Final Exam Flashcards
(127 cards)
1
Q
atoms
A
made-up of protons, neutrons, and electrons
2
Q
protons
A
positively charged
found in nucleus
3
Q
neutrons
A
neutral charge/no charge
found in nucleus
4
Q
electron
A
negative charge
found in orbitals
5
Q
formal charge
A
labelling an atom. Defines the current number of electrons. Allows a comparison to the atoms position in the periodic table
FC=(#e- on PT)-[(#non-bonding e-)+(#bonds)]
6
Q
s-orbital
A
spherical, hosts 2e-
7
Q
p-orbital
A
dumbbell shaped, hosts 8e-
8
Q
sp3
A
all single bond hybridization one sigma bond free rotation 109 degrees *when creating an atomic orbital diagram combine all p and s into one row*
9
Q
sp2
A
one double bond hybridization one sigma and one pi bond no rotation 120 degrees *for atomic orbital diagram combine 2p and 1s into a row, one p will be leftover*
10
Q
sp
A
one triple bond hybridization one sigma bond and two pi bonds no rotation 180 degrees *for atomic orbital diagram combine 1p and 1s into a row, 2p leftover*
11
Q
constitutional isomers
A
have the same molecular formula but different in atom connectivity, different properties
12
Q
bond-line rotation
A
illustrates the carbon-carbon bonds in an efficient manner, carbons at “ends and bends”
- assume hydrogens when connected to carbons
- double and triple bonds shown
- -triple bonds are drawn straight
13
Q
the best to worst choices for movement of electrons
A
best=negative charge
good=lone pair
okay=pi bond
curved arrows show the movement of electrons
14
Q
resonance
A
movement of e-‘s within a single structure
- no atoms gained or lost
- resonance contributor structures help us visualize but are unrealistic
- -resonance hybrid is the reality and best representation
15
Q
common resonance patterns
A
allylic systems lone pair next to C+ a pi bond next to C+ a pi bond between two atoms of differing electronegativity a pi bond all the way around a ring
16
Q
guidelines for resonance structures
A
1) resonance structures involve the movement of electrons using curved arrows
2) don’t break single bonds
3) never exceed the octet rule. C’s okay to have 6e-‘s, just might be an issue with stability
4) a 6e- atom is less stable than an atom with a full octet (8e-)
5) minimize charges. bonds stabilize atoms and electrons. Choose structures with more bonds
6) electronegative atoms are best suited to host negative charges
17
Q
bronsted lowry acid
A
H+ donor
18
Q
bronsted lowry base
A
H+ acceptor
19
Q
lewis acid
A
e- pair acceptor
20
Q
lewis base
A
e- pair donor
21
Q
pKa
A
fixed value that defines the acidity of a functional group or molecule
-lower pKa=more acidic (strong)
22
Q
how to tell which is more acidic?
A
1) Identify the base and label it
- negative charge, lone pair, pi bond (SOURCE of e-)
2) Identify acidic hydrogen by highlighting polar covalent and (delta+/delta-). Label the most acidic hydrogen (as acid)
3) Draw curved arrows
4) Draw the outcome, conjugate acid and conjugate base
5) Assign pKa values to the acids
6) Favored side has a higher pKa value, weak acid/base side
23
Q
strong acid/strong base side has a (high/low) pKa
A
low
24
Q
weak acid/weak base side has a (high/low) pKa
A
high
this side would be favored
25
water-solubility
ions/charge: one charge (+ or -) will allow an organic compound to be more water soluble
h-bonding: one h-bond will help dissolve in water
26
ARIO
compare charged atoms
A=Atoms: electrognegativity increases across a row/size increases down a column
-more stable=more electronegative/larger size
R=Resonance: more resonance structures=more stable (except when comparing two O's and one O and 3 C's)
I=Induction: electronegative (increasing right and up on the PT) atoms drain e's away from negative charge
-closer=more stable-first to consider
-more electronegative=more stable-second to consider
O=Orbitals: hybridization (sp>sp2>sp3)
-electrons close to protons in nucleus=stabilizes charge
27
IUPAC Rules
1) Find the parent chain (longest chain) and name it
2) Name the substituents
3) Choose the numbering sequence with lower substituent number
4) Compile the name by organizing the substituents in alphabetical order. For multiple copies of one type use prefixes di, tri, tetra, etc...
