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Org Chem 1 > Exam 4 > Flashcards

Exam 4 Flashcards

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1
Q

What are the trends of wavenumber?

A

Frequency increases with increasing bond strength (bond order 1-3) and higher percentage of s character
Decreases with increasing atomic mass and presence of conjugation

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2
Q

What is a 1200 cm-1?

A

C-C and C-N

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3
Q

What is at 1600 cm-1?

A

C=N (usually intense) and C=C aromatic (usually two skinny spikes, often have squigglies around 2000 and spikes just below 1500, tends to shrink sp2)

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4
Q

What is at 1620-1640 cm-1?

A

Conjugated C=C

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5
Q

What is at 1660 cm-1?

A

C=C (isolated 1640-1680)

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6
Q

What is at 1710 cm-1?

A

C=O of ketones, aldehydes, and carboxylic acids
+huge OH stretch - carboxylic acid
+2 C-H signals ~2700, 2800 aldehyde
(ketones & some aldehydes often have overtones beyond 3000)

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7
Q

What is at 1630-1660 cm-1?

A

C=O of amide

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8
Q

What is at 2200 cm-1?

A

C=-C <2200 with sp C-H 3300
C=-N >2200 no sp C-H 3300

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9
Q

What is at 2700cm-1?

A

First C-H spike of aldehyde

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10
Q

What is at 2800-3000?

A

sp3 and 2800- second C-H spike of aldehyde

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11
Q

What is at 3000 - 3100cm-1?

A

sp2

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12
Q

What is at 3300cm-1?

A

sp
OH when round
NH with spikes, secondary-1 spike, primary- 2 spikes (look for broad NH deformation around 1600)

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13
Q

If there is M+2 as large as M+

A

It is Bromine

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14
Q

If there is a M+2 a third as large as M+

A

There is a Chlorine

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15
Q

If there is a 127 large gap

A

There is an Iodine

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16
Q

If there is an odd M+ and some even fragments

A

there is a Nitrogen

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17
Q

If there is a M+2 larger than usual (4% of M+)

A

There is a Sulfur

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18
Q

Characteristics and function of molecular ions?

A

No fragmentation, usually highest mass and even-numbered.
The value of m/z for the molecular ion gives the molecular weight of the compound

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19
Q

What is fragmenation?

A

When instead of the radical cation (the molecular ion) there is a cation fragment (observed) and a radical fragment (not observed)
NOT Random: forms most stable fragments
Odd Numbered

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20
Q

Where do aromatic rings fragment?

A

At the carbon next to the aromatic ring (benzylic carbon)

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21
Q

How do ethers, amines, and carbonyl compounds fragment?

A

to give resonance stabilized carbons
Oxygen and nitrogen atoms have non-bonding electrons that stabilize positive charge

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22
Q

What about the molecular ion of alcohol?

A

It is often very weak or absent
There is a favorable loss of water and common fragment next to carbinol carbon atom giving a resonance-stabilized carbocation

Fragmentation: Alpha cleavage, form water (double bond) –> fragments again

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23
Q

What are the rounded masses of C, H, O, N, Cl, Br, I

A

C:12
H:1
O:16
N:14
Cl: 35
Br: 80
I: 127

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24
Q

What is the coupling constant 10 Hz?

A

cis

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25
Q

What is the coupling constant 15 Hz?

A

trans

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26
Q

What is the coupling constant 2 Hz?

A

geminal

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27
Q

What does the ball park range of 0-1.5 ppm indicate?

A

Alkane (changes with atoms surrounding)

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28
Q

What does the ball park range of 3-4 ppm indicate?

A

Hydrogens bonded to a C bonded to an halide

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29
Q

What does the ball park range of 5.5-6.5 ppm indicate?

A

alkene

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30
Q

What does the ball park range of 6.5-8.5 ppm indicate?

A

aromatic

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31
Q

What does the ball park range of 9-10 ppm indicate?

A

aldehyde

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32
Q

What does the ball park range of 12-13 ppm indicate?

A

carboxylic acid

33
Q

What does D2O do?

A

Gets rid of N-H or O-H bonds if present from NMR

34
Q

What do two peaks in the 7-8 range with the roofing effect indicate?

