alkenes Flashcards
what types of alkenes molecules
unsaturated hydrocarbons
alkenes features
no rings
double carbon bond
hydrocarbons
general formula of alkenes
CnH2n
how to put number when naming alkenes
put number after prefix of longest chanin of carbons and before suffix ene
low number priority for methyl or alkene
alkene over methyl
main chain of alkenes
must include double bond
properties of alkenes
non polar
only have van der waal
as length increases number of electrons increases
melting and boiling point increases
insoluble in water
4 electrons in double bond
high electron density
what prevents alkenes from moving
double bonds
what bonds do double bonds have
sigma and pi bond
how can alkenes rotate
breaking pi bond
requires energy or photons
rotation of pi bonds
restricted
stererisomers
same structural formula but different spacial arrangments
structural isomerism
same molecular but different different structural
substituent
atom or group of atoms which could be replaced by a hydrogen atom
z isomer
substituents on same side of molecule
e isomer
substituents on different side of molecule
CIP rule
-look at end of bond with 2 substituents
one with higher atomic number gets priority
isomers with 4 substituents
look on both sides and see priority atoms
compare positions of substituents relative to each other
if tie consider atoms further away
how to test for alkenes
use reddish brownish bromine that turns colourless when added to solution with double bonds
product of reaction of alkene and bromine
alkene plus bromine- bromine is 2 carbon bromine and hydrogen molecule
equation for bromine and alkene reaction
alkene plus br2 = alkenebr2
equation of alkene and hydrogen bromide
alkene + HBr = alkene plus 1 H and Br
equation for alkene and sulfuric acid
alkene + H2SO4 = alkene plus H and S
intermediate molecule with electrophillic addition
carboncation molecule
ions of whatever
steps of bromine electrohpilic addition
-alkene with H-Br
-double bond arrow to H
-arrow from bond to Br broken
alkane with H and carbon cation
Cation arrow to Br-
oxygen hydrogen bonds
polar
steps of sulfuric acid mechanism electrophillic addition
-double bond of alkene to hydrogen of H2so4
-hydrogen oxygen bond breaks
-electron goes to oxygen
-alkane with carbon cation
-H2so4 without extra hydrogen and oxygen lone pairs
-oxygen pairs with cation cabron
-final product ethyl hydrogen sulfate
unsymetrical and symetrical alkenes
ethene symetrical
propene not
major product formed
when pi bond broken hydrogen or molecule bonds to carbon with more hydrogens
-can work out major product
minor product
small amount of substance formed
how are carbocations more stable
the more alkyl groups the carbons bonded to the n=more stable it is
alkyl is CH2 or Ch3
how do alkyl groups stabalise carboncations
donate electron density to positive carbon to stabalise
primary carbon cation
one alkyl group
secondary carbocation
2 alkyl groups
tertiary carbocation
3 alkyl groups or more
most stable
addition polymer
marcomolecule that can be broken down to make alkenes
vice versa
addition polymerisation
alkenes formed to make macromolecules
forces of macromolecules
intermolecular forces string because long molecules
how to name polymers
take name of monomer around brackets and add poly infront
double bonds in polyethene
none
all broken in polymerisation
why are polymers strong
lots of electrons
strong van der wall forces
forces between polymers
-dipole dipole
hydrogen bonds
van der waal
why does addition polymerisaiton take place
unsaturated alkenes less stable than saturated
how to draw polymers
draw double bonds together
-side chains above
take put double bonds
PVC
Cl more electronegative
partial negative charge
polar bond
-rigidity
dipole dipole
van der waal
flexible PVC
spacer which separates bonds of PVC
no dipole dipole
plastaciser
separates PVC
flexible