28
Newman projection
way of viewing a bond
- can be Y or eiffel tower shaped
- can be staggered (anti/gauche) or eclipsed
29
newman projection with a dihedral angle of 60 degrees
staggered (anti/gauche)
| *anti is more stable than gauche, gauche is more stable than eclipsing*
30
newman projection with a dihedral angle of 0 degrees
eclipsed
31
cycloalkanes order of stability
worst to best
| cyclopropane
32
ring strain is composed of two factors
1) angle strain: deviation from ideal bond angle
| 2) torsional strain: angle strain can be somewhat relieved by forming "banana bonds"; however, these are weaker
33
chairs
axial bonds are parallel to edge of page; vertical
equatorial bonds are drawn to accent the tetrahedral geometry of each carbon
wedges=upper/up
dashes=lower/down
*bulky substituents prefer to be equatorial to minimize 1,3 strain*
34
cis
substituents on the same side
| Z=Zeisammen=together
35
trans
substituents on the opposite side
| E=eatgegen=opposite
36
stereochemistry
3D differences of molecules
37
stereoisomers are...
nonsuperimposable asymmetric moleucles
38
an asymmetric carbon is called a
chiralty center or stereocenter
39
a sterocenter is a carbon with:
1) sp3 hybridization
| 2) four different groups attached
40
enantiomers
non-superimposable mirror images (stereoisomers)
- to create an enantiomer you can either draw the mirror image or switch all dashes with wedges and all wedges with dashes
- will have the same physical properties and molecular forces (boiling point, melting point, Rf) but optical activity is differnt
41
diastereomers
stereoisomers with no mirror image relationship
- to create a diasteriomer only invert some of the stereocenters
- will have different physical properties and molecular forces (boiling point, melting point, Rf)
42
naming stereocenters with R/S nomenclature
1) assign priority to the four groups (around the stereocenter) based on best atomic number (a=highest priority and atomic number; d=lowest priority and atomic number-usually H)
2) place the lowest priority group in the back (on a dash)
3) assign layout of a, b, c
43
R nomenclature
clockwise
44
S nomenclature
counterclockwise
45
Drawing a stereocenter
guess and asses!
1) draw with lowest priority group on a dash
2) assess R/S
3) move two groups if wrong answer
46
optical activity
one way to differentiate enantiomers
- the plane is twisted either to the left or to the right
- -counterclockwise=levorotatory=1=(-)
- -clockwise=dextrorotatory=d=(+)
- optical activity can not be defined by R/S
- -R can be (+) or (-)/S can be (+) or (-)
47
racemate/racemic mixture
equal mixture of enantiomers
| -there is no optical activity for this sample because there is a 1:1 mixture of R/S and cancel each other out
48
mesocompound (mesomer)
one weird compound
| -does not have an enantiomer=mirror image is not a different compound
49
Identifying a mesocompound
1) presence of the same functional groups
2) do the stereocenters have opposite stereochemistry?R vs S
3) is there an internal mirror plane of symmetry
50
fischer projections
another way to draw stereocenters, helpful when drawing molecules that have many stereocenters, one after another
51
assign R/S to fischer projections
1) prioritize the bonds a, b, c, d based on best atomic number
2) lowest priority group in the back
3) determine R/S
52
1 carbon
methane
| methyl=substituent
53
2 carbons
ethane
| ethyl=substituent
54
3 carbons
propane
| propyl=substituent
55
4 carbons
butane
| butyl=substituent
56
5 carbons
pentane
| pentyl=substituent
57
6 carbons
hexane
| hexyl=substituent
58
7 carbons
heptane
| heptyl=substituent
59
8 carbons
octane
| octyl=substituent
60
9 carbons
nonane
| nonyl=substituent
61
10 carbons
decane
| decyl=substituent
62
transition state means
a bond is breaking and a bond is forming
63
high Ea means there is
a lot of upfront investment
64
low Ea means it is
an easier/faster rxn
65
concerted rxn
