Exam 4 Flashcards
1
Q
explain what is necessary for hydrogenation of alkenes/alkynes
A
H2
a catalyst
solvent
heat
pressure
2 equiv. if taking alkyne to alkane
2
Q
hydrogenation is (reduction/oxidation)
A
reduction
3
Q
heterogenous hydrogenation catalysts
A
Pd, Pt, Ni
4
Q
Wilkinson’s catalyst:
- formula
- type of catalyst
A
Rh(PPH3)3Cl
homogeneous hydrogenation catalyst
5
Q
homogeneous hydrogenation catalyst
A
Wilkinson’s
6
Q
hydrogenation with a metal catalyst is (anti/syn)
A
syn
7
Q
How to accomplish cis partial hydrogenation of alkyne?
A
Lindlar’s catalyst
P-2 catalyst
8
Q
Lindlar’s catalyst:
- formula
- use
A
Pd/CaCO3 + quinoline
used to hydrogenate alkyne to cis alkene
9
Q
P-2 catalyst:
- formula
- use
A
Ni2B
used to hydrogenate alkyne to cis alkene
10
Q
How to accomplish trans partial hydrogenation of alkyne?
A
metal ammonia —Li, Na, or K + NH3 or RNH2
11
Q
what is dissolving metal reduction?
A
partial hydrogenation of alkyne to give trans alkene
12
Q
temp needed for dissolving metal reduction
A
cold
13
Q
hydrogenation using radical mechanism
A
dissolving metal reduction; metal has one electron; attacks twice
14
Q
sodium borohydride reduction —solvents
A
water
alcohol
ethers
15
Q
LAH reduction —solvents you cannot use
A
water
alcohols
(reacts explosively)
16
Q
carbene structure
A
17
Q
carbene acts as (Nu/El)
A
either one!
18
Q
3 methods of carbene addition
A
1) diazomethane
2) SImmons-Smith
3) Alpha elimination
19
Q
Diazomethane reagent
A
20
Q
diazomethane conditions required
A
heat or light
21
Q
problems with diazomethane
A
very explosive & toxic
carbene can also insert into C-H bonds
22
Q
Simmons-Smith reagent
A
ICH2ZnI
23
Q
“figure 8” transition state
A
Simmons-Smith
24
Q
Alpha elimination reagent
A
haloform (CHX3)
OH-
25
gives cyclopropane with 2 halogens
alpha elimination carbene addition
26
carbene adds to ___ bond
double
27
byproduct of diazomethane reaction
N2
28
explain syn 1,2-dihydroxylation
addition of 2 OH across C=C bond to give diol
29
2 methods of syn 1,2-dihydroxylation
1) KMnO4 + OH- + H2O + cold
2) OsO4 + pyridine; NaHSO3 + H2O
30
KMnO4 in COLD
syn 1,2-dihydroxylation
31
KMnO4 in HEAT
oxidative cleavage of alkenes
32
syn 1,2-dihydroxylation TS & relationship to stereochem of product
5-membered ring structure - must be cis - therefore product is trans
33
problems with KMnO4 method of syn 1,2-dihydroxylation
lower yield
byproducts due to overoxidation in any heat
34
problems with OsO4 method of syn 1,2-dihydroxylation
extremely toxic, but yield is higher
35
in the syn 1,2-dihydroxylation reaction, a trans alkene gives _________; a cis alkene gives _________
trans: 2 enantiomers
cis: meso
36
2 methods of oxidative cleavage of alkenes
1) KMnO4 + OH- + heat
2) ozonolysis
37
different types of alkenes & products with KMnO4 oxidative cleavage
unsubstituted: gives carbonyl product + CO2
monosubstituted: gives carboxylic acid (when tx with H3O+)
disubstituted: gives ketone
38
different types of alkenes & products with ozonolysis
unsubstituted: gives formaldehyde
monosubstituted: gives aldehyde
disubstituted: gives ketone
39
more useful reagent for oxidative alkene cleavage
ozone
40
name of ozonolysis mechanism
1,3-dipolar cycloaddition
41
ozonolysis conditions
anhydrous
42
difference between KMnO4 and ozonolysis in oxidative cleavage of alkynes
there is none!
