1
Q
What are diols and what is the different between vicinal and geminal diols?
A
Diols are alcohols with two hydroxy groups.
- Geminal diol has the hydroxy groups on the same carbon
- Vicinal diol have hydroxyls on adjacent carbons
2
Q
How are aldehydes named?
A
Replace -e of the parent alkane and replace it with -al
3
Q
How are ketones named?
A
Replace -e of the alkane with -one
4
Q
What are the common names for
Methanal
Ethanal
Propan_al_
Propanone
A
- Formaldehyde
- Acetaldehyde
- Propionaldehyde
- Acetone
5
Q
What does the suffix -oate indicate?
A
Ester
6
Q
What is the order of functional groups from highest to lowest priority
A
Carboxylic acid
anhydride
ester
amide
aldehyde
ketone
alcohol
alkene or alkyne
alkane
7
Q
What are three examples of physical properties?
A
- Melting point
- boiling point
- solubility
8
Q
How do conformational isomers differ?
A
differ in rotation around a single bond
9
Q
What is the difference between the anti and gauche conformation?
A
Anti: functional groups are 180 degrees apart
gauche: when two largest sub groups are 60 degrees apart
10
Q
What are the three strains that influence cyclic conformations?
A
Angle Strain: bond angle differ from normal because of being stretched/compressed
Torsional Strain: ecliped or guache interactions
Nonbonded strain: steric interactions
11
Q
What is one similarity and two difference between enantiomers and diastereomers?
A
both are nonsuperimposable
Diastereomers are not mirror images and enantiomers are mirror images
Diastereomers have different chemical and physical properties and enantiomers have the same except for rotation of plane-polarized light
12
Q
What are the two characteristics of a meso compound?
A
- chiral centers
- line of symmetry
13
Q
What is the one difference between E and Z designation? One simularity?
A
E: highest-priority substituents are on the opposite side of the double bound
Z: on same side of double bond
Both are diastereomers
14
Q
What are the two difference between Lewis bases and acids?
A
Lewis Bases are electron donors and are nucleophiles
Lewis Acids are electron aceptors and are electrophiles
15
Q
What type of bond do Lewis acids and bases form?
A
coordinated covalent bond: both electrons comes from the same starting atom (lewis base)
16
Q
What is the difference between base and nucleophile strength?
A
base strength is based on equilibrium and is a thermodynamic property
nucleophile strength is based on rates of rxn with electrophile so is a kinetic property
17
Q
What are the four factors that influence nucleophilicity?
A
- Charge: as electron density increases, nucleophilicty increases
- Electronegativity increases, nucleophilicty decreases
- Steric hinderance: bulkier, nucleophilicty decreases
- Solvent: protic solvents(have H+ attached to an element) can decrease nucleophilicty
18
Q
What are four factors that impact electrophilicity?
A
- increase positive charge, increase electrophilicity
- better leaving groups in species without empty orbitals, increases electrophilicity
- acids are strong electrophiles
- Anhydrides> caboxylic acids> esters> amides
19
Q
What is a heterolytic rxn?
A
opposite of a coordinate covalent bond
a bond is broken and both electrons are given to one of the two products
20
Q
How are nucleophiles and leaving groups related?
A
In substitution rxn, the weaker base (leaving group) is replaced by the stronger bases (nucleophile)
21
Q
What makes a good leaving group and how?
A
- Weak bases are good leaving groups (conjugate base of strong acids)
- Have resonance and inductive effects from e- withdrawing groups that delocalize and stabilize negative charge
22
Q
Why are SN2 stereospecific rxn?
A
There is an inversion of the relative configuration/ the configuration of the reactant is determined by the configuration of the product
23
Q
What is one difference between electrophilicity/nucleophilicity and acidity/basicity?
A
electrophilicity/nucleophilicity: based on rate of rxn so are kinetic properties
acidity/basicity: measure by position of equilibrium so thermodynamic properties
24
Q
What makes a good rxn site in a redox regent and nucleophiles/electrophiles?
A
- highest priority functional groups
- For nucleophiles, a good electrophiles is a more oxidized carbons so it has a larger positive charge since electronegative atoms are pulling e- density.
25
What are 4 strong oxidizing agent? What is one weak oxidizing agent?
1. KMnO4, K2CrO7, Cro3, Na2Cr2O7
2. PCC
1. PCC
26
What is one strong and one weak reducing agent?
1. LiAlH4 (reduce carboxylic acids)
2. NaBH4 (reduce aldehydes and ketone)
27
What is a phenol? What are the three possible arrangments of sustituent groups on phenol?
- hydroxyl groups attached to aromatic rings and the hydroxyl hydrogens are acidic due to resonance with phenol ring
1. ortho: two groups on adjacent carbon
2. meta: two groups separated by a carbon
3. Para: two groups on opposite sides of ring
1.
