Organic: Alkenes Flashcards
how do you describe alkenes
They are unsaturated hydrocarbons, containing a double covalent carbon
The general formula is CnH2n
when cyclic CnHcn-2
high electron density so good nucleophiles
They react by adding across the double bond to form saturated compounds,
starts with ethene
describe the bonding within an alkene
sigma covalent bond- electrons between the two c atoms
pi covalent bond-electrons above and below the plane of 6 central atoms, this causes restricted rotation
there are many isomers of alkenes
give definition for structural isomers and geometrical isomers
structural- molecules with the same molecular formula but different structural formula -position - chain - functional group
Geometrical- E/Z isomers
explain the priority rules for E/Z isomers
look at the atomic numbers on both ends of c=c
highest values opposite= E
highest values together = Z
define electrophile
species that is positively charged, accepting an electron pair
explain the test for alkenes
bromine water which is orange is added to the sample. if the compound is unsaturated (alkene), an addition reaction will take place and the coloured solution will decolourise, forming dibromoalkane
explains Markownikoffs additions finding
The more alkyl groups on the carbocations the more stability so forms more of it, due to electrons push effect lead to more stability and easier form
order of stability of carbocations: tertiary>secondary>primary
so they are more likely to lead to teirtiery substituted products over secondary over primary. remember to answer with comparisions
explain what addition polymerisation is
Addition polymerisation is the reaction in which many monomers containing at least one C=C double bond form long chains of polymers as the only product.
he π-bond in each C-C bond breaks and then the monomers link together to form new C-C single bonds
why are the polymers non boidegradable
polyalkenes are made of strong non polar c-c and c-h bonds making them very unreactives so they are not affected by enzymes
remember
practise reactions for alkenes