Halogenoalkanes Flashcards
Why do halogenoalkanes have a polar C-X bond?
Halogens are very electronegative
What is the solubility of halogenoalkanes like and why?
They are not soluble in water
Because the C-X bond is not polar enough
What are the trends in boiling point for halogenoalkanes?
Boiling point increases with chain length
Boiling point increases down the halogen group
Why do branched alkanes have a lower boiling point than unbranched alkanes
Smaller SA on branched so less points of contact, weaker VDW
What factors in halogenoalkanes affect the reactivity of it?
C-X bond polarity
C-X bond enthalpy
Due to the polarity of the C-X bond, what do we call the reagents attracted to the electron deficient C atom?
Nucleophiles
What happens to the bond enthalpy as you go down the halogen group + why?
Decreases
Electrons further away from halogen nucleus as electron shielding increases
What is a nucleophile
A negatively charged ion ion or species with a lone pair of electrons
What organic compounds can be made directly from nucleophillic substitution of a halogenoalkane?
Amine
Alcohol
Nitrile
What happens during an elimination reaction of a halogenoalkane
A hydrogen halide is removed from the molecule and a double bond is formed, forming an alkene
Describe an elimination reaction involving bromoethane and hydroxide nucleophile
OH- ion uses it’s lone pair to form a bond with 1 H atom on carbon next to C-Br bond. The H atoms are slightly delta +
Electron pair from C-H now become part of C=C
Bromine takes pair of electrons in C-Br bond and leaves as bromide ion
When OH- acts as a base, what type of reaction is it?
Elimination
What are the conditions for an elimination reaction of OH- on a halogenoalkane
Hot OH- in ethanol
What are the conditions for a substitution reaction involving OH- in a halogenoalkane
Cold OH- in water
When reaction a halogenoalkane with OH-, what 2 factors can determine that type of reaction?
Reaction conditions
Type of halogenoalkane (primary, secondary, tertiary)
