OChem Flashcards
1
Q
what bond is shorter, double or single?
A
double
2
Q
what geometry is this?
A
bent
3
Q
what geometry is this?
A
trigonal planar
4
Q
what is the range of charges for oxidation state?
A
- 4 to +7
- treat bonds as if they are ionic bonds where most electronegative atom will get transferred the electrons
5
Q
how do you calculate bond order?
A
number of bonds/number of attached atoms
6
Q
how do you calculate fractional charge?
A
total charge of attached atoms/number of atoms
7
Q
honc equation?
A
(# of bonds) - (honc #) = formal charge
8
Q
what is this structure?
A
isopropyl
9
Q
what is this structure?
A
sec-butyl
10
Q
what is this structure?
A
tert-butyl
11
Q
what is this structure?
A
iso-butyl
12
Q
CH3COOH
A
acetylaldehyde
13
Q
what is this structure?
A
propanone (acetone!!)
14
Q
what is this structure?
A
acetic acid
15
Q
what is this structure?
A
formic acid
16
Q
what is this structure?
A
benzoic acid
17
Q
what is this structure?
A
salicylic acid
18
Q
what is the suffix for aldehyde?
A
-anal
19
Q
what is the suffix for ketones?
A
- anone
20
Q
what is the suffix for carboxylic acid
A
- anoic acid
21
Q
what is the suffix for esters
A
- anoate
22
Q
what is this structure?
A
methyl acetate
23
Q
EZ system
- when the two higher priority groups on the same side of the double bond, what is it?
A
Z (ze zame zide)
E - when the highest priority groups are on opposite sides of the double bond
24
Q
nomenclature of benzene derivatives:
ortho -
A
(1,2) - beside eachother on benzene ring
25
nomenclature of benzene derivatives:
meta
(1,3) - separated by 1 carbon on benzene ring
26
nomenclature of benzene derivatives:
para
(1,4) - across from eachother on benzene ring
27
what is phenol
a benzene with a hydroxyl group
28
what is benzoic acid
benzene with carboxylic acid attached
29
what is benzaldehyde
benzene with aldehyde attached
30
what is toluene
benzene with methyl group attached
31
what is aniline
benzene group with NH attached
32
what is the order of stability of the conformations of butane? (eclipse, anti... etc.)
anti (methyl groups are 180 degrees apart)
guache (where there is some steric hinderance of methyl groups)
eclipse (where methyl groups are not directly eclipsed ontop of each other)
eclipse (where the two methyl groups are directly eclipsed on each other)
33
34
do enantiomers share the same physical and chemical properities?
they share the same physical properites - except the rotate around polarized light in opposite directions
- they share the same chemical properties unless when reacting with another chiral reagent
35
do diastereoisomers have the same physical/chemical properties?
share similar chemical properties but vary in their physical properties
36
what are meso compounds or meso isomers?
A meso compound or meso isomer is a non-optically active member of a set of stereoisomers, at least two of which are optically active. This means that despite containing two or more stereogenic centers, the molecule is not chiral. A meso compound is "superposable" on its mirror image
37
how are conformational isomers produced?
rotation around a single bond
38
when are two isomers resolvable?
when are isomers interconvertible?
- when there is no small energy barrier separating the two
- when there is a small energy barrier separating the two (such as the conformational isomers of butane)
39
what is chromatography in association with a chiral stationary phase used to separate?
enantiomers
- one enantiomer will move up the plate slower than the other
40
What are the two rules of thumb when dealing with Fischer projections of carbohydrates?
when the hydroxyl group is on the right, what configuration?
left?
when the hydroxyl group is on the right, the configuration is R, and when it is on the left, the configuration is S.
41
what is the equation for specific rotation of enantiomers?
= a(observed)/cxL
c= concentration
l = length of tube in dm
42
what is a single bond, double bond, and triple bond? (σ and pi)
single - sigma
double - sigma and pi
triple - sigma and two pi
43
what is a coordinate covalent bond?
when the two electrons that form the covalent bond come from the same atom (the lewis base - electron donor)
44
smaller the pKa, _____ the acid
stronger (-2 and below is considered strong acid, -2 to 20 considered to be a weak organic acid)
45
what are some functional groups that act as bases? acids?
bases - amines, amides
acids - aldehydes, carboxylic acid, carboxylic derivatives, ketones, alcohols
46
nucleophiles - dependent on 4 things. does nucleophilicity increase or decrease with each?
charge
electronegativity
steric hinderance
solvent (protic vs aprotic polar)
more negative charge, higher nucleophilicity
more electronegative, less nucleophilic
more steric hinderance, less nucleophilic
protic solvents increases nucleophilicity DOWN periodic table (I \> Br \> Cl \> F)
aprotic solvents decrease nucleophilicty UP periodic table (F \> Cl \> Br \> I)
47
heterolytic reactions
opposite of coordinate covalent bonds
- electron pair is given to one of the two products
48
in a nucleophilic substitution reaction (SN1), what is the rate limiting step?
formation of the carbocation, meaning that only the concentration of the substrate determines rate of reaction (not the nucleophile)
rate = k[R-L], where R-L is an alkyl with a leaving group
49
why do SN1 reactions usually end with a racemic mixture?
because of the carbocation intermediate, where the nucleophil can come in at different sides, creating new steriochemistry
50
what is a concerted reaction?
