Organic Chem Flashcards
1
Q
Dehydration of alcohol; mechanism?
A
Alkene; E1 or E2
2
Q
Bond dissociation energies b/t 2 elements depend on…
A
hybridization
sp3-sp3 < sp3-sp2 < sp3-sp
3
Q
Which hybridization has the highest bond dissociation energy?
A
sp (forms strongest bond ∴ releases the most energy when broken)
4
Q
smaller atoms form stronger/weaker bonds?
A
smaller atoms form shorter bonds → shorter bonds are stronger bonds
∴ smaller atoms form stronger bonds
5
Q
what type of alkene has the weakest bond? Why?
A
unsubstituted alkene (all H) - more substituted alkenes are more stable
6
Q
What is characteristics of stronger bonds?
A
- smaller substituents
- more EN substituents
7
Q
What is unique about the amide C=O and C-N bond?
A
Can act as both SB and DB
- shorter than normal C-N
- longer than normal C=O
8
Q
If amides were protonated, where would the proton go?
A
O
- most basic site
- resonance causes it to have partial neg charge
9
Q
Hybridization of amide C and N
A
sp2 (due to DB formed on some resonance structures)
10
Q
VSPER of amide
A
6 atoms are all coplanar (trig planar around C & trig planar around N)
11
Q
EDG makes things more basic/acidic?
A
Basic
12
Q
For something to be absorbed through respiration, it must be…
A
- gas
- liquid with low BP (high vapour pressure)
- NO H-BONDING
13
Q
What force (e.g. VDW, dipole, H-bond…) is experienced with interactions between 2 hydrophobic tails?
A
VDW
14
Q
Rate sp, sp2, sp3 in terms of acidity
A
sp > sp2 > sp3
15
Q
rate sp, sp2, sp3 in terms of basicity. Explain.
A
sp3 > sp2 > sp
DB draw electron density from the EN element
16
Q
Which element tends to be the most basic?
A
N
17
Q
Amines are very good…
A
nucleophiles
18
Q
pKa + pKb =
A
14
19
Q
aromatic amine
A
N must be in the aromatic ring
20
Q
degrees of unsaturation:
N
Halogens
O
A
Pretend each is H and change number according to…
N = +1
Halogens = -1
O = 0
21
Q
for IR, ↑cm-1 = __ energy. What does this mean?
A
↑
C=O is 1700
C-O is 1300
C=O bond has ↑energy ∴ stronger than C-O
22
Q
Conjugation
A
alternating DB and SB
23
Q
What is found around 1630 - 1600 cm-1?
A
Amide
24
Q
what is the wavelength of ester, ketone, aldehyde?
A
ester: 1735
aldehyde: 1725
ketone: 1710
25
Stronger covalent bond = ____ H-bond
weaker
26
Weaker bonds show up as a broad/narrow peak in IR?
broad
27
NMR: upfield = ?, downfield = ?
upfield: shielded (0)
downfield: deshielded (10)
28
NMR for benzene
singlet at 7.0 ppm
29
NMR value: carbox acid
10-12 (broad)
30
NMR value: aldehyde
9-10
31
NMR value: aromatic H
7-8
32
NMR value: vinylic H
5-6
33
NMR value: alkoxy H
3.5-4
34
NMR value: alpha-H
2-2.5
35
NMR value: para-substituted ring
7.0 (dd)
36
which ring substitution has the least amount of peaks for NMR?
para
37
C-NMR: substitution vs. ppm
tertiary = lowest ppm (right)
primary = highest ppm (left)
3 > 2 > 1
38
Ester + NaOH
Ester is hydrolyzed to form
- carboxylate
- alkoxide
(Ester will dissolve in NaOH if refluxed)
39
Diols are axial-equatorial / axial-axial / equatorial-equatorial?
axial-axial / equatorial-equatorial both works, but cannot be axial-equatorial
40
H-bonding in diol occurs...
between O of one OH and H of other OH
41
dipolar
have dipole moment
42
optical isomer
rotate light in diff directions
43
geometrical isomer
differences in DB or ring structure
44
enantiomer
Non-superimposable mirror images
| SR RS
45
Diastereomer
Non-superimposable non-mirror images
| SR RR or SS
46
configurational isomer
identical bonds with different spatial arrangement of atoms
47
(+) polarity = CW or CCW?
| (-) = ?
