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Organic chemistry > exam 4 > Flashcards

exam 4 Flashcards

1
Q

IUPAC priority

A

alcohol, alkene, alkyne, haloalkane

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2
Q

numbering if both alkene and alkyne

A
  • number to give the first multiple bond the lowest number
  • if tie, give alkene the lower number
  • name as #-en-#-yne
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3
Q

radical

A
  • species that contain unpaired e-
  • single e- takes place of H (no 4 substituted)
    sp2, stereoisomers will form
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4
Q

radical stability

A
  • increases with substitution
  • vinylic, methyl, 1, 2, 3, allylic (next to =, but not touching), benzylic (next to benzene, but not touching)
  • most stable radical comes from breaking the easiest C-H bond
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5
Q

bond dissociation energy (BDE)

A

increase radical stability, decrease BDE/bond strength

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6
Q

homolytic bond cleavage

A

one bonding e- stays with each half of the molecule
R-R -> R. + .R

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7
Q

initation

A
  • radical formation via homolytic bond cleavage of weakest/lowest BDE bond
  • requires energy, heat or light
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8
Q

propogation

A
  • nonradical reacts with radical -> atom abstraction
  • forms new radical and new nonradical
  • radicals formed continue on in the reaction
  • product usually formed
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9
Q

termination

A
  • not included in reaction mechanism
  • 2 radicals recombine to form nonradical
  • not common or product forming
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10
Q

radical chlorination

A
  • proceeds unselectively, forms enantiomer mixtures based on radical selectivity (not good for retrosynthesis)
  • ratio of products depends on how many of each kind of H and relative rate of forming each radical intermediate
  • put Cl on every unique sp3 C
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11
Q

radical bromination

A
  • proceeds selectively, one product forms
  • Br only adds to more substituted C
  • if equal substitution, multiple products
  • endothermic, so more radical character in ts, so radical stability is more important
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12
Q

alkene radical bromination

A
  • H202 or peroxides (ROOR) initiates radical
  • antimarkovnikov, Br on less sub C
  • creates alkane with Br on less sub C
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13
Q

alkyne radical bromination

A
  • H202 or peroxides (ROOR) initiates radical
  • antimarkovnikov, Br on less sub C
  • creates trans alkene with Br on less sub C
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14
Q

alkyne + H2, metal ammonia/dissolving metal (Na(s), NH3(l), -78C)

A
  • reduce alkyne to trans alkene
  • radical mechanism makes more stable product
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14
Q

hydrohalogenation: alkene + HX

A
  • alkene attacks H+ and X leaves, X- attacks carbocation from both sides
  • markovnikov, X on more sub C
  • creates alkane with X on more sub C, with enantiomers
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14
Q

halogenation: alkene + X2, H2O

A
  • alkene attacks X which attacks back, other X leaves
  • H2O backside attack of halonium ion intermediate’s most sub C, stereochemistry inverted only here
  • base deprotonates H2O+
  • creates alkane with trans/anti addition of an X and an OH, with OH at most sub C
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14
Q

hydrohalogenation: alkyne + HX

A
  • alkyne attacks H+ and X leaves, another X- attacks more sub C
  • markovnikov, X on more sub C
  • trans/anti addition of H and X
  • concerted bc vinyllic (+ on =) carbocation is unstable
  • 1 eq: alkene with X on more sub C
  • 2 eq: alkane with 2 X on more sub C
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14
Q

halogenation: alkene + X2

A
  • alkene attacks X which attacks back, other X leaves
  • X backside attack of halonium ion intermediate’s most sub C, stereochemistry inverted only here
  • creates alkane with trans/anti addition of an X at each C of the double bond
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15
Q

halogenation: alkene + X2, CH3OH

A
  • alkene attacks X which attacks back, other X leaves
  • CH3OH backside attack of halonium ion intermediate’s most sub C, stereochemistry inverted only here
  • base deprotonates CH3OH+
  • creates alkane with trans/anti addition of an X and an CH3O, with CH3O at most sub C
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16
Q

halogenation: alkyne + X2

A
  • alkyne attacks X which attacks back, other X leaves
  • X backside attack of halonium ion intermediate’s most sub C
  • 1 eq: alkene with trans/anti addition of X
  • 2 eq: alkane with 2 X on each C
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17
Q

hydroboration oxidation: alkene + BH3, THF, NaOH, H2O2

A
  • alkene attacks BH2, H-BH2 bond attacks alkene
  • creates alkane with BH2 on less sub C (both enantiomers)
  • NaOH, H2O2 replaces BH2 with OH
  • antimakovnikov, BH2 is bulky
  • syn addition of H and BH2
  • creates alkane with OH on less sub C (with enantiomer)
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18
Q

hydroboration oxidation: alkyne + BH3, THF, NaOH, H2O2

A
  • alkyne attacks BH2, H-BH2 bond attacks alkyne
  • creates alkene with BH2 on less sub C
  • NaOH, H2O2 replaces BH2 with OH (enol)
  • enol undergoes tautomerization to form ketone
  • syn addition of H and BH2
  • internal alkyne makes ketone, terminal makes aldehyde
  • carbonyl on less sub C
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19
Q

hydrogenation/reduction: Alkene + H2, Pd/C

A
  • syn addition of H2 to less bulky face
  • less sub alkene reacts faster
  • creates alkane
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20
Q