28
How can sustituents change the acidity of a phenol?
1. electron withdrawing groups increase acidity bc stabalize anion
2. electron donating groups decrease acidity
29
What is another name for vitamin K1 and vitamin K2?
Vitamin K1: phylloquinone
Vitamin K2: menaquinones
30
Name 3 facts about Ubiquinone?
1. Also called coenzyme Q
2. Most oxidized form and can be reduced into ubiquinol
3. conjugated rings to stablize molecule when carry an e-
31
What happens when you react an HCN with an aldehyde or a ketone?
Will get a cyanohydrin
32
What happens when aldehydes and ketons are treated with an excess amount of alcohol?
1. will get hemiacetal or hemiketal
2. acetla or ketal
33
What are two reasons hemiketals and hemiacetals are extremely short-lived?
1. The -OH group will rapidly become protonates in acidic conditions and is lost in water, which will leave behind a carbocation that will most likely be attacked by an alcohol
2. acetals and ketals are more stable because the added group is less likely to be protonated and leave compared to -OH
34
What is an enol?
carbon-carbon double bond and an alcohol
35
What are the 3 difference between the thermodynamic and kinetic enolate?
1. Kinetic is formed faster and is less stable. Thermodynamic product is formed slower but is more stable
2. Kinetic has a double bond to the less substituted alpha-carbon
3. Kinetic product is formed by the removal of alpha-hydrogen from less substituted alpha-carbon because it offers less steric hinderance. Thermodynamic product is formed by the removal of alpha-hydrogen from the more substituted alpha-carbon
36
What is the tautomer of an imine?
Enamines
37
What is saponification?
mixing fatty acids with lye (sodium or potassium hydroxide)--\> get a salt (soap)
-form micelles--\> long fatty acids with polar heads
38
Under what conditions will a carboxylic acids spontaneously decarboxylate (loss of CO2)?
When heated bc of stable cylic intermediate six member ring
39
Why is there an increased rate of hydroylsis in Beta-lactams?
because they are susceptible to hydrolysis due to high levels of ring strain, which is due to torsional strains and angle strain
40
What happens in transesterification?
exchange of one esterfying group for another in an ester (requires an alcohol as a nucleophile)
41
What are the three ways anhydrides can be cleaved?
1. addition of ammonia or an amine --\> amide and carboxylic acid
2. addition of alcohol --\> ester and carboxylic acid
3. addition of water--\> two carboxylic acids
42
How can cyclic anhydrides form spontaneously?
dicarboyxlic acids when heated
43
Why should esterification not be carried out in water?
Presence of water would likely revert the esters back into carboxylic acids and alcohol
44
What are 2 facts about IR spectroscopy?
1. measure absorption of infrared light, cause molecular vibrations
2. finger print region is between 1500 and 400 cm-1
45
What are 3 facts about UV spectroscopy data?
1. absorbance is plotted against wavelength
2. absorbance is caused by electronic transitions between orbitals
3. tells use extent of conjugation within a conjugated system with pi or nonbonding e (more conjugated, lower energy of transition, greater wavelength of absorbance).
46
What are two components of NMR?
1. chemicl shift: plotted on x axis and increases left(downfield)
2. TMS is used as a standard (0ppm)
47
What are 4 characteristics of Proton NMR?
1. peak height is proportional to number of protons
2. deshielding (attach to electronegative groups)/will be downfield
3. shielding: smaller ppm
4. iif a protons has n protons that are three bonds away, it will be split into n+1 peaks but do not include protons attach to O or N /mag of this splitting is called coupling constant J
48
Will enantiomers have the same IR spectra?
yes, because they have the same functional groups and will therefore have same absorption freq
49
What is superheating?
occurs when a liquid is heated to a tempature above its boiling points without vaporization
50
What is the difference between simple, vacuum, fractional distillation?
1. Simple: can be used if boiling points are under 150 and are atleast 25 degrees apart
2. vaccum: used if BP over 150 to prevent degradation of product. lower pressure so decrease temp liquid must reach to boil
3. should be used if BP are less than 25 degrees apart
51
How do you calculate Rf value?
Rf=(distance spot moved)/(distance solvent moved)
s
52
What are 4 traits of Gas Chromatography?
1. eluent is a gas
2. absorbent is a crushed metal or polymer
3. gaseous compounds travel at differnt rates bc they adhere to the absorbent at different degrees
4. inject components must be voltatile
53
What makes a carbon susceptible to nucleophilic attack?
protonate the carbonyl O, after it is attacked by nucleophiles, it will be protonated and leave as water so better leaving group
54
What is a conjugated system?
has alternating double bonds (alkenes)
55
What does mass spectrometry looks at?
mass-to-charge ration, remove e through ionization
56
what is a geometric isomer?
presence of double bond or ring
57
What will happen when two nucleotide triphosphates are bonding together?
release a small molecule called pyrophosphate, which will be hydrolized into an inorganic phosphate
58
If a group is attached to a strong nucleophile, will it leave overall structure?
