2- Methyl-2-butene reaction

Table I gives the compositions of alkylates produced with various acidic catalysts. The product distribution is similar for a variety of acidic catalysts, both solid and liquid, and over a wide range of process conditions. Typically, alkylate is a mixture of methyl-branched alkanes with a high content of isooctanes. Almost all the compounds have tertiary carbon atoms only very few have quaternary carbon atoms or are non-branched. Alkylate contains not only the primary products, trimethylpentanes, but also dimethylhexanes, sometimes methylheptanes, and a considerable amount of isopentane, isohexanes, isoheptanes and hydrocarbons with nine or more carbon atoms. The complexity of the product illustrates that no simple and straightforward single-step mechanism is operative rather, the reaction involves a set of parallel and consecutive reaction steps, with the importance of the individual steps differing markedly from one catalyst to another. To arrive at this complex product distribution from two simple molecules such as isobutane and butene, reaction steps such as isomerization, oligomerization, (3-scission, and hydride transfer have to be involved.

When -butenes are used, the initiation produces a secondary carbenium ion/butoxide. This species may isomerize via a methyl shift (Reaction (2)) or accept a hydride from isobutane to form the tertiary butyl cation (Reaction (3)). Isobutylene forms the tertiary cation directly. 

However, coUisional deactivation in solution is so effective that no vibration-ally excited species is present. The reaction of photochemicaUy generated methylene with 2-methylpropene-l-)- C yields, 2-methyl-butene, which is formed by allylic insertion. In the liquid phase 2 % of the rearranged product labeled in the 3-position are formed, whereas in the gas phase 8% of this olefin can be isolated. This can be interpreted as follows 4% of 2-methyl-butene in solution and 16% of 2-methyl-butene in the gas phase are formed by an abstraction-recombination mechanism involving triplet methylene 96). 

Doering and Prinzbach20 photolyzed CH2N2 in the presence of 2-methylpropene 1-14C in the liquid phase and in the gas phase at 400 mm. The product ratios (Table II) in the liquid were quite similar to the high pressure values of Frey and Knox et al., although Doering and Prinzbach also report no 3-methylbutene-l. The chief object of this work was to study the mechanism of the insertion reaction of methylene into CH bonds. The product 2-methyl-butene-l, which is formed entirely by insertion and not by isomerization, was separated from the reaction... 

The mechanism of Lewis acid-catalysed ene reactions was studied for reaction of 2-methyl-butene 44 with formaldehyde in the presence of diethylaluminium chloride in toluene 92... 

Ene-additions of alkenes and dienes to silene 6 are considerably slower than [2 + 4]-cycloadditions. cA-Substitution in the ene component of the reaction causes a small acceleration in rate relative to fraws-substitution, as illustrated in Table 2 by the relative rate constants for reaction of 6 with cis- and rraws-2-butene. Reaction with cis, trans-2,4-hexadiene produces only a single adduct (66 equation 51), corresponding to selective ene-reaction with the cA-methyl group in the diene. 

A C5 synthetic unit which has ylide functionality and which is likewise accessible from 2-hydroxy-2-methyl-but-3-enal-dimethylacetal (27) has proved suitable particularly for the synthesis of apocarotenals. The copper-catalyzed reaction of (27) with triphenylphosphine (15) in the presence of aqueous acid leads to 4-triphenyl-phosphonium-2-methyl-buten-2-al (33). The bifunctional C5 ylenal (34), which is important for carotenoid syntheses, is formed therefrom with proton acceptors. 

These findings are in agreement with Friedman and Morritz s (169) data which indicate that when benzene was alkylated with 3-methyl-butene-1 and A1C13 catalyst at 21° C. largely 2-phenyl-3-methylbutane formed (1,2 reaction) whereas at —40 °C. almost exclusively 2-phenyl-2-methylbutane was obtained (1,3 reaction). 