hydrogenation/reduction: Alkyne + H2, Pd/C

A
  • creates alkane
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21
Q

hydrogenation/reduction: Alkyne + H2, Lindlar’s catalyst

A
  • creates cis alkene
  • syn addition
22
Q

oxymercuration-demercuration of alkene:
Alkene + Hg(OAc)2, H2O/THF, NaBH4

A
  • alkene attacks Hg, OAc leaves, Hg attacks back
  • H2O attacks more sub C of mercurinium ion, stereochemistry inverted only here, forming alkane with trans H2O+ and HgOAC
  • H2O depronates H2O, leaving OH
  • NaBH4 gets rid of HgOAc
  • creates alkane with OH on most sub C, with enantiomer
23
Q

alkyne + H2O, H2SO4, HgSO2

A

hydration:
- alkyne attacks H+, H2O attacks more sub C on alkyne
- creates alkene with H2O+ on more sub C and HgSO4- on less sub C
- H2O deprotonates H2O+, leaving OH on more sub C
- H3O+ gets rid of HgSO4, creating unstable enol
tautomerization:
- alkene attacks H+, creating carbocation with OH on +C
- OH attacks it’s bond, creating double bond to OH
- base deprotonates, creating carbonyl on more sub C (ketone)

24
Q

tautomerization

A
  • constitutional isomers that exist in equilibrium
  • enol is unstable, ketone is stable
  • H2O attacks more sub C, carbonyl ends up on more sub C
25
Q

acetylide anion: terminal alkyne + NaNH2

A
  • terminal alkenes acidic, deprotonation of H on terminal side by NH2-
  • creates acetylide anion (neg terminal alkyne), which is strong nu-
  • acetylide anion attacks electrophilic C of R-LG (SN2 reaction)
  • LG leaves, new C-C bond formed
  • also makes NaLG
26
Q

ozonolysis of alkenes: alkene + O3, Zn, H3O+

A
  • cleavage of double bond, add O
  • creates carbonyl
27
Q

ozonolysis of alkynes: alkynes + O3, H2O

A
  • cleavage of triple bond, add O, add OH to other ends
  • creates carboxylic acids
28
Q

oxidation of alkenes with mCPBA

A
  • mCPBA: H-O-O-C(=O)-R, RCO3H
  • alkene attacks O, O-H attacks back, O-O attacks O-C
  • creates cis/syn epoxide, with enantiomers, plus OH-C(=O)-R
29
Q

nu attacks

A

most sub C, because it’s the most E+

30
Q

:B

A

usually H2O

31
Q

resonance stablized

A
  • due to hyperconjugation
  • carbocation next to O, Cl, Br, I
  • allylic carbocation
  • allylic and benzylic radical
32
Q

carbocation intermediate

A
  • stability increases with substitution
  • sp2: protonation of alkenes
  • sp: protonation of alkynes, vinylic unstable
  • next to O or X: protonation of haloalkenes and enols
  • can undergo methyl/hydride shift during rearrangement
33
Q

carbanion

A

conjugate base of terminal alkynes

34
Q

heat of hydrogenation

A
  • lower heat for more stable alkene
  • more stable with substitution and trans
35
Q

hydration

A

addition of H2O

36
Q

hydrogenation

A

addition of H

37
Q

SN1

A
  • LG leaves,
  • nu attacks carbocation intermediate
  • creates mix of enantiomers where nu has replaced LG
  • 2, 3
  • weak nu/base, good LG
  • protic
38
Q

SN2

A
  • nu backside attack, LG leaves
  • inversion of stereochemistry
  • Me, 1, 2
  • strong nu
  • aprotic
39
Q

E1

A
  • LG leaves
  • base attacks beta H, C-H bond makes more sub, trans double bond
  • 2, 3
  • weak nu/base, good LG
  • protic
40
Q

E2

A
  • base attacks beta H, C-H makes more sub double bond, LG leaves
  • requires antiperiplanar geometry, H and LG are planar and anti
  • halocyclohexanes have H and X axial
  • Zaitsev: more sub/internal alkene will form
  • bulky base (tBuO): less sub alkene
  • 1 if bulky base
  • 2, 3 if strong nu
  • aprotic
  • strong base/nu
41
Q

what does base do to LG (NaOH)

A
  • eliminates LG, creates alkene
  • if 2 eq of base, creates alkyne
42
Q

NaOtBu

A

tri sub Br -> di sub alkene

43
Q

NaOCH3

A

good nu
replace Br with OCH3
LG to alkene

44
Q

PBr2/PCl2

A

Cl or Br replaces OH

45
Q

TsCl

A

OH to OTs, better LG
can be turned into alkene by base

46
Q

integration

A
  • area under peak
  • relative # of H in a particular environment
    Ex: 3H = CH3
47
Q

multiplicity

A
  • peaks = n + 1, n = # of neighboring H
  • peaks named singlet, doublet, etc.
    Ex: triplet = next to CH2
48
Q

chemical shift of H NMR

A

adjacent EN and more s character moves shift downfield (left)

49
Q

signals in H NMR

A

number of different H

50
Q

signals in C NMR

A

number of different C

51
Q

DEPT 135

A

CH2 as neg

52
Q

DEPT 90

A

CH

53
Q

chemical shift of C NMR

A

adjacent EN moves shift left
sp2, sp, sp3

54
Q

IR spectroscopy

A

functional groups

55
Q

mass spectroscopy

A

largest mass = mass of compound
mass of fragments

56
Q

alcohol + H2SO4

A

makes alkene, with more stable alkene as major product
E2

57
Q

alkene + H2SO4

A

alkane with OH on more sub

Organic chemistry (6 decks)

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