Of 2,4,4-trimethyl-l-pentene

The two dimers of (CH3)2C=CH2 are formed by the mechanism shown in Figure 6.16. In step 1 protonation of the double bond generates a small amount of tert-butyl cation in equilibrium with the alkene. The car bocation is an electrophile and attacks a second molecule of 2-methylpropene in step 2, forming a new carbon-carbon bond and generating a carbocation. This new carbocation loses a proton in step 3 to form a mixture of 2,4,4-trimethyl-l-pentene and 2,4,4-trimethyl-2-pentene. 

Therefore, the base-catalyzed reaction of isobutylene yields the same dimer as the acid-catalyzed reaction although the mechanisms are completely different. Since olefin isomerizations are also catalyzed under these conditions, an equilibrium distribution of products is expected for example, the reaction of isobutylene yields 78% of 2,4,4-trimethyl-l-pentene and 22% of 2.4,4-trimethyl-2-pentene. 

The present inv tigation commenced by a r amination of the heme proposed by Kennedy and Gillham (9). Thus, t-BuCl initiator was added to a quiescent mixture of 2,4,4,-trimethyl-l-pentene and MejAl in methyl chloride at —78° C. The products were quantitatively separated and identified. In contrast to Kennedy and Gillham, who reported high conversions ( 90%), only very low ( 0.1 %) conversions were obtained in spite of repeated attempts in this work. Indeed, conversions remained low ( 1.0%) even after quadrupling the t-BuQ... 

Oxidation of terminal olefins to aldehydes. In a detailed procedure1 a mixture of 1.0 mole of 2,4,4-trimethyl-l-pentene (Eastman or MCB) and 11. of methylene chloride is stirred mechanically in a 5-1. three-necked flask fitted with a thermometer and a... 

Selectivity to ETBE is usually very high and the main side reactions are isobutene dimerization with formation of 2,4,4-trimethyl-l-pentene and 2,4,4-trimethyl-2-pentene (DIB), ethanol self-condensation to diethyl ether (DEE), water addition to isobutene with formation of tert-butyl alcohol (TBA) and the etherification of linear butenes, if present, to produce ethyl sec-butyl ether (ESBE). 

Figure 2 shows overall conversions of 2,4,4-trimethyl-l-pentene as a function of temperature obtained with Me3Al, Et3Al, Et2AlCl and Me2AlCl coinitiators in conjunction with f-BuCl initiator in methyl chloride. Clearly, the activity of the alkylaluminums is greatly affected by temperature, however, the effect is different for each system. 

The decomposition of highly branched octenes (Greensfelder and Voge, 13) occurs even more readily than that of the normal octenes. Thus, a mixture of 2,4,4-trimethyl-l-pentene and 2,4,4-trimethyl-2-pentene gave 63 per cent gas, the major constituent being isobutylene. Triisobutylenes are even more susceptible to catalytic cracking and extensive decomposition takes place at 360°C. at a space velocity of 2.9. 

The heats of hydrogenation of 2,4,4-trimethyl-l-pentene and of 2,4,4-trimethyl-2-pentene are -25.5kcal/mol and -26.8 kcal/mol, respectively. Which isomer is more stable Is the result consistent with the common generalization that the more stable alkene isomer is the one with the greater number of alkyl substituents on the carbon-carbon double bond If not, explain why the generalization does not offer the correct prediction in the case of these two compounds. 

Dehydrobromination of 2-bromo-2,4,4-trimethylpentane (78) with 4.0M KOH in ethanol at 70°C produces 86% of 2,4,4-trimethyl-l-pentene (79) cind 14% of 2,4,4-trimethyl-2-pentene (80). The heat of hydrogenation of 79 is —25.52 kcal/mol, while that of 80 is —26.79 kcal/mol. Is this dehydrobromination an example of Saytzeff orientation or Hofmann orientation ... 

To produce p-tert-octylphenol, phenol and diisobutylene (a mixture of 2,4,4-trimethyl-l-pentene and 2,4,4-trimethyl-2-pentene) are fed through a bed of ion-exchange resin in the ratio 1.5 1 the resin is maintained at a temperature of 100 to 105 °C by internal cooling tubes. The alkylation is restricted to 95% diisobutylene conversion, to avoid the formation of undesirable by-products. The reaction mixture, which is separated into its constituents by vacuum distillation, consists of 93 to 96% p-tert-octylphenol the concentration of o-tert-octylphenol is between 2 and 3%. 

Diisobutylene obtained from the C4 hydrocarbon family is a mixture of 2,4,4-trimethyl-l-pentene and 2,4,4-trimethyl-2-pentene. There is currently only one U.S. producer, two producers in the far east, and two Europe an manufacturers. The cost of diisobutylene is 50-75% higher than the more simply obtained trimer (nonene) or tetramer (dodecene). 

Problem 6.8. As shown in Scheme 6.33, the dimerization of 2-methylpropene [i50-butylene (CH3)2C=CH2] results in the formation of 2,4,4-trimethyl-l-pentene [(CH3)3CCH2C(CH3)=CH2] and 2,4,4-trimethyl-2-pentene [(CH3)3CH=C(CH3)2]. These isomers can be separated by gas chromatography. The separated isomers were examined by NMR spectroscopy, which quickly showed which was which. Sketch the spectra that were obtained. 

However, the extent of facilitation and the magnitude of the flux value are not constant for each alkene permeate. The facilitation factors are similar for both 1-hexene and 2-ethyl-l-butene signifying that the complexation reaction for these two molecules are very similar. The transport of 2,4,4-trimethyl-l-pentene exhibits both a lower flux and lower facilitation factor tiian for 1-hexene or 2-ethyl-l-butene. The reduced flux can be explained by the inaease in molecular size causing lower physical solubility and slower diffusion in the hydrated membrane. These effects are also reflected in the fluxes through Na+-form membranes. Alkane flux is dependent only upon solubility and diffusion in each membrane form. Similar alkane fluxes are observed for the Ag+- and Na+-exchanged membranes. 

Hydroformylation of 2,4,4-trimethyl-l-pentene, catalyzed by the high-nuclearity carbonyl cluster [Rhi2(CO)3o] at higher temperatures and pressures, also proceeded via cluster fragmentation driven by CO pressure, as shown by IR spectroscopy. 

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