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GAMSAT Chemistry organic reaction pathways > 4. Haloalkanes & Alkyl Halides > Flashcards

4. Haloalkanes & Alkyl Halides Flashcards

1
Q

what is the classification of 1/2/3 haloalkanes based on

A

how many C are bonded to the C attached to the halogen

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2
Q

what are the 2 methods of preparing alkyl halides

A

halogenation of alkene

halogenation substitution with alcohol

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3
Q

what are the reagents involved when preparing alkyl halides from alkenes

A

HX or X2

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4
Q

what are the reagents involved when preparing alkyl halides from alcohols

A

SOCl2 or HX

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5
Q

what are the 2 reaction types that alkyl halides can undergo

A

substitution

elimination

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6
Q

how are Grignard reagents formed

A

alkyl or aryl halide + Mg/ether solvent

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7
Q

what is the reaction rate equation for Sn1

A

rate ~ [alkyl halide]

doesnt depend on [nucleophile]

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8
Q

what is the reaction rate equation for Sn2

A

rate ~ [alkyl halide] [nucleophile]

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9
Q

what classification of alkyl halides does Sn1 mechanism favour

A

3 > 2&raquo_space; 1

favours more stable carbocations like 3

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10
Q

what classification of alkyl halides does Sn2 mechanism favour

A

1 and some 2

not 3

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11
Q

what is the stereochemistry involved in Sn1 mechanism

A

starting with either enantiomer always gives a racemic mix

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12
Q

what is the stereochemistry involved in Sn2 mechanism

A

chiral non racemic mix of alkyl halide leads to inversion of configuration resulting in chiral non racemic product

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13
Q

what reaction does E1 compete with

A

Sn1

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14
Q

what conditions favor E1 over Sn1

in terms of pH, temp and solvents

A

strong base

high temp

non nucleophilic solvent

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15
Q

what is the rate equation of E1

A

rate ~ [alkyl halide]

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16
Q

what is the rate equation of E2

A

rate ~ [alkyl halide] [nucleophile]

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17
Q

what classification of alkyl halides does E2 mechanism favour

A

3 > 2&raquo_space; 1

can do 1 if it extends conjugation

18
Q

what does E2 mechanism require in terms of pH

A

strong base

19
Q

what mechanism will the reaction occur by if:

the alkyl halide is 1
the nucleophile is weak (eg H2O and CH3OH)

A

SN2

20
Q

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-)

A

SN2

21
Q

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-)

A

SN2

22
Q

what is the general reaction mechanism for all 1* alkyl halides

A

Sn2

23
Q

what mechanism will the reaction occur by if:

the alkyl halide is 2
the nucleophile is weak (eg H2O and CH3OH)

A

SN1 or SN2

24
Q

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-)

A

SN2

25
Q

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-)

A

Sn2 and E2

26
Q

what mechanism will the reaction occur by if:

the alkyl halide is 3
the nucleophile is weak (eg H2O and CH3OH)

A

SN1 and E1

27
Q

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-)

A

SN1 and E1

28
Q

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-)

A

E2

29
Q

when a haloalkane reacts to form an amine what reactants and reagents are required

A

NH3 conc, heat and sealed tube

or

NH3 dissolved in alc

30
Q

when a haloalkane reacts to form an amine why can you not use aqueous NH3

A

as OH- cause alc to form as its a stronger nucleophile than NH2

31
Q

when a haloalkane reacts to form a secondary amine what reactants and reagents are required

A

R-NH2

primary amine

32
Q

when a haloalkane reacts to form an alcohol what reactants and reagents are required

A

aqueous OH-

eg in KOH or NaOH

33
Q

what is produced when an haloalkane is reacted with NH3 conc/heat/sealed or NH3 dissolved in alcohol

A

produces an amine

34
Q

what is produced when an haloalkane is reacted with a primary amine

A

secondary amine

35
Q

what is produced when an haloalkane is reacted with aqueous OH-

eg from KOH or NaOH

A

alcohol and halide ion

36
Q

what is the reagents and reactants required when haloalkanes form alkenes

A

OH- (alcohol) and heat

37
Q

what is the reagents and reactants required when haloalkanes form alkenes

A

OH- (ethanol) and heat

note must be dissolved in alcohol, if it is simpky OH- aq then alcohol will be formed instead of alkene

38
Q

in reaction of haloalkane substitution to form alcohol and elimination to form alkene what conditions favours substitution

A

low temp

dilute soln of Na/KOH

more H2O in solvent mixture

39
Q

in reaction of haloalkane substitution to form alcohol and elimination to form alkene what conditions favours elimination

A

high temp

conc soln of Na/KOH

pure ethanol solvent

40
Q

what is produced when a haloalkane reacts with OH-(ethanol) and heat

A

alkene

GAMSAT Chemistry organic reaction pathways (12 decks)

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