topic 6 Flashcards
what is meant by a homologous series
a group of chemical properties and can be represented by the same general formula
what is meant by a functional group
a group of atoms responsible for the characteristic reactions of a particular compound
what is a structural isomer
one or more compounds that contain the same number and kinds of atoms but have a different arrangement
what is stereoisomerism
isomers that have the same molecular formula but a different orientation/ spatial arrangement
what is the limitations of free radical substitution in the synthesis of haloalkanes
formation of a mixture of products -> unwanted products
what are sigma and pi bonds and how does it apply to alkenes
alkenes have a C-C double bond which contains 1 pi and 1 sigma bond
restricted rotation in alkenes
what is a sigma bond
a bond formed by the direct overlap of orbitals which leads to a high electron density between the nuclei of both of the atoms
what is a pi bond
a bond formed by the sideways overlapping of orbitals with the electron density concentrated above and below
the plane of the nuclei
draw a diagram to show pi and sigma bonding in an alkene
what is an electrophile
an electron deficient species and accepts electrons from an electron rich species
seeks out a negative centre
how can alkanes be formed
what conditions does it require
alkene + hydrogen -> alkane
nickel catalyst needed
how can dihalogenoalkanes be formed
alkene + halogen -> dihalogenoalkane
how can halogenoalkane be formed
alkene +hydrogen halide -> halogenoalkane
how can alcohols be produced and what condition is needed
alkenes + steam -> alcohol
in the presence of an acid catalyst
halide could go to primary or secondary carbocation if added to asymmetrical alkene
how can a diol be produced and what conditions is needed
potassium manganate (VII) + alkene -> diol
in acidic conditions
what is heterolytic fission
when a covalent bond is broken, the shared pair of electrons are taken by one of the atoms
results in the formation of ions
what is a nucleophile
donates electrons
negative charges
seeks out a positive centre
what is the reaction of haloalkane with aqueous potassium hydroxide- draw the mechanism
produces alcohols
hydroxide ion acts as a nucleophile
halogenoalkane + aq silver nitrate in ethanol
alcohol
water= nucleophile
if you add silver nitrate -> gives silver halide
alcohol + phosphoric acid ->
alkenes + water
elimination reaction (eliminates water from alcohols)
made from H atom and OH group
conc. phosphoric acid-> acid catalyst
alcohol + PCL5
chloroalkane + HCL + POCL3
alkene + steam + the conditions the reaction required
alcohol
steam
phosphoric acid catalyst
300C
60-70atm
alcohol + red phosphorus + iodine
3iodoalkane + H3PO3
what is the mechanism for the reaction between a primary halogenoalkane + ammonia
halogenoalkane + potassium cyanide
nitrile
reflux
R-C (triple bond) N
halogen ion carbon chain length inc by 1
halogenoalkane + ammonia
primary amine
ammonia swaps place with hydrogen
ammonia- nucleophile
halogenoalkane + ethanolic potassium hydroxide
alkene
elimination reaction
reflux
alcohol + 50% conc H2SO4 +potassium bromide + condition
requires acid catalyst
1) 2KBr + H2SO4 -> HBr + K2SO4
2) alcohol + HBr -> bromoalkane + water
why does stereoisomerism occur
due to restricted rotation around the c-c double bond
why can alkanes be seperated by fractional distillation
alkanes have different boiling points due to different chain lengths
