2-Methyl-2-butene preparation

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]. 

As a method for the preparation of alkenes a weakness in the acid catalyzed dehydration of alcohols IS that the initially formed alkene (or mixture of alkenes) sometimes isomenzes under the conditions of its formation Write a stepwise mechanism showing how 2 methyl 1 butene might isomenze to 2 methyl 2 butene in the presence of sulfuric acid... 

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). 

The synthesis of isotactic polymers of higher a-olefins was discovered in 1955, simultaneously with the synthesis of isotactic PP (1,2) syndiotactic polymers of higher a-olefins were first prepared in 1990 (3,4). The first commercial production of isotactic poly(l-butene) [9003-29-6] (PB) and poly(4-methyl-l-pentene) [9016-80-2] (PMP) started in 1965 (5). 

Esters of / fZ-amyl alcohol can be obtained by acylation of 2-methyl-2-butene in the presence of trifluoromethanesulfonic acid (44). The esters produced, in high yields, from reaction of amyl alcohols with carboxyHc anhydrides, are used as intermediates for preparation of pyryflum salts (45,46) and alkaloids (47). Tria2oles prepared by acylation of 3-methyl-1-butanol are useful as herbicides (48). 

The regiochemistry is determined by the regiochemistry of the fluoride ion addition reaction, that is, via the most stable perfluorocarbanion intermediate Von Werner used a similar reaction to prepare silver compounds from perfluoro-2-methyl-2-butene and perfluoro 2 methyl-2-pentene [271] Silver(I) fluoride adds to bis(ttitluoromethyl)ketene in DMF without fluoride ion catalysis [270] The analogous trifluorovinylsulfurpentafluoride reacts similarly to give the isolable pentafluorosulfur derivative [272] (equation 187)... 

Due to the abundance of epoxides, they are ideal precursors for the preparation of P-amino alcohols. In one case, ring-opening of 2-methyl-oxirane (18) with methylamine resulted in l-methylamino-propan-2-ol (19), which was transformed to 1,2-dimethyl-aziridine (20) in 30-35% yield using the Wenker protocol. Interestingly, l-amino-3-buten-2-ol sulfate ester (23) was prepared from l-amino-3-buten-2-ol (22, a product of ammonia ring-opening of vinyl epoxide 21) and chlorosulfonic acid. Treatment of sulfate ester 23 with NaOH then led to aziridine 24. ... 

Tributyl(3-methyl-2-butenyl)tin was prepared according to the preceding procedure from 1-chloro-3-methyl-2-butene, tributyltin chloride, and magnesium. 

This is a general method for making N-alkylallenimines, and the following ones have been made in this way N-methyl-,6 N-propyl-,6 N-isopropyl-,4 N-butyl-,4 N-hexyl-,e and N-(3,5,5-tri-methylhexyl)-.4 N-Z-Butylallenimine6 and l-(l-allenimino)-2-hydroxy-3-butene 7 have also been prepared by this method, but with sodium amide/2-bromoallylamine mole ratios of 1.75 and 2.1, respectively. This method has been used for the preparation of pure N-alkylpropargylamines from 2-chloroallylaminesA7 The optimum sodium amide/2-chloroallylamine ratio for the preparation of N-alkylpropargylamines is 2.1. 

Hegedus synthesis of ( )-clavicipitic acid //-acetyl methyl ester culminated in the Pd-induced cyclization of 238 to 239, the latter of which was reduced to the target mixture [251], Substrate 238 was prepared via a Heck reaction with the corresponding 4-bromo compound 223 and 2-methyl-3-buten-2-ol (83%). The cyclization also occurs with tosic acid (97%). 

PREPARATION OF VINYL TRIFLUOROMETHANESUL-FONATES 3-METHYL-2-BUTEN-2-YL TRIFLATE... 

Melhyl-l-propanol Isobutyl Alcohol) and 2-Phenyl-1-propanol Herling and Pines (SO) studied the dehydration of 2-methyl-l-propanol and 2-phenyl-1-propanol. The two alcohols were passed over alumina under nonacidic conditions at temperatures of 350° and 270°, respectively (Tables III and IV). The 2-methyl-l-propanol underwent, in part, skeletal isomerization forming butenes, whereby the ratio of cisjtrans 2-butene produced was four to six times greater than the equilibrium ratio. The extent of skeletal isomerization depended to some extent on the method of preparation of the alumina. 