No, large structure will have that group in it
59
How do you drive the synthesis of an anhydride?
using heat
60
What charge is the column for cation exchange?
column (stationary phase) is - charge
strong positive charges will elute last
61
What does aldol condensation look like? Can it be both base and acid catelyzed?
yes but need to have an alpha hydrogen
62
What does -anhydro mean?
removal of H2O
63
Is alpha hydrogen next to C=O more or less acidic?
more acidic because conjugate base is resonance stabilized
64
Are aldehydes more or less electrophilic than ketons?
aldehydes are more electrophilic because less electron donating groups
65
How does electronegativity impact acidity?
increases acidity becuase e- negative weaken the -OH bond
66
Where does electrophilic addition occur?
across double bond
67
Can ethanol act as a nucleophile?
yes
68
How can you reduce alkynes and alkenes?
H2 gas w/ Pt catalyst
69
How do electronegative atoms on phenol ring affect nucelophilicity?
contribute to e- density into resonance structure, so make a good nucleophile
70
How are imines formed?
nucleophilic attack of cabonly carbon with and amine
71
What synthesis is this? What does it form?
Stretcher Synthesis
amino acids
72
What synthesis is this? What does it form?
Gabriel Synthesis
Amino acids
73
What is a retro adol and what can it form?
1. two ketones
| (acid catalyzed)
74
How can you form an anhydride?
2 carbonxylic acids with H+ catalyst
75
What are 3 ways to form an amide?
1) react NH3 with anhydride--\> amide + carboxylic acid
2) ester + NH3--\> alcohol + amide
3. acyl halide + amine --\> amide
76
What are two ways to breakdown an amide?
1. Hydrolysis: H20+ amide + H+ catalyst--\> carboxylic acid + NH3
2. amide + reducing agent --\> amine
77
What is one way to form an ester?
1. transesterification
78
How do you form an acetal?
79
Do esters need protecting groups?
No, they are pretty stable
80
What agent converts carboxylic acids into acyl halides?
SOCl2
81
Are oxide anions and acyl reactive?
yes
82
Are bonds that are more polarized easier or harder to break?
easier
83
is C-N a good leaving group?
yes
84
What is the difference between a mesylate and a tosylate? what are their two purposes?
1. both have sulfer attached to O but tosylate has an aromatic ring attached and ussualy mixed with pyradine because good base
2. make -OH a good leaving group
3. they can also protect -OH groups from beaing oxidized into ketone or aldehyde
85
Are peroxides reactive?
very
86
How does the acidity change with increase substitution of alcohol?
highliy substituted makes it a weak acid but a strong base
87
What type of formation does phenol favor?
brominated products and use nonpolar solvent to get monosubstitution
88
What product do you get when you react a carboxylic acid with an ammonia?
ammonium (NH4+)--\> acid base reaction
89
What is the one product of an aldol condensation?
alpha, beta, unsaturated carbonyl
90
Is the keto form always perferred over the enol form?
yes
91
What does a cyanohydride look like?
c with triple bond to N
92
How much s character is from sp3? p character?
25% s and 75% p
93
What happens when an e absorbs energy from a photon?
moves from HOMO to LUMO
94
What does IR measure and what molecules will it not detect?
1. it measures the way in which the dipole moment of the bond vibrates over time
2. if symetrical, like a diatomic molecule with no dipole, no IR
95
What is the shift of 11.0ppm on H-NMR mean?
carboxylic acid --\> down field/deshielded
96
What do elimation rxn creat? what do they need?
1. double bonds
2. base catelyzed
97
How can you remove double bonds?
H2 + Pt (catalytic hydrogenation)
98
Why cant NH3 be a buffer if it is a weak base?
because it is a gas at room temp/would not use as a buffer for acidic solution
99
Is -OH a strong nucleophile?
yes
100
How do addition rxn impact sigma and pi bonds?
increase sigma, decrease pi
101
What do organic compounds need?
-CH bonds
102
What is an example of a protic solvent?
DMSO
103
What does tautamerization need?
need alpha atom to form double bond
104
Will alcohol protonate?
no
105
What is an imide?
one acyl group on either side of the nitrogen that ay be attached to an additional R group
106
What is an enamine?
is the the enol version of imine. double bond between two carbons instead of double bond between N and C (imine)
107
What are Gringard reactions used for?
used to alkylate a compound with a carbonyl
108
How might halogenation increase boiling point of an alkane?
Strongest intermolecular force are Lond disperision, but if halogenation, will have dipole-dipole interactions
109
Do alkanes have cis or trans conformation?
no, can rotate freely
110
For SN1, where would the most stable carbocation form?
most substitutes carbone with leaving group (halogen)
111
What is one requirement for a zwitterion?
have to have both positive and negative charges
112
Is a more stable conjugate base more or less alkaline?
less, have resonance structures to delocalize e density
113
If two chiral carbons and molecule has symmetry, how many meso compounds?
