Final Flashcards
(169 cards)
1
Q
Electromagnetic radiation has properties of ?
A
particles and waves
2
Q
product of frequency of wave and wavelength is?
A
speed of light
3
Q
energy of each photon is ? to freq
A
proportional. E = hv
4
Q
freq and wavelength are ?
A
inversely proportional
5
Q
IR gives info about
A
functional groups
6
Q
NMR gives info about
A
C-H chemical env
7
Q
energy is not a continuum but exists at
A
discrete energy levels
8
Q
energy diff between energy levels is
A
quantized
9
Q
the molecule absorbs light when the phton has the energy that corresponds
A
exactly to delta E
10
Q
functional groups are detected by Ir bc each bond type has a
A
characteristic delta E between vibrational states based on bond strength and length
11
Q
Ir spec if a plot showing the
A
absorption of energy against freq of light
12
Q
relationship between wave number and mass
A
lower mass = larger wavenumber or freq
higher mass = lower wavenumber or fre
13
Q
relationship btwn bond strength and wavenumber
A
stronger the bond, the higher the force constant so the larger the wavenumber or freq
14
Q
trend for wavenumbers in general from large to small
A
X-H then triple bonds then double bonds then single
15
Q
relationship between wavenumber and hybridization
A
sp has higher then sp2 then sp3
16
Q
relationship between wavenumber and ring strain
A
inc ring strain = larger wavenumber
17
Q
relationship between wavenumber and conjugated systems
A
more resonance = lower wavenumber bc more single bond character
18
Q
what 2 factors impact signal intensity
A
bond polarity and number of identical bonds present
19
Q
relationship between dipole moment and signal intensity
A
more polar = stronger signal
20
Q
relationship between number of identical bonds and signal intensity
A
more identical bonds = stronger signal
21
Q
distribution of O-H bonds give rise to a
A
broad signal bc of H bonding
22
Q
secondary amines have how many N-H signals?
A
1
23
Q
primary amines have how many N-H signals?
A
2
24
Q
mass spec is used to determine the ? of a molecule
A
molecular weight
25
e- impact ionization method uses a high energy e- which
strikes a vaporized molecule
26
Mass spec: energy rich molecule ejects an e- forming a + odd electron species called the
molecular ion (radical cation)
27
molecular ion passes btwn poles of a magnet and is deflected by the
magnetic field
28
Mass spec: which molecules get deflected more, smaller or larger?
smaller
29
intensity of peak is proportional to
percentage of each ion of diff mass in the sample
30
what is the molecular ion
molecular mass of the molecule minus an e-
31
what is the base peak
most abundant peak - 100% relative intensity
might not be the molecular ion peak
32
if base peak = molecular ion peak, then
no fragmentation occurred
33
what is the (M+1)+. peak
measures C-13
inc intensity w inc number of C
34
Characteristic ratio for Br on (M+2) peak
1:1
35
characteristic ratio for cl on (M+2) peak
3:1
36
NMr involves interaction btwn
EM radiation and nuclei of atoms
37
nuclei with odd number of protons have an intrinsic
nuclear spin
38
the nuclear spin creates a
small magnetic moment around the atom
39
nuclear spins are normally at ? but are aligned by a ?
random orientations, strong external magnetic field
40
spin state alpha
aligned w magnetic field, lower energy
41
spin state beta
against magnetic field, higher energy
42
when Em radiation is applied, nucleus in alpha spin state
absorbs energy of photon and flips to beta state
43
the difference in energy between alpha and beta spin states
is small and dependent on B0.
44
inc external magnetic field to
inc delta E between alpha and beta spin states
45
if a given nuclei has lots of e density, overall affect of b0 is weakened and the nuclei is said to be
shielded
46
if the nuclei has little e density, the nuceli is more affected by B0 and is
deshielded
47
downfield =
deshielded = less e- density = feels B0 more
48
upfield =
shielded = high e- density = feels B0 less
49
the main contributor to deshielding of vinylic and aryl protons is the induced magnetic field associated with pi electrons. what is this called
anisotropy
50
does anisotropy reinforce or oppose B0
reinforces
51
the intensity(not height, but area under signal) of NMR peak is dependent on
the number of chem equiv hydrogens giving rise to that signal
52
protons on adgacent carbons will interact and split eash other's singles into
mulitplets
53
chemical shift of a proton is affected by
magnetic moment of adjacent protons
54
what is a J value
distance btwn peaks of a split pattern
55
protons coupled to each other have the same
J value
56
when does complex splitting occur
when neighbors are not chem equiv.