43
internal alkyne gives 2 ___________ upon oxidative cleavage
carboxylic acids
44
alkyne + KMnO4 + heat + neutral conditions -->
diketone
45
diketone formation TS
tetrahydroxy
46
reagents used to turn alkene into an alkyne
X2
2 mol NaNH2
47
double dehydrohalogenation involved in...
synthesis of alkyne from alkene by elimination
48
steps in synthesis of alkyne from alkene
alkene + X2 --> vicinal dihalide
+ 2 mol NaNH2 --> alkyne + 2 NH3 + 2 NaX
49
steps in synthesis of acetylene
geminal dihalide + 3 mol NaNH2 --> acetylide ion
+ acid --> acetylene
50
used to deprotonate acetylene
NaNH2
51
3 methods of polymerization
1) cationic
2) radical
3) anionic (rare)
52
3 steps for any method of polymerization
1) chain initiation
2) chain propagation
3) chain termination
53
explain cationic polymerization
acid (lewis or bronsted) + alkene --> C+
another alkene attacks C+
chain continues
conjugate base takes H+ from C+ and alkene forms at end of chain
54
explain radical polymerization
radical initiator: peroxide ROOR + heat/light --> 2RO-, homolytic cleavage
pi bond attacks radical, giving stabilized radical on C
Next pi bond attacks this radical and so on
chain terminates as an RO- attacks the C radical; RO ends up on both ends of chain
55
explain anionic polymerization
ester/nitrile (e- withdrawing group)
base catalyzed
anion attacks another substrate to give chain
56
super glue is an example of which kind of polymerization
anionic
57
"metathesis"
"change positions"
58
explain olefin metathesis
2 alkenes are cleaved and recombined
59
metathesis catalysts
Schrock & Grubbs
60
3 types of metathesis
1) cross metathesis
2) ring-closing metathesis
3) ring-opening metathesis
61
type of metathesis involved in polymerization
ring opening method
62
glycol
1,2-diol
63
how to form a Grignard?
RX + Mg in ether --> R-Mg-X
64
Grignard structure
RMgX
65
Grignard acts as a (C+/C-)
carbanion (Nu)
66
explain Grignard reaction
Grignard attacks backside of carbonyl
R of Grignard adds to carbon, giving (-) O
acid protonates O to give OH
67
Grignard rxn with acid chlorides and esters
2 equiv Grignard required
R adds twice
68
synthesis rxn for organolithiums
RX + 2 Li in Et2O, hexane, etc --> RLi
69
structure of organolithium
RLi
70
organolithium acts as (C+/C-)
carbanion
71
explain organolithium rxn
RLi attacks carbonyl
R attaches to carbon and carbonyl --> alcohol
72
explan organolithium rxn with acid chloride and ester
reacts twice just like Grignard
73
long name for Gilman reagent
Lithium dialkylcuprate
74
formation of Gilman rxn
R RLi + CuI --> R-CuLi-R
75
how is Gilman written
(R)2CuI
76
how to get from alkyl halide to Gilman reagent?
1) 2 Li
2) CuI
77
Gilman rxn with acid chlorides
R replaces X on starting material, giving Ketone, not alcohol
78
Gilman rxn with ester
none bitch!
79
Gilman reagents can undergo ____ reactions with alkyl halides
SN2
80
2 reagents for reduction of carbonyl & strength/use
NaBH4 -- weak -- ketones, aldehydes, acid chlorides
LAH -- strong -- ketones, aldehydes, acid chlorides, esters, carboxylic acids
81
explain hydride reduction of carbonyl
hydride attacks carbonyl
carbonyl becomes alcohol
if there is an acid chloride or an ester, that bitch gets kicked off and an alcohol is made (with LAH)
82
what is special about raney ni
reduces carbonyls, alkenes and alkynes in SM
83
6 methods of alcohol oxidation --> carbonyl
1) NaOCl + HOAc
2) NaOCl + TEMPO
3) Chromic acid (Jones reagent)
4) Pyridinium chlorochromate (PCC)
5) Swern oxidation
6) Dess-Martin Periodinate (DMP)
84
alcohol that cannot be oxidized
tertiary!!! bitch
85
TEMPO structure
86
what does TEMPO do to bleach
makes it a milk
87
VERY strong oxidizer of alcohols
Jones reagent (chromic acid)
88
2 ways to write Jones reagent (plus other condition in the stuff)
CrO3 + H2SO4
Na2Cr2O7 + H2SO4
89
3 methods of oxidizing alcohols that do the same damn thing
PCC
Swern
DMP
90
components of Swern reagent
1. DMSO + (COCl)2 + -60°C
2. Et3N
91
why is Swern better than PCC
less toxic for the environment and doesnt cause fucking CANCER like PCC does
92
DMP reagent structure
yeah memorize that. Bitch.