SN2 - bimolecular nucleophilic substitution reaction
- rate limiting step involves two molecules
51
which reaction is preferred for a sterically hindered carbon? which is preferred for a not sterically hindered carbon? why?
sterically hindered - SN1, because the more substituted the carbon is, the more stable the carbocation intermediate is
not - SN2, because it is a front back reaction, where the nucleophile attacks while the leaving group leaves --\> more room for attack means better reaction
52
oxidation vs reduction?
oxidation is increasing the oxidation state of an atom, for example with carbon, you are bonding it to an atom that is more electronegative (usually O, N, F), you are losing electrons
- usually increasing amount of bonds to oxygen
reduction is usually bonding the carbon to a lower electronegative atom such as hydrogen, gain electron
53
common reducing agent? common oxidizing agent?
reducing - LiAlH4 (containing H-)
metals bonded to hydrides
oxidizing - KMnO4, CrO3 (containing O)
metals bonded to oxygens
54
if a molecule like ethanol is in the presence of an STRONG oxidizing agent, what will happen?
will oxidize to carboxylic acid !! will only oxidize to aldehyde if oxidizing agent is in presence of PCC or is a weak oxidizing agent (which will stop the rxn at aldehyde from primary alcohol)
55
is pyridinium chlorochromate a strong or weak oxidizing agent?
is dichromate a strong or weak oxidizing agent?
pyridinium is weak
dichromate is strong
56
what property must the solvent have in nucleophilic/electrophilic rxns?
polar!! like dissolves like!!
- protic or aprotic
57
if two substituents on a benzene ring are 1 carbon apart, what letter is it?
2?
across from eachother?
1 - o
2 - m
across - p
58
what determines the boiling point of alcohols?
the intermolecular H bonding - the more hydroxy groups, the higher the boiling point!
59
acidity of alcohols: put in order of most acidic to least
phenol, i-PrOH, CH3OH
phenol
CH3OH
i-PrOH
60
will substituents that are electron withdrawing decrease or increase acidity of alcohols?
electron donating?
examples of each
withdrawing - resonance structures, like aromatic structures: will increase acidity
donating (alkyl groups)- will decrease acidity
61
what are mesyaltes and tosylates functions?
difference between mesylate and tosylate?
hydroxyl groups are protonated into these to be better leaving groups. also used as protection for alcohols you dont want to react
mesylates- SO3CH4
tosylate - SO3C6H4CH3
62
quinones:
how are they produced?
electrophilic or nucleophilic?
reacting phenols with oxidizing agents
electrophilic because of electron withdrawing groups in the resonance structures of the carbonyl groups
63
what is ubiquinone?
coenzyme Q
64
what does jones oxidation reactions require besides oxidizing agent and solvent?
dilute sulfuric acid
65
acetals and hemiacetal rxns with ketones/aldehydes:
1 equivalent of alcohol will produce what?
2 equivalents of alcohol?
hemiacetal/hemiketal
acetal/ketal AND WATER!!!
- can be reversed in aqueous solution
66
what is a cyanohydrin?
* HCN + aldehyde or ketones
* rxns with aldehydes and ketones will form cyanohydrins once oxygen is reprotonated
67
what kind of rxn is nitrogen/nitrogen-containing derivatives reacting with aldehydes and ketones?
since a small molecule is lost, it is called a **condensation** rxn
* as well as a **nucleophilic substitution** rxn
68
to form a geminal diol, what could you add to attack the carbonyl carbon?
water
69
the electron withdrawing oxygen ________ carbanion (negatively charged carbon)
alkyl groups tend to _______ organic anions
(stabilize or destabilize)
the electron withdrawing oxygen therefore helps stabilize carbanion (negatively charged carbon)
alkyl groups tend to destabilize organic anions
70
electron-withdrawing (or resonance) – like aromatic structures, it will _______ acidity
increase!!!!!
71
how are enols formed?
Enols – formed using a strong base on ketones/aldehydes (OH-, LDA, KH)
72
**Michael addition**? a carbanion attacks an __________ compound
**Michael addition** – a carbanion attacks an a,B-unsaturated carbonyl compound – a molecule with a multiple bond between the a and B carbons next to a carbonyl
73
during formation of enolates from differently substituated ketone a-carbons, there are two different enolates that can form; thermodynamic and kinetic
under what conditions (temperature, reversible/irreversible/strength of base used, rate of rxn) are kinetic enolates formed and what conditions are thermodynamic enolates formed?
where is the double bond formed in kinetic enolates vs thermodynamic?
kinetic enolates – formed in rapid, irreversible, high temperature and strong base reactions
* double bond will form between the carbonyl and a-carbon that is least substituted
thermodynamic enolates – formed in slow, reversible, low temperature, weak base reactions
* double bond will form between the carbonyl and a-carbon that is more substituted
74
aldol condensation - what are the reactants and what is the product?
**aldol ?**
retro-aldol reaction - what are the optimal conditions and what happens in this reaction?
aldol condensation – nucleophilic addition to a carbonyl except the ketone/aldehyde acts as the electrophile and the enol tautomer acts as the nucleophile to form a carbon-carbon bond to form aldol
* after aldol is formed, a dehydration reaction occurs which results in an a,B-unsaturated carbonyl
**aldol** -contains both alcohol and aldehyde functional group
retro-aldol reaction – base is added and heat is applied
* results in the breakage of the a, B-carbon bond
75
