1- Pen tene

Dimethy1-2-neopentylpen-tanal, by oxidation of 4,4-dimethy1-2-neopentyl-1-pen-tene with chromyl chloride, 51, 6... 

Clear, colorless, flammable liquid with a characteristic, sweetish odor similar to hexane or 1-pen-tene. An odor threshold concentration of 140 ppbv was reported by Nagata and Takeuchi (1990). 

None of the ruthenium complexes gave greater than trace amounts of disproportionation. Both of the nitrosyl-containing ruthenium derivatives showed some double-bond isomerization activity with 1-2% 1-pen-tene being observed. 

The scheme reduces to its most simple form when carbon monoxide is the only ligand present in the system, because equilibria of mixed ligand/carbon monoxide complexes do not occur. The kinetics of the hydroformylation reaction using hydrido rhodium carbonyl as the catalyst was studied by Marko [20]. For 1-pen-tene the rate expression found is ... 

The isomerized structure dominates even at - 100° C, but accounts for only 70% of the repeat units at - 130° C. Similar but more complicated structures are formed in 4-methyl-1-butene polymerizations by competing hydride and methide shifts [298]. Other monomers whose propagating carbenium ions isomerize include 5-methyl-l-hexene, 4,4-dimethyl-1-pen-tene and some terpenes [299]. 

Several years ago dimerization was essentially achieved (and is still currently performed) by means of acidic catalysts, sometimes as liquids but mainly as solids. However, in spite of its economic interest owing to its low price and low sensitivity to impurities, cationic oligomerization is limited in scope, the main drawbacks being its poor selectivity and low activity toward linear olefins. Organometallics of highly electropositive metals (aluminum, potassium) afford better selectivities but their specificity and their poor activity restrict their use to some specialized syntheses, e. g., dimerization of propene into 2-methyl-1-pen-tene (Al(/-Pr)3) or 4-methyl-1-pentene (K). Coordination catalysts offer a broader spectrum of activity (which is often the opposite of that observed in cationic reactions) and more diversified selectivities their practical use can be expected to grow. 

Propylene has been co-polymerized with a broad set of higher olefins to isotactic co-polymers, including 1-pen-tene, 4-methyl-1-pentene, 1-hexene, 1-heptene, 1-octene,... 

Figure 3. Diasterecmeric end groups result from the attack of the dia-stereotopic faces of 3-methyl-1-pen-tene. For the configurational notation see Ref. 18. Reproduced with permission of the authors from Ref. 18.

R = C6Hs 3-methoxymethoxy-5-n itro-4-phenyl-1 -pen tene yield 40% (antUsyn) 54-35... 

The prediction that tetracarbonylcobalt hydride would act as a catalyst in hydroformylation reactions 133, 224) has been amply verified for example, the stoichiometric hydroformylation, using HCo(CO)4, of 1-pen-tene at room temperature affords a variety of isomeric aldehydes 187). Also, HCo(CO)4 is formed under the high pressure (100 atm. 1 1 H2 CO) and temperature (100°-300°C) conditions of the hydroformylation reaction 183, 226). 

Pen- tene 2-Pen- tene 2Methyl- 1-butene 1-Hex- anol 2-Me- thyl- 1-pen- tanol 2-Ethyl- 1-buta- nol ... 

The kinetics for hydroboration of aikenes are conducted in various solvents such as carbon tetrachloride, hexane, cyclohexane, benzene, and THE 9-BBN exists predominantly as the dimer (9-BBN)2 [2]. After the addition of olefins, at 25 °C, the aliquots from the reaction mixture are removed after appropriate intervals of time, quenched with an excess methanol, and analyzed by GLC for residual olefin. All operations are performed under nitrogen until identical rates are observed for more reactive olefins such as 1-hexene, 2-methyl-1-pen-tene, 3,3-dimethyl-1-butene, and cyclopentene, and variation of olefin concentration does not alter the rate. These results establish that the reaction is first order (Eq. 4.1). Typical data for cyclopentene and cyclohexene are presented in Table 4.1 [1]. 

As discovered by Natta, Pino and coworkers(16,17), isotactic polymerization of chiral -olefins is stereoselective (e.g., isotactic poly-(R,S)-3-methyl-1-pen-tene consists of enantiomeric macromolecules which can be partially resolved.) If one considers that the isotactic steric control arises from the enantiose-lectivity of the chiral catalytic sites toward the enantiotopic carbon of the monomer(7,11) then stereoselectivity simply means that the insertion is dia-stereoselective. In other words, the diastereotopic faces of the monomer must have a different reactivity in the insertion (Figure 3) Figure 4 shows the - G NM spectrum of isotactic poly-(R,S)-3-methyl-l-pen-tene obtained in the presence of 6TiCl3-Al( - CH3)3 (sample 8). The resonances at 13.2Zj, 13A57i 15 09 and 15.2 ppm are due to the 0113 s of 2 - - C-2,3-di-methyl-pentyl end groups formed in the initiation step(l8). 

A square-planar nickel hydride complex is suggested as the catalytic species [589]. In the first step, the nickel hydride catalyst adds across the double bond of propylene to give two intermediates, namely, a propyl nickel and isopropyl nickel complex. Both of these intermediates can react further with propylene by insertion of the double bond into the nickel-carbon bond, resulting in formation of four more intermediates. ( -Elimination of nickel hydride from these intermediates produces the possible products of propylene dimerization, namely, 4-methyl-1-pen-tene, cis- and trans-4-methyl-2-pentene, 2,3-dimethyl-l-butene, n-hexene, 2-hexene, and 2-methyl-l-pentene. Terminal unbranched olefins are rapidly isomerized under the influence of catalyst by a process of repeated nickel hydride addition and elimination to the internal olefins. Therefore, under ordinary reaction conditions the yield of 4-methyl-l-pentene is low. 

As it is clear from Table 12.3, the incorporation of 1-butene and 1-pen-tene into the pol5 ropylene chain leads to a reduction in the elastic modulus and tensile yield stress, an increase in tensile strength parameters, and improvement of the elastic behavior of the copolymers. Figure 12.5 presents the stress-strain curves for propylene-1-butene and propylene-1-pentene copolymers. The incorporation of even small amounts of these comonomers into the chains of PP chains brings about appreciable modification. 

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