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CHEM 110 > Block 4 - Functional Groups I > Flashcards

Block 4 - Functional Groups I Flashcards

1
Q

types of halides

A

alkyl halides, vinyl halides (halogen to C in C=C), aryl halide

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2
Q

types of -OH containing compounds

A

alcohols, enols (-OH to C in C=C), phenol (aromatic ring)

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3
Q

classification of halides/alcohols exceptions

A

not used in aromatic rings or C=C ones as the C is not sp3 (but used in regular cyclic compounds - sp3 C)

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4
Q

need for classification

A

same functional group containing compounds display similar reactivity but specifics of HOW they react can be influenced by presence of neighbouring atoms

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5
Q

types of amines

A

alipathic (alkyl chain), aromatic (1+ bonds on N is to a ring)

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6
Q

classification of amines

A

number of C-N bonds there are (chemistry usually takes place at N)
- still used in aromatic amines

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7
Q

alcohol/amine solubility

A

soluble up to C5

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8
Q

alkyl halide solubility

A

non-polar => good organic solvents

- unsustainable

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9
Q

weak nucleophiles

A

neutral compounds containing O (O very electronegative so two lone pairs less available for reaction)

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10
Q

weak nucleophile examples

A

water, alcohols, carboxylic acids

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11
Q

moderate nucleophiles

A 
conjugate base (low basicity)
- negatively charged => decent nucleophiles
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12
Q

moderate nucleophile examples

A

halides, cyano anions, carboxylate anions

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13
Q

strong nucleophiles

A

high basicity

1) O with formal negative charge
2) C with negative charge (carbon-centred nucleophiles)
3) charged AND uncharged nitrogen species

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14
Q

O with formal negative charge

A

hydroxide, alkoxide (require very strong base to generate from alcohol)

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15
Q

C with negative charge

A

alkynide (deprotonated terminal alkyne - require very strong base to generate)

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16
Q

nucleophilic substitution

A

involves replacing one nucleophile with another

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17
Q

Good leaving groups

A

halides (Cl- < Br- < I-)

- better leaving group => faster reaction

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18
Q

poor leaving groups

A

H-, NH2-, HO-, RO-

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19
Q

SN1 unimolecular mechanism

A

1) halogen leaves to form carbocation intermediate (min. E) and halide ion (RDS)
2) nucleophile comes in
- two distinct steps

20
Q

SN1 rate

A

rate = k[RX]

- independent of Nu (strength of Nu may affect course of reaction but not rate as it reacts after RDS)

21
Q

SN1 favours

A

3º > 2º&raquo_space; 1º

+ benzylic halides (resonant stabilised carbocations)

22
Q

SN1 stereochemistry

A

loss of stereochemistry - either enantiomer gives racemic mixture as long as product is chiral

23
Q

SN2 bimolecular mechanism

A

concerted, synchronous - transition state (max. E) where bond partially formed and partially made

24
Q

SN2 rate

A

rate = k[RX][Nu]

- Nu involved in RDS

25
Q

SN2 favours

A

1º > 2º&raquo_space; 3º

unstable carbocations + less sterically hindered (crowded have raised energy of transition state and Ea)

26
Q

SN2 stereochemistry

A

inversion of configuration - non-racemic 2º alkyl halide results in non-racemic prod. of opposite chirality (simultaneous bond breaking/making so nucleophile must come in from other side)

27
Q

alcohols as Nu

A

alcohol (weak Nu) + strong base -> alkoxide (strong Nu)

- chemistry at O

28
Q

strong base

A

NaNH2

29
Q

alcohols as electrophile (E+)

A

alcohol (bad leaving group) + acid -> oxonium (good leaving group)

  • acidic conditions = limited nucleophiles as reagents as most are charged/basic
  • chemistry at C
30
Q

reagents and mechanisms for alcohol -> alkyl halide

A

tertiary: SN1 HCl
primary: SN2 SOCl2 (HCl too slow)

31
Q

amine + alkyl halide

A

product also amine which can act as nucleophile for another reaction

32
Q

product of sub. of amines

A

mixture of 1º, 2º, 3º and quarternary ammonium salts

33
Q

elimination

A

break sigma, form pi

- no classification as not adding/subbing nucleophile/electrophile

34
Q

alkyl halide -> alkenes

A

in presence of strong base

35
Q

alkyl halide -> alkynes

A

in presence of strong base

- dihalide -> alkyne

36
Q

alcohol elimination

A

in presence of strong acid
- alcohol -> alkene
NO ALKYNES from diols as enol intermediate unstable (forms corresponding carbonyl compound => tautomerises)

37
Q

E1 unimolecular mechanism

A

1) leaving group leaves to form carbocation
- extra step for alcohol -> oxonium
2) C-H bond breaks for C=C

38
Q

E1 rate

A

rate = k[RX]

39
Q

E1 favours

A

3º > 2º&raquo_space;> 1º

40
Q

E2 mechanism

A

leaving group departure and pi bond formation occur at same time

41
Q

E2 rate

A

rate = k[RX][Nu]

42
Q

E2 favours

A

1º alcohols, more complex for alkyl halides
- in reality no particular preference for 1º as steric hindrance not a problem (depends more on strength of Nu) so actually slightly prefers 3º more due to stability

43
Q

enantiomers

A

all stereocentres reversed

44
Q

diastereomers

A

only some stereocentres reversed

45
Q

mutorotation

A

spontaneous change in optical rotation observed when a pure anomer of a sugar is dissolved in water and equilibriates to an equilibrium mixture of anomers

46
Q

glycosidic bond/linkage

A

bond between anomeric carbon of one sugar and -OH group of another
- links two sugars together

47
Q

wheland intermediates

A

resonance stabilised carbocation intermediates

CHEM 110 (4 decks)

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