2. Alkenes Flashcards

1
Q

how many bonds and of what type are in C=C

A

1 x sigma
1 x pi

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2
Q

what hybridization does a C=C bond have

A

sp2

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3
Q

what shape and angle is a C=C bond

A

120*

planar

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4
Q

how are the 2 orientations of alkenes classified

A

E and Z

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5
Q

what are the orientation of substituents on an E alkene

A

Hi priority on opposite sides of the double bond

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6
Q

what are the orientation of substituents on a Z alkene

A

Hi priority on the same sides of the double bond

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7
Q

what are the cis/trans isomers

A

Cis = same group on same side of C=C

trans = same group on opposite side of C=C

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8
Q

what are the 2 ways alkenes can be prepared

A

dehydration of alcohols

dehalogenation of alkyl halides

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9
Q

what reagents and reactants are required in a dehydration reaction of alcohols to form alkenes

A

conc H2SO4

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10
Q

what reagents and reactants are required in a dehalogenation reaction of alkyl halides to form alkenes

A

KOH or NaOH(ethanol)

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11
Q

what is sayteffs rule

A

when >1 alkene can form the maj product is the alkene with the least # of H directly attached to C=C carbons

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12
Q

what are the 3 types of addition reactions that alkenes can undergo

A

hydrogenation

electrophilic addition

halogenation

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13
Q

what does hydrogenation of alkenes produce

A

alkanes

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14
Q

what does halogenation of alkenes produce

A

alkyl halides

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15
Q

what does electrophilic addition of alkenes produce

3 possibilities

A

alkyl halides/ethers/alcohols

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16
Q

aside from addition reactions what other 2 reactions can alkenes undergo

A

oxidation

polymerisation

17
Q

what reagent is involved when an alkene undergoes oxidation

A

MnO4-

can be with or without acid

18
Q

what is produced when alkenes undergo oxidation

A

prodi dihydroxyls

19
Q

what reagent is involved when an alkene undergoes hydrogenation (addition reaction)

A

H2/Pt

can also be with Ni instead of Pt

heat

20
Q

what stereochemistry are the H added in when an alkene undergoes hydrogenation to form alkanes

A

H added in syn

21
Q

what reagent is involved when an alkene undergoes addition reaction to form alkyl halides with -Cl

A

HCl(ether solvent)

to produce with -Br attachment can use HBr

22
Q

what reagent is involved when an alkene undergoes addition reaction to form ethers

A

ROH(alcohol)/H+

23
Q

what reagent is involved when an alkene undergoes addition reaction to form alcohols

A

H2O/H+

heat

24
Q

what reagent is involved when an alkene undergoes halogenation (addition reaction)

A

+ dihalogen
(eg Br2 or Cl2)

25
Q

what stereochemistry when an alkene undergoes halogenation to form haloalkanes

A

anti stereochemistry

trans formed

26
Q

when an alkene undergoes halogenation (addition reaction) what is the nucleophile and what is the electrophile

A

nucleophile = halide ion

electrophile = halogen

27
Q

what colour change is observed when Br2 reacts with an alkene

A

orange to colourless

28
Q

what colour change is observed when an alkene reacts with MnO4-/H+

A

purple to colourless

29
Q

what colour change is observed when an alkene reacts with MnO4- and no H+ catalyst

A

purple to brown precipitate

30
Q

what is a hydroboration reaction of alkenes in terms of products produced

A

produces alcohols

31
Q

what is a hydroboration reaction of alkenes in terms of reactants and reagents

A

B2H6/H2O2 and OH-

or

H2O/H+

32
Q

which reagent is needed for a hydroboration reaction of alkenes to produce a primary alcohol

A

B2H6/H2O2 and OH-

33
Q

which reagent is needed for a hydroboration reaction of alkenes to produce a secondary alcohol

A

H2O/H+