Alkenes Flashcards
what is an alkene
unsaturated hydrocarbon with C=C double bond
what is the general formula of an alkene
CnH2n
why is there no rotation about the c=c bond
due to the pi orbitals electron density above and below the single bond which holds the atoms in place
are alkenes more or less reactive than alkanes and why
more reactive
due to high electron density of the double bond and the pi=-bond is slightly easier to break
what intermolecular forces of attraction do alkenes have
van der waals due to non polar bonds
are alkenes soluble in water and why
no as there are no polar bonds present and that means than van der waals are weaker then hydrogen bonds
name and describe the three kinds of isomers that alkenes can have
chain isomers
position isomers
geometric E-Z isomers
write and equation for the complete combustion of pent-2-ene
CH3CH=CHCH2CH3 + 71/O2 –< 5CO2 + 5H2O
what is an electrophile
electron deficient atoms/ions which accept a pair of electrons
what is the most stable type of carbocation intermediate and why
alkyl groups have a positive inductive effects so that most stable carbocation is the one bound to the most carbon
tertiary carbocation
what conditions are needed for the electrophilic addition of H2O to an alkene
acid catalyst H3PO4
what are the products of electrophilic addition of H2O to an alkene
an alcohol
draw a mechanism for the addition of water to ethene
CH2=CH2 ——> H+
H2O —–> CH3C+H2
CH3 CH2OH + H+
what are the conditions needed for the electrophilic addition of a hydrogen halide to an alkene
room temperature
draw a mechanism for the reaction for the reaction of HBr and ethene
refer to poster
what conditions are needed for the electrophilic addition of a halogen molecule to an alkene
room temperature and organic solvent
how does a molecule with a nonpolar bond react as if it is an electrophile
C=C double bond with a high electron density induces a temporary dipole in the halogen molecule and it attracted to the delta + in the double bond
draw a mechanism for the reaction between bromine and ethene
refer to poster
draw a mechanism for the reaction of sulfuric acid and ethene
refer to poster
how would you turn the product of sulfuric acid + ethene into an alcohol and how does this show that sulfuric acid catalyses the addition of water to an alkene
add water and the H2SO4 reforms showing it catalyses the hydration of alkenes
what is an addition polymer
many monomers bonded together via rearrangement of bonds without the loss of any atom or molecule
what are monomers
molecules which combine to form a polymer
draw how you would represent the polymerisation of ethene
n CH2CH2 —–> –[ -CH2 - CH2-]– n
give three uses of PVC
drainpipes
vinyl
aprons
