4. Haloalkanes & Alkyl Halides Flashcards
what is the classification of 1/2/3 haloalkanes based on
how many C are bonded to the C attached to the halogen
what are the 2 methods of preparing alkyl halides
halogenation of alkene
halogenation substitution with alcohol
what are the reagents involved when preparing alkyl halides from alkenes
HX or X2
what are the reagents involved when preparing alkyl halides from alcohols
SOCl2 or HX
what are the 2 reaction types that alkyl halides can undergo
substitution
elimination
how are Grignard reagents formed
alkyl or aryl halide + Mg/ether solvent
what is the reaction rate equation for Sn1
rate ~ [alkyl halide]
doesnt depend on [nucleophile]
what is the reaction rate equation for Sn2
rate ~ [alkyl halide] [nucleophile]
what classification of alkyl halides does Sn1 mechanism favour
3 > 2»_space; 1
favours more stable carbocations like 3
what classification of alkyl halides does Sn2 mechanism favour
1 and some 2
not 3
what is the stereochemistry involved in Sn1 mechanism
starting with either enantiomer always gives a racemic mix
what is the stereochemistry involved in Sn2 mechanism
chiral non racemic mix of alkyl halide leads to inversion of configuration resulting in chiral non racemic product
what reaction does E1 compete with
Sn1
what conditions favor E1 over Sn1
in terms of pH, temp and solvents
strong base
high temp
non nucleophilic solvent
what is the rate equation of E1
rate ~ [alkyl halide]
what is the rate equation of E2
rate ~ [alkyl halide] [nucleophile]
what classification of alkyl halides does E2 mechanism favour
3 > 2»_space; 1
can do 1 if it extends conjugation
what does E2 mechanism require in terms of pH
strong base
what mechanism will the reaction occur by if:
the alkyl halide is 1
the nucleophile is weak (eg H2O and CH3OH)
SN2
what mechanism will the reaction occur by if:
the alkyl halide is 1
the nucleophile is low basicity and stronger Nu (eg Cl-, Br-, I-, CH3COO-)
SN2
what mechanism will the reaction occur by if:
the alkyl halide is 1
the nucleophile is high basicity and strong Nu (eg OH-, NH3, CH3O-)
SN2
what is the general reaction mechanism for all 1* alkyl halides
Sn2
what mechanism will the reaction occur by if:
the alkyl halide is 2
the nucleophile is weak (eg H2O and CH3OH)
SN1 or SN2
what mechanism will the reaction occur by if:
the alkyl halide is 2
the nucleophile is low basicity and stronger Nu (eg Cl-, Br-, I-, CH3COO-)
SN2
what mechanism will the reaction occur by if:
the alkyl halide is 2
the nucleophile is high basicity and strong Nu (eg OH-, NH3, CH3O-)
Sn2 and E2
what mechanism will the reaction occur by if:
the alkyl halide is 3
the nucleophile is weak (eg H2O and CH3OH)
SN1 and E1
what mechanism will the reaction occur by if:
the alkyl halide is 3
the nucleophile is low basicity and stronger Nu (eg Cl-, Br-, I-, CH3COO-)
SN1 and E1
what mechanism will the reaction occur by if:
the alkyl halide is 3
the nucleophile is high basicity and strong Nu (eg OH-, NH3, CH3O-)
E2
when a haloalkane reacts to form an amine what reactants and reagents are required
NH3 conc, heat and sealed tube
or
NH3 dissolved in alc
when a haloalkane reacts to form an amine why can you not use aqueous NH3
as OH- cause alc to form as its a stronger nucleophile than NH2
when a haloalkane reacts to form a secondary amine what reactants and reagents are required
R-NH2
primary amine
when a haloalkane reacts to form an alcohol what reactants and reagents are required
aqueous OH-
eg in KOH or NaOH
what is produced when an haloalkane is reacted with NH3 conc/heat/sealed or NH3 dissolved in alcohol
produces an amine
what is produced when an haloalkane is reacted with a primary amine
secondary amine
what is produced when an haloalkane is reacted with aqueous OH-
eg from KOH or NaOH
alcohol and halide ion
what is the reagents and reactants required when haloalkanes form alkenes
OH- (alcohol) and heat
what is the reagents and reactants required when haloalkanes form alkenes
OH- (ethanol) and heat
note must be dissolved in alcohol, if it is simpky OH- aq then alcohol will be formed instead of alkene
in reaction of haloalkane substitution to form alcohol and elimination to form alkene what conditions favours substitution
low temp
dilute soln of Na/KOH
more H2O in solvent mixture
in reaction of haloalkane substitution to form alcohol and elimination to form alkene what conditions favours elimination
high temp
conc soln of Na/KOH
pure ethanol solvent
what is produced when a haloalkane reacts with OH-(ethanol) and heat
alkene