57
trans Hs on an alkene has ? J value than cis protons
higher
58
if OH signal is present in NMR, it is a
bs betweem 0.5 and 5
59
Does CNMR have spin-spin splitting
no
60
what does CNMR tell u
ho wmany diff carbon types there are
61
isolated dienes have
at least 1 sp3C between the alkenes
62
the single bond beteen 2 conjugated alkenes is relatively
short
63
there is max orbital overlap and e- delocalization on a conjugated diene if the 2 pi bonds are
coplanar
64
the two coplanar forms of a conjugated diene are
s-trans and s-cis
65
for MO diagrams, number of sp2 C
= number of p orbitals and psi`
66
traits of pericyclic rxns
e- move in loop, aromatic-like TS, concerted
67
electrocyclic rxns must be
fully conjugated polyene undergoes ring closure
68
sigmatropic rearrangements
2 db not conjugated
one sigma bond broken, one formed
69
diels alder rxn
cycloaddition rxn of diene and alkene
alkene is a dienophile
ex of pericylic rxn
4+2 cycloaddition
mediated by heat
70
the diene must be in the
s-cis conformation to react
71
cis to diene-->endo-->
anti
72
trans to diene-->exo-->
syn
73
endo approach is favored bc of
orbital stabilization of hte TS
74
endo product has subst. pointing ? relative to longest bridge
down
75
symmetry allowed
Homo of diene matches with lumo of dienophile
76
photochemical rxn
promotes HOMO, LUMO stays the same
77
cope rearrangement
all C
78
claisen rearrangement
allyl vinyl ethers
favors ketone until a benzene is present
79
define aromaticity
special stability due to resonance delocalizationm of the pi e- in a cyclic conjugated system/cmpd
80
huckel's rule
planar
cyclic
fully conjugated
4n+2 e-
to be aromatic
81
to be antiaromatic must be
planar
cyclic
fully conjugated
4pi e-
82
in a frost circle, to be antiaromatic ...
singly occupied MO or antibonding MO occupied
83
benzylic halides react faster than primary and allylic halides bc of
TS stabilization by orbital mixing
84
In EAS, what acts as the nuc
benzene
85
what is the intermediatea called for the EAS rxns
cyclohexadienyl cation, or arenium ion or sigma complex
86
limitations to friedel crafts alkylation
only alkyl halides ccan reaact
benzene can't have strong EWG (NO2, CN, SO3H, ketones, aldehydes, CA, amides)
anilines do not undergo FCA- must protect with acyl chloride nd pyr
87
benefits of FC acylation
no ccat. rearrangement
88
if a subst. for EAS is activating, the rxn goes
faster
89
halogens are weak deactivators but are
o/p directing
90
aromatics more deactivated than a monohalobenzene cannot be
acylated or alkylated with FC. Add acyl gruop first
91
requirements for SNAR
LG, EWG O/P to each other
Benzene is e-phile
92
what is the intermediate for SNAR called
Meissenheimer called
93
the rate of SNAR inc w
-inc numbet of EWG
-what LG it is (F>Cl>Br>I)
94
Elimination addition requirements
LG
95
intermediate for elimination addition rxn
benzyne
96
nuc attack at a carbonyl happens at what orbital
pi*
97
when do imines form
primary amine + carbonyl
98
when do enamines form
secondary amine + carbonyl
99
thioacetals have an acidic proton that can be deprotonated with
nBuLi
100
what is a ylide
dipolar intermediate with opposite formal charges on adjacent atoms
101
wittig reaction is highly selective for
ketones and aldehydes
102
what will not react but are tolerated in a rxn with wittigs
esters, lactones, nitriles, amides
103
what are not tolerated at all with wittigs
acidic groups (alc, amine, CA)
104
wittig reagents from simple alkyl halides form the
Z alkene (kinetic product)
105
wittig reagents with adhacent carbonyls form the
E alkene (thermo product)
106
baeyer-villiger oxidation priority
H>3>2, Ph>1>methyl
107
grignards react with?
