alkenes Flashcards
what are alkenes?
unsaturated hydrocarbons (contains a C = C double bond)
what is the general formula of alkenes?
CnH2n
which types of isomerism can alkenes adopt?
geometric stereoisomerism
positional isomerism
why are the physical properties of alkenes similar to that of alkanes?
Van der Waals are the only intermolecular force acting between molecules
how does reactivity of alkenes compare to alkanes?
alkenes are more reactive than alkanes because the C=C forms an area of high electron density which are easily attacked by electrophiles (electron pair acceptors)
what are most of the reactions of alkenes?
electrophilic addition
what is a test for an alkene?
add bromine water, solution goes from orange to colourless (decolourised)
what is the mechanism and conditions for making an alkene into an alkane?
TYPE OF ELECTROPHILIC ADD
hydrogenation (adding H2)
Ni catalyst
what is the difference between the products made during the electrophilic addition of alkenes with X2 or HX?
X2= dihaloalkane
HX= haloalkane
how is concentrated sulfuric acid used in a mechanism to make an alkene into an organic hydrogen sulphate?
electrophilic addition
H and OSO3H added
makes an organic hydrogen sulphate
this can then be hydrolysed to make an alcohol
how can alkenes be used in industry to make alcohol?
steam hydration (electrophilic addition)
involves adding H and OH
300 degrees, 60 atm and a concentrated phosphoric acid catalyst
what reactions can alkenes undergo to make polyalkenes?
addition polymerisation
why is hydrogenation of alkenes to make alkanes an important industrial process?
margarine is produced from the hydrogenation of fats or oils which contain C=C bonds
