can be controlled both thermodynamically and kinetically. In the second step, a second molecule of propene reacts to give four alkylnickel intermediates from which, after j8-H elimination, 8 primary products are produced (Scheme 5). 2-Hexene and 4-methyl-2-pentene could be the products of either isomerization or the primary reaction. Isomerization leads to 3-hexene, 2-methyl-2-pentene (the common isomerization product of 2-methyl-1-pentene and 4-methyl-2-pen-tene), and 2.3-dimethyl-2-butene. It can be seen from the Scheme 5 that, if the isomerization to 2-methyl-2-pentene can be neglected, the distribution of the products enables an estimate to be made of the direction of... 

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