Alkenes Flashcards
reaction of bromine with alkenes
-alkene–> dihalogenoalkane
reagent–: bromine
condition: room temp
mechanism: electrophilic addition
type of reagent: electrophile Br S+
reaction of hydrogen bromide with alkenes
alkene–> halogenoalkane
reagent: HCl or HBr
conditions: Room temperature
mechanism: electrophilic addition
type of reagent: H s+
Stage 1
Change in reaction of sulfuric acid with alkenes
Change in functional group
alkene –> alkyl hydrogensulfate
Reagents: concentrated H2SO4
Conditions: room temperature
Mechanism: Electrophilic addition
Type of reagent: Electrophile, H2SO4
CH2=CH2 + H2SO4 –> CH3CH2OSO2OH
Stage 2
Change in reaction of sulfuric acid with alkenes
Change in functional groupalkyl hydrogensulfate–>alcohol
Reagents: water
Conditions: warm mixture
Type of reaction: hydrolysis
CH3CH2OSO2OH + H2O –> CH3CH2OH + H2SO4
H2SO4 is best drawn in exams as
H-OSO2OH
role of sulfuric acid
catalyst
define hydrolysis
– a reaction where the molecule is split by the addition of water
define hydration
addition of water to a molecule
essential condition of direct industrial hydration of alkenes to form alcohols
-High temperature 300 to 600°CHigh
-pressure 70 atm
-Catalyst: concentrated H3PO4 ( Phosphoric acid)
what is addition polymerisation
Addition polymers are formed from alkenes
why is poly(alkenes) unreactive
due to the strong C-C and C-H bonds
describe the typical uses of poly(chloroethene) and how its properties can be modified using a plasticiser.
-In its pure form it is a rigid plastic due to the strong intermolecular bonding between polymer chains prevents them moving over each other.
-In this un-plasticised form it is used make uPVC window frame coverings and guttering.
If a plasticiser is added the intermolecular forces are weakened which allows the chains to move more easily, resulting in more flexibility in the polymer.
In this form PVC is used to make insulation on electrical wires, and waterproof clothing.
