Acidity of alkenes

Step 3 IS new to us It is an acid-base reachon m which the carbocation acts as a Br0n sted acid transferrmg a proton to a Brpnsted base (water) This is the property of carbo cations that is of the most significance to elimination reactions Carbocations are strong acids they are the conjugate acids of alkenes and readily lose a proton to form alkenes Even weak bases such as water are sufficiently basic to abstract a proton from a carbocation... 

We can gam a general understanding of the mechanism of hydrogen halide addi tion to alkenes by extending some of the principles of reaction mechanisms introduced earlier In Section 5 12 we pointed out that carbocations are the conjugate acids of alkenes Therefore strong acids such as HCI HBr and HI can protonate the double bond of an alkene to form a carbocation... 

Little quantitative data, either experimental or theoretical, are available on the acidities of dienes and polyenes. Accordingly, this chapter will review recent work on the acidities of alkenes and the data available on dienes and polyenes will be placed in this context. 

Arnold s group has exploited the acidity of alkene cation radicals which have allylic hydrogens to isomerize an alkene function from a position in conjugation with an aryl ring to the position once removed from its original placement (Scheme 63)... 

Acidity of alkenes and polyenes Calculated ionization energies and eneigy changes for several reactions ... 

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