Kuraray An intermediate for 3-methyl 1,5-pentane diol Rh4(CO)12 with phosphorus ligand as the precatalyst hydroformylation of 2-methyl buten-4-ol followed by hydrogenation Reaction 5.10... 

The effect of electrical fields on the radiolysis of ethane has been examined by Ausloos et and this study has shown that excited molecules contribute a great deal to the products. The experiments were conducted in the presence of nitric oxide, and free-radical reactions were therefore suppressed. The importance of reactions (12)-(14) was clearly demonstrated by the use of various isotopic mixtures. Propane is formed exclusively by the insertion of CH2 into C2H6 and the yield is nearly equal to the yield of molecular methane from reaction (14). Acetylene is formed from a neutral excited ethane, probably via a hot ethylidene radical. Butene and a fraction of the propene arise from ion precursors while n-butane appears to be formed both by ionic reactions and by the combination of ethyl radicals. The decomposition of excited ethane to give methyl radicals, reaction (15), has been shown by Yang and Gant °° to be relatively unimportant. The importance of molecular hydrogen elimination has been shown in several studies ° °. ... 

The second stage in the process is required because the MTBE formation is an equilibrium reaction. The temperature needed ( 100°C) to achieve a sufficiently high rate of conversion means a decrease in isobutene equilibrium conversion (XiB = 0.9 at 65°C, Xjb = -0.75 at 100°C). The main side reaction in the MTBE process is the dimerization of isobutene towards di-isobutene (two isomers). Side reactions with essentially no significance are the formation of f-butyl alcohol (due to the presence of water as feed impurity), the formation of dimethyl ether from methyl alcohol, and the oligomerization of isobutene towards tri- and tetramers. A (three stage) process is also in operation which tolerates butadiene. The butadiene/ methyl alcohol reaction is faster than that of the n-butenes but consider-... 

The reaction of hydrogenation of the 3-methyl,butenal could be achieved in gaseous phase on well characterized surfaces of platinum exhibiting a relatively small number of active aloms(- ID15)-... 

METHYL-BUTEN-OL-(3) (115-18-4) Forms explosive mixture with air (flash point 56°F/13°C). Violent reaction with strong oxidizers. Reacts violently with aliphatic amines, alkalis, ammonium persulfate, boranes, bromine dioxide, isocyanates, nitric acid, perchlorates, permanganates, peroxides, sodium peroxide, sulfuric acid, uranium fluoride. 

Oxidative rearrangement takes place in the oxidation of the 1-vinyl-l-cyclo-butanol 31, yielding the cyclopentenone derivative 32[84], Ring contraction to cyclopropyl methyl ketone (34) is observed by the oxidation of 1-methylcyclo-butene (33)[85], and ring expansion to cyclopentanone takes place by the reaction of the methylenecyclobutane 35. [86,87]... 

Indene derivatives 264a and 264b are formed by the intramolecular reaction of 3-methyl-3-phenyl-l-butene (263a) and 3,3,3-triphenylpropylene (263b) [237]. Two phenyl groups are introduced into the /3-substituted -methylstyrene 265 to form the /3-substituted /3-diphenylmethylstyrene 267 via 266 in one step[238]. Allyl acetate reacts with benzene to give 3-phenylcinnamaldehyde (269) by acyl—O bond fission. The primary product 268 was obtained in a trace amount[239]. 

Like butadiene, allene undergoes dimerization and addition of nucleophiles to give 1-substituted 3-methyl-2-methylene-3-butenyl compounds. Dimerization-hydration of allene is catalyzed by Pd(0) in the presence of CO2 to give 3-methyl-2-methylene-3-buten-l-ol (1). An addition reaction with. MleOH proceeds without CO2 to give 2-methyl-4-methoxy-3-inethylene-1-butene (2)[1]. Similarly, piperidine reacts with allene to give the dimeric amine 3, and the reaction of malonate affords 4 in good yields. Pd(0) coordinated by maleic anhydride (MA) IS used as a catalyst[2]. 