Pillai and Pines (84) found that neopentyl alcohol, mixed with 10% by weight of piperidine and passed over alumina prepared from aluminum isopropoxide, yielded 2-methyl-l-butene and 2-methyl-2-butene, in a maximum ratio of 3, and small amounts of 1,1-dimethylcyclo-propane. However, lert-pentyl alcohol yielded these two olefins in a maximum ratio of only 1.4, and none of the cyclopropane was produced (Table VI). Because of these facts a carbonium ion mechanism which is applicable to ferf-pentyl alcohol is not adequate to explain the rearrangement taking place during the dehydration of neopentyl alcohol,... 

A similar method can be used for the addition of carbon tetrachloride to nonpolymerizable olefins (e.g., 1-octene, 2-octene, 1-butene, 2-butene) pure adducts are obtained in yields of over 90% if the components are allowed to react at 100° for 6 hours. Adducts of carbon tetrachloride with vinylic monomers (styrene, butadiene, acrylonitrile, methyl acrylate, etc.) can be prepared in good yields by substituting cupric chloride dihydrate in acetonitrile for ferric chloride hexahydrate and benzoin. 

Butenes were subjected to photosensitized reaction with molecular oxygen in methanol. 1-Butene proved unreactive. A single hydroperoxide, l-butene-3-hydroperoxide, was produced from 2-butene and isolated by preparative gas chromatography, Thermal and catalyzed decomposition of pure hydroperoxide in benzene and other solvents did not result in formation of any acetaldehyde or propionaldehyde. The absence of these aldehydes suggests that they arise by an addition mechanism in the autoxidation of butenes where they are important products. l-Butene-3-hydroperoxide in the absence of catalyst is converted predominantly to methyl vinyl ketone and a smaller quantity of methyl vinyl carbinol —volatile products usually not detected in important quantities in the autoxidation of butene. 

The preparation of acyclic allylic hydroperoxides has been described before (3, 7, 9), but it is not clear how the reactivities differ from the better known saturated hydroperoxides and cyclic allylic hydroperoxides. Dykstra and Mosher prepared allyl hydroperoxide by the reaction of allyl methanesulfonate with hydrogen peroxide and alcpholic potassium hydroxide and purified the hydroperoxide by gas chromatography. It detonated on heating and decomposed on exposure to light but was relatively stable in the cold and dark. The isomeric allylic hydroperoxides formed from the autoxidation of the branched olefin, 4-methyl-2-pentene, have also been isolated and were not abnormally reactive (3). In the present study, cis- and trans-2-butene were photooxidized in the presence of methylene blue as a sensitizer (14), and the product, l-butene-3-hydro-peroxide, was isolated by preparative chromatography. 1-Butene proved unreactive and 2-butene-l-hydroperoxide could be formed only by isomerization of the secondary hydroperoxide. 

The conditions for the photocycloaddition (discussed in detail in a later section of this review) can be relatively mild. There is usually a small probability of the oxetane being destroyed in dark reactions which would probably preclude isolation after preparation by any method. One mode of decomposition of oxetanes is fragmentation, either back to the starting materials or to the other possible carbonyl compound and olefin. For example, the oxetane from 4,4 -dimethoxybenzophenone and isobutylene forms readily and is easily detected and characterized by infrared and NMR spectroscopy. All efforts to purify it, however, have led to its decomposition into formaldehyde and the diarylethy-lene.17 37 In some cases, as with fluorenone and isobutylene37 or 2-methyl-2-butene,25b the oxetane is apparently too unstable for detection, but the presence of the olefin 96 attests to its formation. 

C12H18O, Mr 178.28, does not occur in nature. It is a colorless liquid, >/ o.oi3kPa 86-91 °C, 20 0.960-0.964, Up 1.511-1.514, with a long lasting diffusive, fresh, floral, rose odor. The alcohol is prepared by hydrogenation of tetrahydro-4-methylene-5-phenylpyran which is obtained by cyclocondensation of benzaldehyde with 3-methyl-3-buten-l-ol in the presence of -toluenesulfonic acid [144]. 

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