93
2° alcohol --> ketone oxidizing methods
6, all of them do this
94
1° alcohol --> aldehyde oxidizing methods
NaOCl + TEMPO
Swern
DMP
PCC
95
1° alcohol --> carboxylic acid oxidizing methods
NaOCl excess
Jones reagent
96
3 methods to convert alcohol to alkyl halide
1) HX method
2) PBr3 method
3) SOCl2 method
97
method to turn any ° alcohol into an alkyl halide
HX
98
can only turn 1° or 2 ° alcohol into alkyl halide
PBr3 or SOCl2
99
explain HX conversion of alcohol to alkyl halide
ROH + HX --> RX
100
if converting alcohol to alkyl chloride, use ______ reagent
ZnCl2
101
explain PBr3 rxn with alcohol
ROH + PBr3 --> RBr
inversion of stereochemistry!!
101
explain PBr3 rxn with alcohol
ROH + PBr3 --> RX
inversion of stereochemistry!!
102
explain SOCl2 rxn with alcohol
ROH + SOCl2 + pyridine --> RCl
inversion of stereochemistry IF you use pyridine!
103
formation of sulfonate ester rxn
ROH + TsCl + pyridine --> ROTs
104
alternatives to tosyl chloride
MsCl
TfCl
105
why is sulfonate ester reaction really useful
converts OH to OTs, and that's a bitchin' leaving group!
substitution or elimination y'all! it's seriously cool
106
sulfonate ester rxn with NaOH gives...
an alcohol with a flipped stereochemistry (because SN2 backside attack)
107
sulfonate ester rxn with NaBr gives...
alkyl halide
108
sulfonate ester rxn with LAH gives...
alkane (basically taking off the alcohol altogther)
109
sulfonate ester rxn with NaOCH3 gives...
ether
110
what do you need for Williamson ether synth?
a 1° alkyl halide
an alcohol that's been deprotonated
111
steps to williamson ether synth
1) deprotonate alcohol with strong base (NaOH, NaH)
2) add 1° alkyl halide
boom! you have an ether
112
how. tomake cyclic ethers???
intermolecular rxn with williamson ether synthesis ---- alcohol on one end of a chain, alkyl halide on the other, they come together and smooch O
113
reagent used for cleavage of ethers
HX, excess
114
explain HX cleavage. ofethers
the ether is chopped in half at the oxygen. Where the oxygen was on each piece, there is now X
115
HX cleavage of ether mechanism
ether O attacks H on HX
X- attacks less sub. C+; alcohol leaves, giving product #1
alcohol attacks H on HX again
protonated alcohol leaves; X- attacks C+, giving product #2
116
2 methods to form epoxides
1) mCPBA (peroxyacid)
2) halohydrin + base
117
when forming an epoxide it replaces a(n)...
alkene
118
cis alkene + mCPBA -->
cis epoxide
119
trans alkene + mCPBA -->
trans epoxide
120
if we have 2 alkenes in a SM, and we use 1 equiv. mPBCA......
epoxide forms on the most sub. alkene
121
reagents used in halohydrin method of epoxide formation
1. Br2 + H2O
2. NaOH + H2O
122
steps in halohydrin/base formation of epoxide
1) halohydrin forms across alkene
2) base deprotonates OH, and O- attacks adjacent C (on itself!!), kicking off the Br and giving epoxide
123
epoxide rxns are the addition of a (Nu/El)
nucleophile
124
2 types of epoxide ring opening
acid-catalyzed
base-catalyzed
125
how to get trans diol from epoxide
cis epoxide + H3O+ --> trans diol (enantiomers)
126
difference between acid/base catalyzed ring opening of epoxides
acid: addition on the most sub. C
base: addition on the least sub C
127
how to add carbons, or H, to epoxide rings?
carbons -- use Grignard
hydrogens -- use LAH
128
pinacol
1,2-diol/glycol
129
reagent used in pinoacol-->pinacolone rxn
H2SO4 in water
130
pinacol --> pinacolone rxn
one OH attacks hydrogen on sulfuric acid
protonated alcohol leaves
methyl shift on C+; other OH makes double bond to C
OH is deprotonaed by water, giving ketone
