Category Archives: chemistry

In case of unsymmetrical alkenes the addition of hydrogen halide takes place according to the markovnikov’s rule . During this reaction under markovnikov’s rule the positive part of the attacking reagent joins with the carbon with more number of Hydrogen and the negative part of attacking reagent joins with the more substituted carbon.

We can make haloalkanes from the alkenes by treating them with rhe hydrogen halides HX . Here the double bond is converted into single bond , hydrogen and halogen gets attached to the carbons involved in double bond.

By catalytic hydrogenation we can get the alkanes from the alkenes. The reaction takes place by reacting ethene with hydrogen in the presence of platinum and pladium and Rany nickel (active form of Nickel) Here is the reaction :-

The mechanism involves the following steps :- Step 1 :- In first step the polarity is developed on the bromine molecule , and the partial positive side of the bromine molecule attacks on the carbon atom of the double bond. This leads to the formation of carbocation. Step 2 :- In second step the negativeContinue reading “Mechanism for electrophillic addition reactions of alkenes”

Alkenes give electrophillic addition reactions because of the following reasons:- 1. The pie electrons of the double bond attract electrophiles . 2. The electron density is more on the C-C double bond , so the electrophiles preferably attack on it as compared to the electrophiles which are repelled.

In this reaction the decarboxylation of dicarboxylic acids take place . The potassium salts of dicarboxylic acid give alkene as the COO- group is removed as CO2 , this leads to the formation of double bond between two adjacent carbon atoms.

The complete mechanism takes place in three steps as shown below :- Step 1 :- Step 1 involves the release of Hydronium ion (proton) and then the attack of proton on the lone pair electrons of oxygen. By this way protonated alcohol is formed. Step 2 :- This step is slow and rate determining step.Continue reading “What is the mechanism of acidic dehydration of monohybrid alcohol ?”

By just heating in the presence of methanol we can get the alkene by treating the vicinal dihalides with zinc. Here Is the complete reaction:-

In these kind of reactions the Saytzeff rule is followed. Here is the reaction and its conditions:-

We can obtain the alkenes from alkyl halides by the Dehydrohalogenation. In this kind of reaction the halogen and hydrogen from adjacent carbon are removed to make a double bond in the presence of alcohlic KOH . The reaction is shown below.

It is a kind of reaction in which under suitable conditions of temprature and pressure a simple alkane can give various products. As shown below. Pyro means the heat and lysis means the breaking, so it is a process of breaking the alkanes in the presence of heat.

In this kind of reduction the alkynes are reduced with sodium in liquid ammonia. This leads to the formation of Trans alkenes.

By the partial reduction of alkynes we can obtain alkenes.