haloalkanes Flashcards
what is a nucleophile
reagents that attack and and form bonds with + charged C atoms
- it is either a negatively charged ion or has an atom with a partial negative change (delta -)
- has a lone pair of electrons which it can use to form a covalent bond
what does a nucleophile have
lone pair of electrons with which it can form a bond by donating its electrons to an electron deficient carbon atom
- replaces the halogen in a haloalkane
- reactions are nucleophilic substitution follow same mechanism
why do nucleophiles attack halogens
polar bond means that the carbon atom has a small + charge which attracts substances with a lone pair of electrons
what does the rate of a nucleophilic substitution rection depend on
strength of the carbon - halogen bond rather the degree of polarization in the bond
what is a free radical
highly reactive species that have an unpaired electron
how does a free radical form
through homolytic fission of a covalent bond
the breaking of a bond is usually a high source of energy
e.g. UV light
what step involved the creation of the free radical species
initiation
what happens in initiation
requires uv light
- molecule = free radical 2A.
what happens in propagation
free radical A. + reactant molecule = product molecule + free radical B.
free radical B. + reactant molecule = product molecule + free radical A.
what happens in termination
free radicals = molecule
A. + B. = AB
what source of energy initiates free radical substitution
uv light
high temp
how can the rate of hydrolysis be measured
rate at which the precipitate appears
what do halogenoalkanes contain
1 or more halogen atoms substituted into an alkane molecule
uses of halogenoalkanes
pharmaceuticals e.g. anaesthetics ad in synthesising other organic compounds
how is ozone formed
naturally in upper atmosphere when uv radiation from sun breaks down oxygen into 2 o2 atoms (radicals)
combine with more oxygen to form o3