A

1-4 splitting in aromatic

35
Q

What are the three main things of 1H NMR?

A

Location: Know Ball Park ranges
Integration: Ratio between protons
Splitting: how many protons are adjacent (past quartet have protons on both sides)

36
Q

Relative deshielding of alkyne and carbonyl?

A

Carbonyl deshields more

37
Q

What are the aspects of the addition of HX to C=C?

A

Starting material(s)
Reagents/Conditions
Product(s)
Regioselectivity/Stereoselectivity/Additional Comments

38
Q

What are the aspects of the addition of HX to C=C?

A

Starting material(s): Molecule with double bond, HX (HCl/Br/I)
Reagents/Conditions: 1) pi attacks H (the electrophile) creating most stable carbocation
2) X- attacks carbocation as nucleophile
Product(s): H on one side and Br on the more stable carbocation side of the pi bond
Regioselectivity/Stereoselectivity/Additional Comments:
Two Steps, if rearrangement is possible it will happen
(will not be used in solution with water or get hydration of C=C)

39
Q

What is Markovnikov’s rule?

A

Electrophile will add to form the most stable carbocation

40
Q

What are the aspects of Hydration of C=C?

A

Starting material(s): pi bond molecule and H2O
Reagents/Conditions: In protic acid (making H3O)
Product(s): OH on more stable carbocation side and H on other where pi bond was
Regioselectivity/Stereoselectivity/Additional Comments: often use 50% H2SO4 & water, rearrangement occurs

41
Q

What are the aspects of hydration by oxymercuration-demercuration?

A

Starting material(s): pi bond molecule
Reagents/Conditions: 1) Hg(OAc)2/H2O 2) NaBH4
Product(s): OH on more stable carbocation side and H on other where pi bond was
Regioselectivity/Stereoselectivity/Additional Comments
1) creates OH and Hg(OAc) trans
2) replaces Hg(OAc) with H in exact same orientation
MUST put numbers for reagents

42
Q

What are the aspects of alkoxymercurization-demercuration?

A

Starting material(s): pi bond molecule
Reagents/Conditions: 1) Hg(OAc)2/HO-R 2) NaBH4
Product(s): OR on more stable carbocation side and H on other where pi bond was
Regioselectivity/Stereoselectivity/Additional Comments
1) creates OR and Hg(OAc) trans
2) replaces Hg(OAc) with H in exact same orientation
MUST put numbers for reagents

43
Q

What are the aspects of X2 to C=C?

A

Starting material(s): Halogen Usually Cl2, Br2, I2
Reagents/Conditions: pi bond attacks X and X e- attacks carbon and X bond e- move to other X –> X ion then X- attacks -> trans
Product(s): Trans X on either side of where pi bond was
Regioselectivity/Stereoselectivity/Additional Comments: trans, put both diastereomers/enantiomers

44
Q

What are the aspects of formation of halohydrins?

A

Starting material(s): X2/H2O
Reagents/Conditions Double bond attack X –> X ion, H2O attack partial positive charge, 2nd H2O attacks H on OH to remove +
Product(s): trans: X/ OH
Regioselectivity/Stereoselectivity/Additional Comments: Exactly the same as halogen addition but different Nu
**When this occurs in NaH (H: -) great base, bad Nu because make gas H2 creates epoxide

45
Q

What are the aspects of free-radical addition of HBr?

A

Starting material(s): HBr, ROOR
Reagents/Conditions: Heat
Product(s): anti-markovnikov H and Br (Br on lower priority C)
Regioselectivity/Stereoselectivity/Additional Comments:
R-O-O-R –> 2 RO*
RO* + HBR –> ROH + Br*
Pi + Br –> radical on higher priority C and Br on other side of where pi bond was
HBr attacks radical –> antimarkovnikov + Br*
Termination

46
Q

What are the aspects of hydroboration?

A

Starting material(s): 1)THF.BH3 2) H2O2, -OH
Reagents/Conditions: 1) pi attacks B H attacks C syn addition 2) BH2 replaced with OH
Product(s): Syn OH and H on higher priority carbon
Regioselectivity/Stereoselectivity/Additional Comments
Syn
3 alkenes to 1 BH3.THF

47
Q

What is a very common peroxide?

