Chapter 14 - Alkenes Flashcards
What is an electrophile?
A molecule which is attracted to areas of high electron density, such as the double bond in alkenes
How does an electrophilic addition reaction take place?
First, electron will move from the double bond to the partially positive atom (if there is one) and the bond in the electrophile will break to form a negative ion. This has broken the double bond and formed a carbocation, which in the second step will react with the negative ion formed from the electrophile to make a neutral compound with no charges or double bonds.
How is the major or minor product determined in electrophilic addition?
The major product is the product where the carbocation ion is formed on the carbon with more alkyl groups bonded to it (e.g tertiary carbons more stable than primary), but only in asymetric compounds
Why is there a major and minor product?
This is due to the positive inductive effect, because the carbon with more alkyl groups is able to pull more electrons down from its bond to stabilise itself when it is a carbocation
What is an addition polymer?
It is a polymer where all of the reactants only form one product
How do alkenes form addition polymers?
The double bond on each alkene breaks and is therefore able to form a bond with 2 other alkenes, forming an addition polymer
How are they named?
They take the name of the alkene, for example ethene, and then put it in brackets and add poly to the front, e.g poly(ethene)
What are plasticisers?
They are small molecules capable of getting in between the monomer in a polymer, reducing rigidity of the polymer
What is PVC and how is it modified by plasticisers?
PVC used to be called Poly(vinylchloride) but is now called poly(chloroethene), and it usually used to make things such as drainpipes, but with plasticisers can be used to make things such as aprons
