Synthesis Flashcards
Organic Chemistry
what are alkenes?
unsaturated hydrocarbons containing at least one carbon to carbon double bond
why are alkenes so reactive?
the pi electrons are open to attack by electrophiles
how are alkenes obtained industrially?
by cracking the corresponding alkane
what are alkenes used for?
feedstocks for other chemicals such as:
*pharmaceuticals
*polymers
how can alkenes be prepared?
*dehydration of alcohols
*elimination of monoalkanes
what catalyst is used during dehydration of an alcohol?
sulfuric acid
what is hydrogenation?
when an alkene reacts with hydrogen to form an alkane and is catalysed by nickel
what is halogenation?
when a halogen reacts with an alkene in an addition reaction
what is hydration?
addition reaction of water across the double bond of the alkene to form an alcohol. catalysed by phosphoric acid
what is hydrohalogenation:
when a hydrogen halide is added to an alkene to form a monoalkane
what are haloalkanes?
homologous series of saturated carbon compounds containing one or more halogen atoms
what are haloalkanes used for?
*anaesthetics
*pharmaceuticals
*flame retardants
*solvents
how can haloalkanes be classified?
primary, secondary and tertiary
what type of molecules are haloalkanes?
polar covalent molecules
how do haloalkanes react?
the polar bond between the carbon and halogen is broken
what is the order of reaction in the haloalkanes?
iodoalkanes>bromoalkanes>chloroalkanes>fluoroalkanes
what are the two types of reactions that occur in haloalkanes?
substitution and elimination
what else can the slow step be called?
rate-determining step
what are the two types of substitution reactions?
SN1 and SN2
which types of haloalkanes are most likely to undergo an SN1 reaction?
tertiary haloalkanes
summarise what occurs in SN1 reaction:
slow step: polar carbon-halogen bond breaks, heterolytically, forming a negative halogen atom and carbocation intermediate. fast step: the intermediate can be attacked by a nucleophile from either side to form the product.
summarise what occurs in SN2 reaction:
the nucleophile forms a bond with the carbon attached to the halogen at the same time the carbon-halogen bond breaks resulting in a transition state. This will be trigonal bipyramidal shaped.
how are ethers formed?
when a monoalkane is reacted with alcoholic alkoxides