A

BPO: benzoyl peroxide
Ph-=O-O-O-=O-Ph

48
Q

What are the aspects of catalytic hydrogenation?

A

Starting material(s): Pi bond molecule
Reagents/Conditions: H2 (g) with catalyst (Pt, Pd, Ni, or Pd/c)
Product(s): No pi bond, syn Hydrogens on either side of where pi bond was
Regioselectivity/Stereoselectivity/Additional Comments:
Syn addition

49
Q

What are the aspects of addition of carbenes to C=C (Simmons Smith)

A

Starting material(s): Pi bond molecule
Reagents/Conditions: CH2I2/Zn (Cu)
Product(s): Molecule with syn addition cyclopropyl (Zn I, by product)
Regioselectivity/Stereoselectivity/Additional Comments: Syn addition

50
Q

What is a carbene? What are the three methods of making a carbene?

A

C with lone pair of e- and empty P orbital: Both wants and doesn’t want electrons –> cyclopropyl
1) Diazomethane H2C=N(+)=N (-)
2) Simmons-smith reagent: ICH2ZnI (carbenoid, more stable way to make carbene)
3) Alpha elimination: HCX3, haloform –> :CBr2

51
Q

What are the aspects of addition of carbenes to C=C? (alpha elemination)

A

Starting material(s): Pi bond molecule
Reagents/Conditions: HCX3, -OH
Product(s): molecule with three membered ring and X2 coming off of C
Regioselectivity/Stereoselectivity/Additional Comments
Syn addition, X remains in product

52
Q

What are the aspects of epoxidation?

A

Starting material(s): Pi bond molecule
Reagents/Conditions: Peroxyacids (Peracids)
Product(s): molecule with epoxide (& acid by product)
Regioselectivity/Stereoselectivity/Additional Comments
Syn

53
Q

What is an epoxide?

A

Three membered ring with an O in the middle aka oxirane

54
Q

What is the one peroxyacid you should know?

A

mCPBA
PhCO3
Ph 1-=O-O-O-H 3-Cl
Probably most common reagent

55
Q

What are the aspects of acid-catalyzed ring opening of epoxides?

A

Starting material(s): molecule with epoxide
Reagents/Conditions: Acid (mainly H3O) epoxide O picks up H, H2O attacks backside of most stable carbocation electron goes to epoxide O makes alcohol
Product(s): Trans alcohols where epoxide was
Regioselectivity/Stereoselectivity/Additional Comments:
Trans

56
Q

When a full carbocation is created…

A

Watchout for rearrangement

57
Q

What are the aspects of dihydroxylation?

A

Starting material(s): pi bond molecule
Reagents/Conditions: OsO4 and H2O2 or R3N(+)O(-)
Product(s): Syn OH on either side of where pi bond was
Regioselectivity/Stereoselectivity/Additional Comments: Syn addition
also could use permanganate: KMnO4 with -OH,H2O
same product

58
Q

What are the aspects of oxidative cleavage by KMnO4?

A

Starting material(s): Pi bond molecule
Reagents/Conditions: KMnO4, heat, conc.
Product(s): IF R groups only: ketones, If H groups: Acid
Regioselectivity/Stereoselectivity/Additional Comments
Created carbonic acid if two hydrogens to stay aldehyde to stay more reactant use ozonolysis

59
Q

What are the aspects of ozonolysis?

A

Starting material(s): Pi bond molecule
Reagents/Conditions: 1) O3 (-78*C) 2) Me2S or Ph3P (no smell)
Product(s): 1) create ozonide 2) created ketone and aldehyde
Regioselectivity/Stereoselectivity/Additional Comments

60
Q

What are the aspects of cationic polymerization?

A

Starting material(s): monomer with double bond
Reagents/Conditions: (electrophile) acid
Product(s): polymer (no cap) terminates with weak base elimination reaction
Regioselectivity/Stereoselectivity/Additional Comments

61
Q

What are the aspects of radical polymerization?