happens in one steps (E2 and Sn2)
| -1 hump on energy diagram
66
stepwise reaction
```
proceeds through intermeadetes
energy diagram:
-# of humps=# of steps
-# of valleys=#of intermediates
-highest energy=rate determining step
```
67
nucleophile
an ion/compound capable of donating electrons
68
electrophile
ions/compounds poor in electron density-can be attacked by nucleophiles-target for electrons
69
nucleophilicity
measure of how quickly a nucleophile will attack an electrophile
70
basicity
measure of the position of equilibrium for an acid-base rxn
71
carbocation
target for electrons (alkyl groups stabilize carbocations)
72
nucleophilic attack
characterized by a nucleophile attacking an electrophile
73
carbocation stability
```
the number of carbon neighbors
the empty p-orbital; immediate neighbors one bond away
-tertiary (3) carbocation-most stable
-secondary (2) carbocation
-primary (1) carbocation
-methyl carbocation-least stable
```
74
nucleophilic attack mechanism
characterized by a nucleophile attacking an electrophile
75
proton transfer mechanism
a base will remove a proton from (deprotonate) an acid
76
loss of a leaving group mechanism
leaving group is partially or completely removed
77
rearrangement mechanism
characterized by a change in the location of the electron deficient center (C+)
78
substitution
replace an atom (or group) with another Sn1 and Sn2 are common
79
elimination
two atoms are lost to form an alkene
| -reverse is addition
80
addition
add new atoms to an alkene
| -reverse is elimination
81
two reasons why alkyl halides are great substrates (reagents) for substitution
1) the electronegative atom polarizes the bond to the carbon
| 2) the halogen is a good leaving group (weak base). the halogen stabilizes the negative charge
82
Sn2
S=substitution
n=nucleophile, a good source of electrons is present
2=concerted, bimolecular, concentration of both the nucleophile and substrate impact the rate of rxn
83
Sn1
S=substitution
n=nucleophile
1=rate dependent on the substrate and its ability to form a carbocation stepwise with intermediates
84
if the concentration of substrates or nucleophile (or both) changes then will the rate of rxn change?
yes
85
are trans or cis isomers favored
trans isomers
86
Sn2 step(s)
one step with two arrows (inversion)
primary (1) or secondary (2)
-first arrow=lone pair on nuc forms a on
-second arrow=from a bond to form a lone pair on the LG
87
Sn1 step(s)
two steps with one arrow (racemization occurs)
secondary (2) or tertiary (3)
-step one=LG leaves, generating a carbocation
-step two=carbocation gets attacked by nucleophile
88
does the strength of the nucleophile affect both Sn2 and Sn1
no, it only affects Sn2, not Sn1
89
stong nucleophile (speeds/slows) an Sn2
speeds
90
weak nucleophile (speeds/slows) an Sn2
slows
91
(Sn1/Sn2) reactions are more sensitive to the leaving group
Sn1
92
_____of a carbocation determines the viability of an Sn1
stability
93
what is the rate determining step of an Sn1
the formation of the carbocation
94
what are good leaving groups
halogens
| a good leaving group effectively stabilized the negative charge
95
in Sn1 reactions the solvent...
1) helps to stabilize the leaving rgoup and carbocation formation
2) acts as the source of electrons to attack the carbocation
96
protic solvent
a solvent that has a proton connected to an electronegative atom
97
aprotic solvent
a solvent that does not have a proton on an electronegative atom (EX: acetone, DMSO, DME, DMF)
98
carbon neighbors help _____the p-orbitals
stabilize/support
99
the (more/less) neighbors=(more/less) stable alkane
more/more
| EX: tetra substituted>tri substituted>di (trans, cis, geminal) substituted>mono substituted
100
Naming alkenes
1) the C=C is the key functional group. We must unclude the C=C in the parent chain. Number through the C=C.
2) number fro the end of the molecule that gives the C=C the lowest number. Substituents are numbered after that.
