Alkenes Flashcards
why are alkenes highly reactive
the double bond is an area of high electron density
what does the double bond result from
the overlap of the spare unbonded singly filled p orbitals present on each carbon atom in the bond
what does the overlap of the p orbitals produce
a cloud of electron density above and below the molecule forming a pi bond
what’s the rotation like around the c=c bond
there’s no free rotation around the c=c bond
what shape is the c=c bond and what’s the bond angle
planar
120°
what are the 2 types of isomers
structural
and
stereoisomers
give the definition for stereoisomers
same structural formula but different arrangment in space
give the 2 forms of stereoisomers
e-z isomerism (geometric)
optical isomerism
give 2 reasons for geometric isomerism to exist
- the restricted rotation about the carbon to carbon double bond
- 2 different atoms/groups attached to each carbon in the double bond
what is E isomerism
it means the 2 highest priority groups are on OPPOSITE sides of the double bond
what is Z isomerism
the 2 highest priority groups are on the SAME side of the double bind
how do we determine priority of groups for e-z isomerism
by looking at atomic number
the double bond is an area of high electron density therefore what is it attacked by
electrophiles
the double bond is an area of high electron density therefore what is it attacked by
electrophile
what are electrophiles
electron pair acceptors
learn all of electrophillic addition in notes bc it’s too much for flashcards
now
how many products are formed with symmetrical alkenes
1
how many products formed with unsymmetrical alkenes in electrophillic addition
2
a major product
a minor product
what’s the major product
forms the most stable carbocation
which carbocation is most stable: primary or tertiary
tertiary
what do the alkyl groups do to the carbonation
alkyl groups like methyl and ethyl groups are electron donating through the positive inductive effect.
the alkyl groups push electron density towards the positively charged carbon atom, helping to stabilise the carbocation
therefore more alkyl groups, more stability
what do the 2 carbocation intermediates lead to?
they lead to 2 products being formed ( a major and minor product)
are the products from unsymmetrical alkenes in a 50/50 ratio
no , the most stable carbocation will form more product
what’s the uses for poly(ethene)
plastic bags
washing up bowls
what’s the uses for poly(propene)
rope
