5A.4 The Mechanisms of addition reactions Flashcards
what are full curly arrows
they are arrows that represent the movement of a pair of electrons
the high electron region in the C=C bond causes the alkene to be
attached to spices that are electron deficient
the curly arrow in addition to reactions must always
start from the bond or lone pair then to the atom
why do electrophiles attack alkenes
because electrophiles attack centers of negative charge which are found in the C=C bond
what is an electrophilic addition
it is a reaction where two molecules join into one molecule where the attacking molecule is an electrophile
what is a carbocation
it is a positive ion in which the charge is shown on a carbon atom
what happens in the electrophilic addition of hydrogen halides
step one: the hydrogen halogen covalent bond would break in heterolytic fission cause two atoms to go the the halide since it has a higher electronegativity. then the H+ ion would bond to the alkene by breaking the double bond ( the pi bond) this would form a carbonation
step 2: the Br- would represent has 4 lone pairs where one of them would react with the carbonation to form a halogenoalkane
what happens in the electrophilic addition of halogens
Br-Br isn’t a polar molecule but as it approaches the double bond it would repel the electrons in the Br-Br are pushed to the one further away from the alkene cause the alkene to induce the Br-Br making them polar
step 1: the hydrogen halogen covalent bond would break in heterolytic fission cause two atoms to go the negative halogen since it has a higher electronegativity. then the positive halogen ion would bond to the alkene by breaking the double bond ( the pi bond) this would form a carbonation
step 2: the negative halogen would represent has 4 lone pairs where one of them would react with the carbonation to form a 1,2-dihalogenoalkane
what is an asymmetrical alkene
it is an alkene where the atoms on either side of the C=C are not the same
what happens in asymmetrical electrophilic reactions
multiple compounds can form ie multiple isomers of the same compound
what is the difference between a major product and a minor product
a major product is made more than the minor one
what is a primary carbocation
a positive carbon that is joined to one alkyl group
what is a secondary carbocation
a positive carbon that is joined to two alkyl group
in asymmetrical addition of electrophile which compounds more stable and why
the one where the carbocation can spread its charge over more atoms (which usually makes a major product) that is because the alkyl is an electron releasing group
what are electron releasing groups
a group that pushes the electron towards the atoms is joined to