CW;
| CCW
48
does having a chiral center mean the compound is optically active?
no, meso compounds have symmetrical, opposite chiral centers that cancel out any rotation
49
max number of stereoismers
2^n (n = number of chiral centers)
50
epimer
Deals with carbohydrates/sugars
| - chirality changes at only 1 C
51
Anomer
special type of epimer where only difference in chirality is at anomeric C. Straight chain form would be identical.
e.g. a-D-glucose vs. B-D-glucose
52
Anomeric C
C in sugar that is bound to 2 oxygens
53
protic solvents hinder ____
nuc that can H-bond
54
What stereochemistry does SN2 prefer?
less hindered
55
reaction kinetics of SN2
second order
| k[nuc][elec]
56
preferred solvent for SN2
polar, aprotic
e.g. ethers, ketones
57
A racemic mixture forms if SN_ reaction occurs and the reactant was ____
1;
| chiral
58
how to distinguish between substitution and elimination?
elimination usually requires higher temperature
59
physical properties of stereoisomers
enantiomers: identical physical properties
diastereomers: different physical properties
60
physical property of racemic mixtures vs pure enantiomers
racemic mixtures are generally more stable
- higher MP if solid
- higher density
61
which reaction happens faster: chlorination or bromination of alkane?
chlorination
62
what happens to product formation when energy is added into a system?
less stable compounds form to absorb excess energy
63
how to find number of structural isomers?
= number of unique C on alkane
64
E2 conditions
- basic
| - high temperature
65
E1 conditions
- acidic
| - high temperature
66
regioselectivity deals with...
Markovnikov's rule
The first substituent to be attached goes onto least substituted C
(e.g. Br would end up on more substituted C)
67
Stereoselectivity deals with...
Syn vs Anti
| Substituents likes to add to the least hindered face
68
1,2 addition to conjugated diene is under ___ control
kinetic (product depends on most stable INTERMEDIATE)
69
1,4 addition to conjugated diene is under ___ control
thermodynamic (product depends on most stable PRODUCT)
- higher temperature allows less stable intermediate to form
- rearrangement occurs to form more stable product
70
is the transition state of Diels-Alder reaction aromatic?
yes
71
the dienophile of a Diels-Alder reaction should have EWG/EDG attached to it to help the reaction proceed?
EWG
72
conditions for fastest Diels-Alder reaction
- EDG on diene
- EWG on dienophile
- Less bulky
73
pericyclic reactions
repositioning pi & sigma bonds through formation of cyclic intermediate
74
base unit of terpenes
isoprene (5C)
75
monoterpene has __ C
10C
76
which lab technique is used to separate terpenes?
steam distillation
77
process of steam distillation
1. pulp boiled
2. oil from pulp is distilled
3. distillate = water + terpenes
4. separate using extraction techniques
78
UV spectroscopy deals with...
pi bonds & conjugation
79
effect of branching on BP
more branched = decrease BP
80
alkoxide
good base?
good nuc?
C-O(-);
good base;
bad nuc
81
are ketones & aldehydes protic or aprotic solvents?
aprotic
82
is UV spectroscopy the same for aldehydes & ketones?
no, their pi-bonds are different
83
ketals & acetals are formed/removed under ____ conditions
acidic
84
hemiketals & hemiacetals are formed under ___ conditions, and removed under ____ condition
basic;
| any
85
is carbox acid a strong or weak acid?
weak
86
saponification
ester -> carboxylate (R removed from OR -> O-)
in the presence of xs. H2O and KOH
87
transesterification
exchange OR group on ester
88
acid anhydride synthesis from carb axid is a ___ reaction
dehydration (add heat)
89
are amides found in AA?
no, they are found in peptide chains! (peptide bond)
90
relative reactivity:
| acid halide, amine, ester, anhydride
acid halide > anhydride > ester > amine
91
each new C-O bond increases oxidation state by ___
+2
92
each new C-O bond increases oxidation level by ____
+1
93
Grignard reactions always have __ in the product
OH (alcohol)
94
when does grignard add twice?
when there is a LG on the C=O
95
is grignard a base/acid (strength?)?
| what type of solvent does it prefer?
strong base
| polar aprotic solvent (Et2O)
96
workup of grignard reactions use...
weak acid
97
what is removed during aldol condensation?
