2- methyl-2-butene hydration

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]. 

Methyl Isopropyl Ketone. Methyl isopropyl ketone [563-80-4] (3-methyl-2-butanone) is a colorless Hquid with a characteristic odor of lower ketones. It can be produced by hydrating isoprene over an acidic catalyst at 200—300°C (150,151) or by acid-catalyzed condensation of methyl ethyl ketone and formaldehyde to 2-methyl-l-buten-3-one, foUowed by hydrogenation to the product (152). Other patented preparations are known (155,156). Methyl isopropyl ketone is used as an intermediate in the production of pharmaceuticals and fragrances (see Perfumes), and as a solvent (157). It is domestically available from Eastman (Longview, Texas) (47). 

Fig. 5.5.15 Spatially resolved 13C DEPT spectra recorded for the competitive etherification and hydration reactions of 2-methyl-2-butene (2M2B) to 2-methoxy-2-methylbutane (tert-amyl methyl ether, TAME) and 2-methyl-butan-2-ol (tert-amyl alcohol, TAOH), respectively. The molar composition of the feed was in the ratio 2 10 1 for 2M2B methanol water. The...

Olefins can be hydrated quickly under mild conditions in high yields without rearrangement products by the use of oxymercuration144 (addition of oxygen and mercury) followed by in situ treatment with sodium borohydride145 (2-24). For example, 2-methyl-1-butene treated with mercuric acetate,146 followed by NaBH4, gave 2-methy 1-2-butanol ... 

The best-known gas hydrates are those of ethane, ethylene, propane, and isobulaue. Others include methane and I butene, most of the fluorocarbon refrigerant gases, nitrous oxide, acetylene, vinyl chloride, carbon dioxide, methyl and ethyl chloride, methyl and ethyl bromide, cyclopropane, hydrogen sulfide, methyl mercaptan, and sulfur dioxide. 

Methyl ethyl ketone (MEK boiling point 769.6°C, density 0.8062, flash point -6°C) is an important coating solvent for many polymers and is made by the sulfation and hydration of 1 or 2-butene to sec-butyl alcohol, which is then dehydrogenated to the ketone (Fig. 1). 

Acid-catalyzed hydration of alkenes (Section 6.10) The elements of water add to the double bond In accordance with Markovnikov s rule. R2C = CR2 + H2O R2CHCR2 OH Alkene Water Alcohol CH3 (CH3)2C=CHCH3 CH3CCH2CH3 M2SU4 OH 2-Methyl-2-butene 2-Methyl-2-butanol (90%)... 

Table 10.9 lists the main economic data available on the production of methyl ethyl ketone from n-butenes, in two steps involving the intermediate formation of secondary butyl alcohol by sulfuric hydration followed by dehydrogenation, or directly by the Wacker/Hoechst technology. 

Step 1 of the hydration mechanism is similar to the first step in the addition of HBr. The proton adds to the less substituted end of the double bond to form the more substituted carbocation. Water attacks the carbocation to give (after loss of a proton) the alcohol with the —OH group on the more substituted carbon. Like the addition of hydrogen halides, hydration is regioselective It follows Markovnikov s rule, giving a product in which the new hydrogen has added to the less substituted end of the double bond. Consider the hydration of 2-methyl-2-butene ... 

Vertenol. See 3-Methyl-2-buten-1-ol Vertenol acetate. See Prenyl acetate Vertenol caproate. See Prenyl caproate Vertenol heptanoate. See Prenyl heptanoate Vertenol isobutyrate. See Prenyl isobutyrate Vertical Hydrated Lime MV-200. See Calcium hydroxide... 

Acid-catalyzed hydration reactions occur with Markovnikov orientation. For example, hydration of 2-methyl-2-butene gives 2-methyl-2-butanol, consistent with the intermediacy of the 3° 2-methyl-2-butyl carbocation. Moreover, hydration of 2-methyl-l-butene was also found to produce 2-methyl-2-butanol, and there was no indication of isomerization to 2-methyl-2-butene during hydration. These results suggest, but do not confirm, that the cationic intermediate undergoes nucleophilic attack by water faster than it loses a proton to revert to starting material. ... 

Steric effects may play a role in the regiochemistry of the reaction as well. While the oxymercuration-demercuration reaction is generally considered to give only Markovnikov hydration, as shown by predominant formation of 43, this regioselectivity is not absolute. For example, methoxymercuration of 3,3-dimethyl-l-butene produced 2% of 3,3-dimethylbutyl methyl ether (44, equation 9.42). ... 

Alkenes lacking phenyl substituents appear to react by a similar mechanism. Both the observation of general acid catalysis and a solvent isotope effect are consistent with rate-limiting protonation with simple alkenes such as 2-methyl-propene and 2,3-dimethyl-2-butene. The observation of general acid catalysis rules out an alternative mechanism for alkene hydration, namely, water attack on an alkene-proton complex. The preequilibrium for formation of such a complex would be governed by the acidity of the solution, and so this mechanism would exhibit specific acid catalysis. 

---