2
114
Out of the three, which one is chiral?
1. tert-butoxide
2. DMSO
3. Diethyl tartrate
3. Diethyl tartrate
115
Are cyclic hydrocarbons more or less nonpolar than linear hydrocarbons?
more
116
What are two rxns involving esters?
hydrolysis: H20 + ester + H+ catalyst--\> H3O+ + carboyxlic acid
reduction of ester --\> two alcohols
117
What condition is most ideal for recrystalization?
substance is highly soluble at high temp but insoluble at low temp and ppt forms
118
When does recrystalization need to be conducted?
if the measured boiling/melting point is extremely different from the expected boiling/melting point
119
What is the difference between NMR and IR?
IR (Infrared radiation--\> low energy radiation) involves absorption of light directly into chemical bonds, a process that occurs at a specific wavelength according to the bond type
NMR triggers a nuclear oscillation at a measurable frequency, use magnetic pulse to displace atomic nuclei
120
Are all monosaccharides reducing sugars?
yes
121
How can you drive the forward rxn of an anhydride from two carboxylic acids?
add heat
122
Do ketones make a compound more or less acidic?
less, bc contribute electron density to conjugate base
123
What is chromium trioxide ussualy used for?
oxidation rxn
124
How can a phenol undergo halogenation?
chlorine + H20(Protic solvent)
125
When is methane active?
in presence of strong base
126
What is sodium hydride?
strong base
127
How does protonation affect a rxn?
it makes a compound a better leaving group (ex: protonation of an alcohol makes a better substitutions of -OH)
128
How do you calculate enantiomeri excess?
Ovserved rotation / specific roation x100
129
How do you calculate Specific rotation?
obersvered rotation/ (c xL)
c(g/ml)
L(pm)
130
When is the alpha carbon acidic?
conjugate base is resonance stabilized, inductive effects are able to stabilze negative charge (withdraw electrons)
131
What is the value of an ionization constant of a weak acid?
close to 0
132
What conditions favor E1 rxn?
add heat
133
Do ethanols protonate?
yes, they are acidic
134
How can you form an acetal from a hemiacital?
acid conditions
135
What is pyridine?
weak base
136
What is a good buffer?
pka+/- 1
137
What is SOCL2 used for?
convert carboxylic acids into acyl halids
138
What condition do you get monosubstitution of an aromatic ring?
aprotic solvent
139
is crystal formation exothermic or endothermic?
endothermic
140
How do you know which carbon will be attacked by nucleophile?
most substituted, good leaving group
141
What is acetylation?
attachement of R=O
142
What is a gringard reagent?
RMgBr, will alklylnate
143
What happens to absolute configuration when the lowest priority group is facing me?
Have to revserse the configurations
144
What does a dashed line mean in lewis structure?
they are pointing into the paper/ away from you
145
What are two sources of saturation?
rings and multiple bounds
146
How does pH impact nucleophilicity?
increase --\> increase pH to deprotonate and increase negative charge
147
What is the trend of nucleophilicity in periodic table?
Nucleophilicity increases going down due to greater size and polarizability
148
Does a strong nucleophile impact the kinetics or thermodynamics of a rxn?
kinetics
149
What is the difference between L and D configuration?
L is S configuration and D is R. These are the absolute configurations at C5 in sugars
150
How does acidity change down a periodic table?
increases bc increasing radii, more likely to dissociate, also more stable at delocalizing charge
151
How does acidity change with increase Zeef charge?
increases
152
What type of base is ammonia (NH3)?
weak base
153
What is an example of a non-reducing sugar?
sucrose because does not contain a free carbonyl ketone or aldehyde
154
Which has a better leaving group, acyl chloride or acyl iodide?
acyl iodide bc larger and delocalize charge better
155
What is transesterification?
conversion of one ester into another using an alcohol, The –OH acts as a nucleophile and attacks the ester’s carbonyl carbon, replacing the previous R group on the ester with its own
156
What happens when you put an ester in water?
hydrolyze ester and get carboxylic acid and alcohol
157
Are carboxylic acids more acidic than phenols?
yes
158
What are configuarational isomers?
structural isomers and are just bonded in a different way (isopentane, pentane)
159
WHat does a high pKb mean?
a weak base
160
Are tertiary alcohols less or more acidic than primary?
less, bc electron donating
161
Is acetal formation reversible?
yes and can have acid catalyzed to recover aldehyde and ketone
162
How to make an ester?
alcohol and carboxylic acid
163
What can break a cyclic ketal?
acidic conditions
164
What are three examples of polar protic solvents?
ethanol, ammonia, H2O
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