3) Use E/Z to describe the stereochemistry
101
elimination reaction source of electrons
1) negative charge (Sn2/E2) (Na+-OCH/NaOCH3)
2) lone pair (H20 neutral) (NOT H+-OH) (Sn1/E1
3) pi bond
102
E2 process
a base removes a proton, causing the simultaneous expulsion of a leaving group (one step=no intermediates)
* only occurs on chairs when LG is axial*
* *bulky bases always perform E2 but do not follow Zaitsev's rule**
103
zaitzev's product
more-substituted
104
hoffman product
less-substituted
105
regiochemistry
where the rxn takes place
106
antiperiplanar
H and leaving group opposite on newman projection
107
E1 process
two steps where the leaving group leaves, forming a carbocation, and then a proton transfer occurs
108
E1
E=elimination to form an alkene
1=unimolecular, stepwise mechanism
rate dependent on the formation of a carbocation
109
markenvikov's rule
during an addition reaction the nucleophile to the more substituted side of the C=C
OR
the new H adds to the C with the more H's already, resulting in the more stable carbocation
110
oxymercuration/demercuration
an addition of water to an alkene that follows markovnikov's rule w/o carbocation rearrangements
111
catalysts
improve the rate of rxn by lowering the activation energy. the catalyst is regenerated at the end of the rxn
112
heterogenous catalyst
the substrate and catalyst are different phases solid (catalyst) vs liquid/gas (substrate)
113
homogenous catalyst
same phase
| EX: enzymes and sugars
114
epoxides
a paradox
ring strain=reactive
oxygen is a horrible LG
ether (C-O-C)=unreactive
115
```
urea is neutral. How many non-bonding electrons are present?
A. 4
B. 6
C. 8
D. another option
```
C. 8
116
Which of the following statements are accurate
curved arrows start at Lewis Bases
117
Which of the following functional groups are most water-soluble in a solution with a low pH
Amine
118
Which of the following statements is accurate when considering a cyclohexane chair ring flip?
A. during a ring-flip all chirality centers invert; R to S and S to R
B. equatorial bonds are usually R
C. bulky axial substituents are generally given top priority (a)
D. No change to R or S occurs
D. No change to R or S occurs
119
```
Which of the following would have the most stable conjugate base?
A. CH3CO2H
B. CH3C≡C-H
C. H-Cl
D. NaOH
```
C. H-Cl
120
```
An alkene is considered to be a weak acid (pKa=45). What else can you say about it?
A. it is a strong base
B. it has a strong conjugate base
C. it has a weak conjugate base
D. it has a strong conjugate acid
```
B. it has a strong conjugate base
121
```
What kind of energy is used to assess optical activity?
A. radiowaves
B. plane polarized light
C. microwaves
D. X-Rays
```
B. plane polarized light
122
```
which solvent is most likely to assist with Sn2 reaction?
A. tertiary
B. polar protic solvent
C. LDA
D. Acetone
```
D. Acetone
123
```
which of the following is commonly a way to perform an E2 reaction?
A. CH3OH
B. tButoxide
C. NaSH in DMF
D. water
```
B. tButoxide
124
```
What is the second step of the reduction reaction shown in question 3
A. substitution
B. elimination
C. acid/base
D. rearrangement
```
C. acid/base
125
```
what would happen to the rate of reaction if the 1-bromobutane concentration was doubled and the LDA concentration was doubled?
A. rate doubles
B. rate quadruples
C. no rate change
D. rate x6
```
B. rate quadruples
126
```
what describes the relationship of the elimination products for the reaction of 1R, 2S-1-chloro-1, 2-dimethylcyclohexane with sodium methoxide (NaOCH3)
A. Identical
B. Racemate
C. Constitutional Isomers
D. Diastereomers
```
C. Constitutional Isomers
127
Which statement is most accurate for D-(+)-glucose?
A. The D indicates the optical activity of the compound. It would rotate plane polarized light clockwise
B. D is another way of stating the chirality of the carbons, R=D
C. The (+) indicates that glucose is dectrorotatory
D. The D indicates a deuterium is present
C. The (+) indicates that glucose is dectrorotatory
