Alkenes and electrophilic addition Flashcards
What is the geometry of, and bond angles in alkenes?
Trigonal planar
120 degree bond angles
What is the functional group in alkenes?
C=C
The carbon to carbon double bond
What is the hybridisation state of alkenes?
sp2 hybridised
each carbon has three sp2 hybridised orbitals and one unhybridised p orbital left to make a pi bond
State Markovnikov’s Rule in relation to alkenes…
When an asymmetrical alkene reacts with a hydrogen halide (H-X) to produce an alkyl halide, the hydrogen will add to the carbon that has the GREATEST number of hydrogen substituents. The halogen will add to the adjacent carbon which has the FEWER number of hydrogen substituents
In a mixture of HBr, adding what substance will result in Anti-Markovnikov addition?
Hydrogen peroxide (H2O2)
Adding Br2 to a test tube containing ethene will see what colour change?
From orange to colourless
(due to unsaturation of alkenes, Br2 will reaction with ethene to form di-bromoethane, using up the bromine hence the colour change)
State the conditions, and main product formed in the hydration of an alkene
An acid catalyst (e.g. H2SO4 sulphuric acid) and heat/high temperatures
Product = alcohol
What type of product forms from the bromination or chlorination of an alkene?
A dihaloalkane
In the electrophilic addition reaction between an alkene and a hydrogen halide, what type of product forms?
A monohaloalkane is formed
Hydrogenation of an alkene produces what type of hydrocarbon, and requires what type of catalyst?
Product = an alkane
A metal catalyst (e.g. Ni) is needed
Why can the C-C double bond in an alkene induce a temporary dipole on a non-polar molecule such as Br2?
Because the pi bond is a site of high electron density.
(As the Br2 gets close to it, the e- dense area of the alkene’s double bond repels the equally shared electrons in the Br2.
Thus, the Br atom closest to the alkene becomes partially positive, and the Br further away becomes partially negative, allowing the next step of the reaction to occur)