Hydrometallation is catalyzed by Pd. Hydroboration of l-buten-2-methyl-3-yne (197) with catecholborane (198) gives the 1,4-adduct 199 with 84% selectivity. The ratio of Pd to phosphine (1 1.5) is important[l 10]. The vinyl sulfide 201 is prepared by a one-pot reaction of the thioalkyne 200 via a Pd-catalyzed hydroborution-coupling sequence using dppf as a ligand[l 11]. 

Our belief that carbocations are intermediates m the addition of hydrogen halides to alkenes is strengthened by the fact that rearrangements sometimes occur For example the reaction of hydrogen chloride with 3 methyl 1 butene is expected to produce 2 chloro 3 methylbutane Instead a mixture of 2 chloro 3 methylbutane and 2 chloro 2 methylbutane results... 

This oxidation process for olefins has been exploited commercially principally for the production of acetaldehyde, but the reaction can also be apphed to the production of acetone from propylene and methyl ethyl ketone [78-93-3] from butenes (87,88). Careflil control of the potential of the catalyst with the oxygen stream in the regenerator minimises the formation of chloroketones (94). Vinyl acetate can also be produced commercially by a variation of this reaction (96,97). 

Bromination in polar solvents usually gives /n j -3,4-dibromo-2-methyl-3-buten-2-ol in nonpolar solvents, with incandescent light, the cis isomer is the principal product (194). Chlorine adds readily up to the tetrachloro stage, but yields are low because of side reactions (195). 

Methyl /-Butyl Ether. MTBE is produced by reaction of isobutene and methanol on acid ion-exchange resins. The supply of isobutene, obtained from hydrocarbon cracking units or by dehydration of tert-huty alcohol, is limited relative to that of methanol. The cost to produce MTBE from by-product isobutene has been estimated to be between 0.13 to 0.16/L ( 0.50—0.60/gal) (90). Direct production of isobutene by dehydrogenation of isobutane or isomerization of mixed butenes are expensive processes that have seen less commercial use in the United States. 

Bromination of isoprene using Br2 at —5 ° C in chloroform yields only /n j -l,4-dibromo-2-methyl-2-butene (59). Dry hydrogen chloride reacts with one-third excess of isoprene at —15 ° C to form the 1,2-addition product, 2-chloro-2-methyl-3-butene (60). When an equimolar amount of HCl is used, the principal product is the 1,4-addition product, l-chloro-3-methyl-2-butene (61). The mechanism of addition is essentially all 1,2 with a subsequent isomerization step which is catalyzed by HCl and is responsible for the formation of the 1,4-product (60). The 3,4-product, 3-bromo-2-methyl-1-butene, is obtained by the reaction of isoprene with 50% HBr in the presence of cuprous bromide (59). Isoprene reacts with the reactive halogen of 3-chlorocyclopentene (62). 

MEK is a colorless, stable, flammable Hquid possessing the characteristic acetone-type odor of low molecular weight aUphatic ketones. MEK undergoes typical reactions of carbonyl groups with activated hydrogen atoms on adjacent carbon atoms, and condenses with a variety of reagents. Condensation of MEK with formaldehyde produces methylisopropenyl ketone (3-methyl-3-buten-2-one) ... 

Linear terminal olefins are the most reactive in conventional cobalt hydroformylation. Linear internal olefins react at less than one-third that rate. A single methyl branch at the olefinic carbon of a terminal olefin reduces its reaction rate by a factor of 10 (2). For rhodium hydroformylation, linear a-olefins are again the most reactive. For example, 1-butene is about 20—40 times as reactive as the 2-butenes (3) and about 100 times as reactive as isobutylene. 

Singlet oxygen reacts with olefins presumably by the "ene" reaction to form allyflc hydroperoxides (45,57), eg, l-methyl-2-propenyl hydroperoxide [20733-08-8] is produced from 2-butene (eq. 19). The regioselectivity of this reaction has been investigated (58). 

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