Alkenes with sulfuric acid

Several j3-sultones are claimed to be formed by treatment of alkenes with sulfuric acid or by heating alkenesulfonic acids. Treatment of 2,2-dimethyl-1,1-diphenyl-1-propanol with concentrated sulfuric acid at room temperature is said to give 3-(l,l-diphenylethyl)-3-methyl-l,2-oxathietane 2,2-dioxide (96% yield). Treatment of sodium 3-bromo-2-hydroxybutanesulfonate with phosphorus trichloride is reported to give a low yield of 4-(l-bromoethyl)-l,2-oxathietane 2,2-dioxide.1,2-Oxathietane 2,2-dioxide is suggested as an intermediate in the reaction of /3-hydroxyethanesulfonyl chloride with trimethylamine to give the zwitterion 502. The first four-membered monocycUc sulfurane oxides 502a have been reported. 

Alkenes react with sulfuric acid to form alkyl hydrogen sulfates A proton and a hydrogen sulfate ion add to the double bond in accordance with Markovnikov s rule Alkenes that yield tertiary carboca tions on protonation tend to polymerize in concentrated sulfuric acid (Section 6 21)... 

When applied to the synthesis of ethers the reaction is effective only with primary alcohols Elimination to form alkenes predominates with secondary and tertiary alcohols Diethyl ether is prepared on an industrial scale by heating ethanol with sulfuric acid at 140°C At higher temperatures elimination predominates and ethylene is the major product A mechanism for the formation of diethyl ether is outlined m Figure 15 3 The individual steps of this mechanism are analogous to those seen earlier Nucleophilic attack on a protonated alcohol was encountered m the reaction of primary alcohols with hydrogen halides (Section 4 12) and the nucleophilic properties of alcohols were dis cussed m the context of solvolysis reactions (Section 8 7) Both the first and the last steps are proton transfer reactions between oxygens... 

Acids other than hydrogen halides also add to the carbon-carbon bond of alkenes. Concentrated sulfuric acid, for exanple, reacts with certain alkenes to form alkyl hydrogen sulfates. 

On the basis of the mechanism of cationic polymerization, predict the alkenes of molecular formula C12H24 that can most reasonably be formed when 2-methylpropene [(CH3)2C=CH2] is treated with sulfuric acid. 

The hydration of propylene with sulfuric acid catalyst in high-temperature water was investigated using a flow reaction system.31 The major product is isopropanol. A biopolymer-metal complex, wool-supported palladium-iron complex (wool-Pd-Fe), has been found to be a highly active catalyst for the hydration of some alkenes to the corresponding alcohols. The yield is greatly affected by the Pd/Fe molar ratio in the wool-Pd-Fe complex catalyst and the catalyst can be reused several times without remarkable change in the catalytic activity.32... 

By proper choice of catalyst and conditions, all alkenes can be made to undergo what may be termed conjunct polymerization (Ipatieff and Pines, 70), that is, polymerization accompanied by the formation of saturated hydrocarbons. Indeed, with some catalysts, for example with aluminum chloride, true polymerization of the olefin takes place only under special conditions. With sulfuric acid, the type of polymerization depends on the concentration of the acid conjunct polymerization... 

Detergents have been manufactured from long-chain alkenes and sulfuric acid, especially those obtained from shale oil or cracking of petroleum wax. These are sulfated with 90—98 wt % acid at 10—15°C for a 5-min contact time and at an acid—alkene molar ratio of 2 1 (82). Dialkyl sulfate initially forms when 96 wt % acid is added to 1-dodecene at 0°C, but it is subsequently converted to the hydrogen sulfate in 80% yield upon the further addition of sulfuric acid. The yield can be increased to 90% by using 98 wt % sulfuric acid and pentane as the solvent at -15°C (83). 

Azoles containing an acidic NH-group, e.g. 3,5-dimethylpyrazole, react with various alcohols in the presence of a catalytic amount of ruthenium-, rhodium-, and iridium-trialkylphosphite complexes to afford the corresponding A-alkyl derivatives with excellent yields (92CL575). Regioselective A-alkylation was achieved using alkenes and sulfuric acid (89JHC3). 

Sulfuric acid (or phosphoric acid) is preferred as an acid catalyst for addition of water to alkenes because the conjugate base, HSO40 (or H2P04e), is a poor nucleophile and does not interfere in the reaction. However, if the water concentration is kept low by using concentrated acid, addition occurs to give sulfate (or phosphate) esters. The esters formed with sulfuric acid are either alkyl acid sulfates R—0S03H or dialkyl sulfates (R0)2S02. In fact, this is one of the major routes used in the commercial production of ethanol and... 

Finch and Symons,87 on reinvestigation of the absorption of aliphatic alcohols and alkenes in sulfuric acid solution, showed that the condensation products formed with acetic acid (used as solvent for the precursor alcohols and alkenes) were responsible for the spectra and not the simple alkyl cations. Moreover, protonated mesityl oxide was identified as the absorbing species in the system of isobutylene, acetic acid, and sulfuric acid. 

Recall that alkyl substituents on the double bond increase the reactivity of alkenes toward electrophilic addition. Propene therefore reacts faster than ethylene with sulfuric acid, and the mixture of alkyl hydrogen sulfates is mainly isopropyl hydrogen sulfate, and the alcohol obtained on hydrolysis is isopropyl alcohol. 

Formation of iVz-alkyl derivatives as the only products from the reaction of N-unsubstituted tetrazoles with secondary and tertiary alcohols or the corresponding alkenes in sulfuric acid has been reported (Scheme 27) <2000H(53)1421>. 

A number of nitriles added to bicyclic alkenes after conversion into a nitrilium ion intermediate, generated by treatment with sulfuric acid. Thus, derivatives of 3-azatricyclo[5.3.1.04,9]undecene 30 were obtained starting from 2,6-dimethylenebicyclo[3.3.1]nonane 29 with total diastereose-lectivity187. 

The fact that alkenes dissolve in cold, concentrated sulfuric acid to form the alkyl hydrogen sulfates is made use of in the purification of certain other kinds of compounds. Alkanes or alkyl halides, for example, which are insoluble in sulfuric acid, can be freed from alkene impurities by washing with sulfuric acid. A gaseous alkane is bubbled through several bottles of sulfuric acid, and a liquid alkane is shaken with sulfuric acid in a separatory funnel. 

These ethers are prepared by reactions of the corresponding alcohols with sulfuric acid. Since a molecule of water is lost for every pair of alcohol molecules, the reaction is a kind of dehydration. Dehydration to ethers rather than to alkenes... 

In the case of base-induced elimination, the Peterson alkenation relies on the strong bond formed between silicon and oxygen, and the ready propensity for silicon to be attacked by alkoxide, to drive the reaction. In the original study by Peterson, the -silylcarbinols were prepared by the addition of (trimethylsilyl)methylmagnesium chloride to the carbonyl. The caibinols were subsequently eliminated by treatment with sodium or potassium hydride or with sulfuric acid to form the methylene derivatives in excellent yield. The Peterson reaction has proven to be of general utility in the synthesis of alkenes. ... 

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