H2O (O comes from C=O of a second aldehyde or ketone, H2 comes from CH3 on R group of first aldehyde/ketone)
98
reactant and product of Claisen Condensation Reaction
R: ester + ester
P: B-ketoester
99
biological application of aldol condensation
4th step of glycolysis (retro-aldol reaction)
100
biological application of Claisen condensation
fatty acid synthesis
101
transesterification is driven forward by...
Le Chateliers
102
biological application of transesterification
fatty acid -> TG breakdown (saponification)
103
iodoform test is used for...
methyl ketones
104
methods in which aldehyde/ketone -> alkane
1) Clemmensen: Zn(Hg)/HCl [acidic]
2) Wolff-Kishner: NH2NH2 [basic]
3) SHCH2CH2SH + Raney Nickel [neutral]
105
most transition metals have __ oxidation states. This means that they are good ____ agents
```
+;
reducing agents (go from 0 to some positive number = oxidized)
```
106
Wolff-Kishner reaction is driven forward by...
removing N2
107
protecting groups for:
1) aldehyde
2) ketone
2) alcohol
1) acetal
2) ketal
3) silyl ether
108
match up:
| anabolism, catabolism, reduction, oxidation
```
anabolism = reduction
catabolism = oxidation
```
109
anabolism usually takes places in the ___ while catabolism takes place in the ___
cytosol;
| mitochondria (except glycolysis)
110
NADH is responsible for...
reduction of aldehydes & ketones
111
FADH2 is responsible for...
hydrogenation of pi-bonds
112
I2/OH is used to test for...
| Colour change?
methyl ketones
| yellow ppt
113
K2CrO4/H2SO4 is used to test for...
| Colour change?
primary & secondary alcohols
aldehydes
(orange -> green)
114
Br2/CCl4 is used to test for...
| Colour change?
alkenes
| brown -> clear
115
IBr/CCl4 is used to test for...
| Colour change?
unsaturated fats
| purple -> clear
116
derivative for aldehydes & ketones
2,4-dinitrophenylhydrazone
117
derivative for alcohols
benzylesters
118
derivative for osazones
sugars
119
In mass spec, Cl has what ratio?
3:1
120
in mass spec, Br has what ratio?
1:1
121
Parent peak in mass spec
Peak of highest mass (furthest right on the y-axis)
122
Base peak in mass spec
tallest peak in the whole graph (denoted as 100 for relative intensity; most intense)
123
mutarotation
flip-flop between a and B forms of ring (straight chain form is intermediate)
124
aldose ketose conversion occurs via ___ intermediate when acid catalyzed
enediol
125
aldose ketose conversion occurs via ___ intermediate when base catalyzed
enolate
126
glycosidic linkage is formed by a ___ reaction
hydrolysis
127
which polysaccharides branch?
amylopectin & glycogen
128
which polysaccharides are linear?
amylose & cellulose
129
what type of interactions are found between cellulose molecules?
H-bonding
130
____ linkages are usually responsible for branching in polysaccharides
1,6
131
Nitric acid oxidizes glucose to...
| Optically active?
glucaric acid;
| Yes
132
oxidized mannose =
| Optically active?
mannaric acid;
| yes
133
oxidized galactose =
| Optically active?
galactaric acid;
| No (the COOH on both ends makes it meso compound)
134
oxidized allose =
| Optically active?
allaric acid;
| No (the COOH on both ends makes it a meso compound)
135
Benedict's Test (Fehling's solution)
Test for reducing sugars (e.g. aldehydes) vs. non-reducing sugars (e.g. ketones)
+ test: blue -> red (there is a reducing sugar present)
136
Tollen's Test
Test for aldehydes (distinguish between aldehyde & ketones)
| + test: silver mirror forms (when aldehyde present)
137
Periodate oxidation
cleaves C-C bonds in sugar (will end up with a bunch of 1 C fragments)
- terminal C gains 1 bond to O
- internal C gain 2 bonds to O
138
Killiani-Fischer synthesis
increase C chain of aldose by 1 (cyano group added)
139
Ruff degradation
Remove 1 C from aldose (decarboxylation)
140
Wohl Degradation
remove 1 C from aldose (lots of N intermediates)
141
how to increase the length of aldose?
Killiani-Fischer synthesis
142
How to decrease the length of aldose?
Ruff degradation & Wohl degradation
143
what is the only oxidation step in glycolysis?
G3P -> 1,3 BPG
