1-Hexene reactions chemistry

This chemistry is sometimes accomplished simultaneously in one reactor and sometimes in two separate reactors. In the former, the triethyl aluminum catalyst is lost in the latter, it is recycled. Sometimes the displacement compound is butene-1 or hexene-1, depending on the chain length of the final alpha olefin desired and the change in operating conditions necessary to effect the displacement reaction. 

The nitrosochlorination of olefins has been known for nearly a century and has materially contributed to the early development of the chemistry of ter-penes [68]. Studies of the scope of the reaction were not undertaken until relatively recently and results appear to be somewhat fragmentary. While 1-olefins such as 1-hexene, 1-heptene, and 1-octene do not react with nitrosyl chloride, the corresponding 2-isomers add the reagent in conformity with Markovnikov s rule as if NO+ and Cl- moieties were involved [69]. 

The transformation of 6-bromo-l-hexene (38) into methylcyclopentane by the action of tributyltin hydride (Scheme 7) typifies the richness of the C—C bond forming chemistry in question. A knowledge of the critical rate constants (kc, ku and Br in Scheme 7) allow, through control of substrate concentration, necessary selectivity criteria to be met. Specifically the 5-hexenyl radical (39) must undergo intramolecular addition to form the cyclopentylmethyl radical (40), 40 must abstract a hydrogen atom from tributyltin hydride and the tributylstannyl radical must abstract the halogen in 38 to form 39. These processes must proceed faster than any competing side reaction. 

Dienes, as the simplest polyene systems, are widely encountered in sex pheromones like (4E, 7Z)-4,7-tridecadienyl acetate (100), a component of the sex pheromone of the potato tuberworm moth (Phthorimaea operculella). This compund was synthesized by Kim and Park [54] starting from a protected 5-hexen-l-ol and utilizing the chemistry of thio-substituted phosphonates (Scheme 28). Thus, the Pummerer rearrangement of a-phosphoryl sulfoxide 101 with 5-hexenyl acetate 102 afforded 7-acetoxy-l-methylthiohept-3-enyl phos-phonate 103 as an E/Z=85 15 mixture, being unreactive in the Horner-Wittig reaction, even after OAc deprotection/THP reprotection. However, the reaction of the more reactive a-phosphoryl sulfone 104 with w-hexanal successfully led to the required 1,4-diene 105, as an ElZ = 70 30 mixture, in 86 % yield. The final pheromone 100 was obtained after the desulfonylation of 105 with sodium hydrosulfite and the OTHP OH OAc deprotection/reprotection procedures. 

The scope of this chemistry has recently been extended to terminal alkene substrates [68]. For example, 1-hexene was transformed to 88 in 68% yield under solvent-free conditions using Pd(PPh3)4 as catalyst (Eq. (1.39)). Asymmetric induction has also been achieved in these reactions, and ees of up to 94% have been obtained with a catalyst supported by a chiral phosphoramidite ligand [68c]. The mechanism of the terminal alkene diamination reactions has not yet been fiiDy elucidated, but it appears likely that allyUc C H activation/amination is involved. 

The term of alkene (olefin) metathesis was introduced by Calderon and coworkers in 1967 [13] to describe a reaction in which 2-pentene is converted to 2-butene and 3-hexene in the presence of tungsten hexachloride, ethanol, and ethyl aluminum dichloride (Scheme 6.1). Nowadays, this term covers all reactions associated with the exchange of carbene (alkylidene) groups between alkenes, and the reaction has become a key process in polymer chemistry, as well as in fine and basic chemical synthesis, including petrochemistry [14, 15]. Alkene metathesis only takes place in the presence of an appropriate catalyst, and considerable research efforts have been devoted to design more active, selective, and stable catalysts [16-24]. In this field, computational chemistry has contributed considerably by bringing information that could not be derived from experimental studies. 

Copolymers of ethylene with a-olefins also known as LLDPE are an important topic due to their enhanced mechanical properties, structural simplicity, and industrial importance. Copolymers of ethylene with 1 -butene, 1-hexene, and 1-octene, have been obtained by copolymerization via Ziegler-Natta and metallocene chemistry.While many studies deal with modification of the catalyst and optimization of the reaction s conditions, thermal behavior of LLDPE is more important for understanding the morphology of these materials.Inspired by the success obtained modeling EP copolymers via ADMET polymerization, extension of this investigation led us to the synthesis of PE with only ethyl branches precisely placed along the main backbone, or precisely sequenced... 

Chan, F., G.A. Reineccins, Reaction kinetics for the formation of isovaleraldehyde, 2-acetyl-1-pyrroline, di(H)di(OH)-6-methylpyranone, phenylacetaldehyde, 5-methyl-2-phenyl-2-hexenal, and 2-acetylfuran in model systems, in Maillard Reactions in Chemistry, Food, and Health, T.P. Labuza, G.A. Reineccius, V. Monnier, J.O. O Brien, J.W. Baines, Eds., Royal Chem. Soc. London, London, 1994, p. 131. 

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