acidic H--> protect free OHs
108
what reagent selectively reduces CA in the presence of other carbonyls
BH3THF
109
stabilization of carbonyls depend on
resonance
110
most reactive CA derivation to least
acyl chloride, anhydrides, esters, amides
111
what reagent do u use to get single addition of a c nuc to an acyl chloride
gilman
112
addition of grignard to nitriles gives an
iminium
113
iminium is hydrolyzed to
ketone
114
how many equivalents of grignards is added to nitriles
1
115
keto form is most common, but ? is the reactive species
enol
116
enol form of carbonyl contributes to reactivity at
alpha c
117
2 reasons for inc acidity of carbonyls relative to alkanes
1- induction from O
2- after deprotonation, (-) of enolate ion is stabilized by resonance
118
are enols or enolates more reactive
enolates
119
what is an aldol addition
addition of one enolate of a carbonyl with a second carbonyl
120
what is the product of aldol condensation
alpha beta unsaturated ketone/aldehyde
121
what happens when aldol addition is under heat and acid
aldol condensation
122
what base to use for directed aldol addition
LDA
123
what is a claisen condensation rxn
enolate of one ester reacts w a second ester
124
the alkoxide that is used as a base is the same as the ester group to avoid
trans-esterification
125
what is dieckmann cyclization
intramolecular claisen condensation
126
for unsymmetric ketones, use LDA, THF, -78 for
least sterically hindered deprotonation
kinetic product
127
for unsymmetric ketones, use -OMe, MeOH
for subst. enolate
thermo product
128
the thermo enolate us formed under ? conditions
reversible, with alkoxide base in protic solvent and rt
129
kinetic enolate is formed by ? conditions
irreversible, with SB, aprotic solvent and cold
130
alpha, beta unsaturated ketones and aldehydes are prepared by
1. aldol rxns with dehydration of aldol
2. alpha halogenation of ketone or aldehyde followed by elimiation
131
strong basic nucs react at the carbonyl carbon
Grignards and LAH
kinetic favored
132
less basic nucs react at beta carbom
enolates, gilman, amines, thiolates, cyanide
therm0 favored
133
what is michael addition
conjugate addition of an enolate to alpha, beta unsaturated ketone
134
what is robinson annulation
michael addition followed by intramolecular aldol condensation
135
what is the LG in hoffman elimination
quaternary amine
136
hoffman elimiation gives what product
least subst. alkene
137
what is the LG for nitrosation of alkylamines for secondary and tertiary amines
diazonium cation
138
at C1 of an aldose, the carbonyl is an
aldehyde
139
if there is a ketone anywhere else besides C1, it is a
ketose
140
carbs are desugbated as D or L according to the sterochem of the highest numbered
chiral carbon of fischer
141
what are the 4 stereoisomers of the aldotetroses
D and L erythrose, D and L threose
142
stereoisomers of aldopentoses
ribose (all right), arabinose is only top. xylose is middle and lyxose is top 2
143
pneumonic for aldohexoses
all altruists gladly make gum in gallon tanks
144
numbers for aldohexoses
1 2 1,2, 3 1,3 2,3 1,2,3
145
aldohexoses
allose altrose glucose mannose gulose idose galactose talose
146
aldoses contain a ? and ? which react to form cyclic ?
aldehyde, alcohols, hemiacetals
147
define anomers
carb isomers that differ only in stereochem of anomeric carbon
148
subst that are right on the Fischer point ? and those on the left point ?
down, up
149
to go from fischer to pyranose
manipulate so last OH is vertical
150
what is mutarotation
alpha and beta anomers are in equilibrium and interconvert via open form when react w water
151
anomeric carbon of pyranose and furanose form of ketose has both a
OH and CH2OH
152
the anomeric effect stabilizes an EN subst. on the anomeric carbon by
orbital mixing
153
the axial subst. is stabilized by interaction of a non-bonding e= pair on the ring O with the sigma star orbital which
lowers the energy of the overall molecule
154
the EN group prefers to be
axial
155
glycoside formation
anomeric OH is replaced by some other subst.
156
in fischer glycosidation carbs react with
an alc in the presence of an acid catalyst
157
fischer glycosidation is thermo controlled and favors formation of
pyranose over furanose
158
anomeric effect causes ? stereoisomer to predominate over ?
alpha over beta
159
the glycosol donor...
has a LG and is the e-phile
160
the glycosol acceptor....
has one free OH and is the nuc
161
in deoxy sugars a OH group is replaced with
H
162
amino sugars have an amino group in place of a
OH
163
amino acids are
amphoteric
164
what is the pI
pH at which the aa exists largely in a neutral form
165
when pH < pI
aa is +
166
when pH > pI
aa is -
167
the amino group can be protected using
BOC (deprotect w TFA) or FMOC (deprotect w piperidine)
168
the c terminus is protected using
benzyl bromide (deprotect with H2, Pt)
169
why use DCC
activates COOH to accelerate amide bond formation