A

Starting material(s): Double bond monomer
Reagents/Conditions: ROOR’
Product(s): polymer with R-O- cap
Regioselectivity/Stereoselectivity/Additional Comments

62
Q

What are the aspects of anionic polymerization?

A

Starting material(s): Double bond polymer
Reagents/Conditions: -OH (something to make negative charge)
Product(s): polymer with OH cap
Regioselectivity/Stereoselectivity/Additional Comments

63
Q

What are the aspects of olefin metathesis?

A

Starting material(s): terminal double bonds
Reagents/Conditions: Shrock or Grubbs
Product(s): cis/trans combinations and = (ethylene gas)
Regioselectivity/Stereoselectivity/Additional Comments

64
Q

What are the types of olefin metathesis and what do they entail?

A

1) Cross Metathesis: break two terminal double bonds and put back together (crosses two molecules)
2) Ring Closing Metathesis (RCM): break two terminal double bonds on long chain and put together in ring (looses two carbons and creates ethylene)
3) Ring Opening Metathesis Polymerization (ROMP) break double bond in ring then polymerization fragments are on same side (i.e. both wedges)

65
Q

What is the name of the most simple alkyne?

A

acetylene (without 1 H acetylide)
Make sure triple bonds are LINEAR

66
Q

What is the relative acidity of H on ethyl, ethylene, and aceytlene?

A

Ethyl least, acetylene most acidic
because of increasing s character sp3, sp2, sp, 25%, 33% 50%
Most S character, more easily support carboanion

67
Q

What deprotonates acetylene?

A

NaNH2
It is a really strong base
(-)NH2 N attacks H on acetylene creating carbanion

68
Q

What is the carbanion of a triple-bonded carbon?

A

A great nucleophile that really likes to attack carboneals

69
Q

What is the most common synthesis of alkynes? What are the conditions?

A

Sn2, LG must be unhindered (must be a Me or 1*)

70
Q

What is one of the most versatile reaction organic chemists will see?

A

Addition of nucleophile to carboneal

71
Q

What are the different types of alcohols that can be made with triple-bonded carbanions?

A

R-=- : (-)
+ ketone –> 3* alcohol
+ aldehyde –> 2* alcohol
+ formaldehyde –> 3* alcohol

72
Q

How are alkynes made?

A

Dehydrohalogenation with dihalides either
1) vicinal (ie 1,2)
2) geminal (on same C)

73
Q

What are the common reagents to make alkynes?

A

(VERY STRONG BASES)
1) KOH fused with heat to continue slow second step
2) NaNH2 that will deprotonate alkyne to force the completion and fully make the product of a terminal alkynes (add H2O to protonate)

The first step is fast but the second is slow

74
Q

Major points of hydrogenation for alkynes?

A

Reactants: 2 eq H2 with Pt/Pd/Ni
Intermediate: Syn double bond
Product: Four H added where bond was
1) Stop at syn double bond
Lindlar’s catalyst Pd/BaSO4 and quinone and CH3-OH
2) Stop at trans double bond
NH3 (l) + Na*, strips electron from NH3
e- adds to double bond creates trans double bond (half arrow and double arrow) to keep e- pair and lone e- as far away as possible
e- pair attacks H-NH2, another e- adds , e- pair attacks H-NH2

75
Q

Major points of X2 addition to alkyne?

A

X2: cis/trans mix of 2 X across double bond
excess X2: four X where bond was

76
Q

Major points of addition of HX to alkyne?

A

Markovnikov
HX –> cis/trans mix
Excess HX leads to carbocation with resonance then geminal addition of two X

Anti-Markovnikov
HBr, ROOR, Heat leads to geminal addition of two X

77
Q

Major points of hydration of alkyne?

A

Markovnikov
HgSO4, H2SO4, H2O
(no work up step because acid supplies H)
forms enol and Hg 2+ (electrons taken from Hg to satisfy carbocation)
Enols do not like to exist
-Terminal alkyne –> ketone

Anti-Markovnikov (Hydroboration)
1) Sia2 BH 2) H2O2, NaOH to form aldehyde

78
Q

What do enols do?

A

They tautomerize to form a more stable ketone

Org Chem 1 (4 decks)

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