2.6 Halogenoalkanes Flashcards
What are halogenoalkanes?
Halogenoalkanes are organic compounds where at least one hydrogen atom on an alkane has been replaced by a halogen.
What is a nucleophile?
A nucleophile is a species that donates a lone pair of electrons in a reaction.
What do the displayed, structural and skeletal formulae of the halogenoalkane with the molecular formula C2H5X look like?
What is the difference between primary, secondary and tertiary halogenoalkanes?
What is produced when a halogenoalkane reacts with an aqueous alkali, like KOH?
An alcohol is produced.
The OH- ion acts as a nucleophile and a nucleophilic substitution reaction takes place.
What is formed when a halogenoalkane reacts with ethanolic potassium hydroxide? What type of reaction takes place?
An alkene is produced.
The reaction is an elimination reaction.
(One of the reactions)
What is formed when a halogenoalkane reacts with warm ethanolic ammonia?
An amine is produced.
Ammonia acts as the nucleophile in a nucleophilic substitution reaction.
What is formed when a halogenoalkane reacts with alcoholic potassium cyanide?
A nitrile is produced.
The cyanide ion acts as the nucleophile in a nucleophilic substitution reaction.
Write the chemical equation for the reaction between bromoethane and ethanolic potassium hydroxide
What reaction can be carried out to increase the number of carbons in the halogenoalkane chain?
Nucleophilic substitution of the halogenoalkane with a cyanide ion in alcoholic conditions.
The cyanide ion, CN-, contains a carbon atom so the carbon chain increases by one unit.
How can halogenoalkanes be qualitatively identified?
Add ethanolic NaOH or KOH, followed by nitric acid then aqueous silver nitrate solution to the halogenoalkane. If a halogenoalkane is present then a silver halide precipitate will form in the solution.
What colour precipitate will form when chloroethane is added to silver nitrate?
AgCl - White precipitate
What colour precipitate will form when bromoethane is added to silver nitrate?
AgBr - Cream precipitate
What colour precipitate will form when iodoethane is added to silver nitrate?
AgI - Yellow precipitate
What is the name of the mechanism for the reaction between a halogenoalkane and ammonia?
Nucleophilic substitution