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Organic chem Flashcards

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1
Q

what is another word for carbocation? and what is tis hybrid?

A

carbonium ; sp2

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2
Q

electron withdrawing vs electron donating

A

withdrawing are pulling electrons toward them

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3
Q

do nucleophiles like electrons

A

they have so many electrons that they give electrons away because they want to get closer to the nucleus so carry neg charge to let the e- seekers know

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4
Q

why is an oil bath used for the distillation method

A

helps to keep the constant temp bc oil will not evaporate

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5
Q

what keeps the condenser cool for the distillation

A

the movement of water in and out which is good since distillation undergoes vaporization and condensation

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6
Q

why do u need a vaccum in a distillation?

A

if u have compounds with high bp, u can uses the vacuum to lower the pressure which will hep to chang it to a gas

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7
Q

why is an oil hot bath and an ice bath needed for distillation?

A

so that molecules can go from gas to liquid (vice versa) quickly

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8
Q

what happens to temp during a phase change?

A

its constant

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9
Q

why use fractional distiilation?

A

when u distill again so that u can have an ideal compund purification from compounds with similar boiling points

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10
Q

which layer (organic or aqueous) has a higher density

A

the aqueaous phase (it contains ions and water)

organic layer has neutral compounds

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11
Q

during extractions what happens during the layers

A

u want the aqueous layer to come through to the flask and the organic layer to stay in the funnel.

this is used for separation so it is a purification method

Separate. By compound properties like ionic or nonpolar or by acid or base

So if u want to separate steroid VS nacl u will add ether and the steroid will dissolve in the ether and the more dense (water and ions) will be poured out first so basically polar goes out first because most dense due to water…

If u want a nonpolar, get a polar solvent
So use opp solvents of the desired compound

But for acid and base u will have rxn
The base will react well with acidic solvent and will travel down along with solvent to aqueous rxn to come out

Desired acid will need an a basic solvent

Neutral will stay in ether

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12
Q

what type of acid is a phenol

A

weak

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13
Q

acidity increases with what?

A

the more pos charge, electroneg (depends b/c have to remember atoms that are most acidic are the ones that are closer to the A of the periodic trend) and the bigger the atom

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14
Q

pick the one thatis most acidic

ammonia or ammonium
HI or HCL

A

ammonium

HI

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15
Q

the basic compounds have a what charge ?

A

neg

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16
Q

-log of 10?

A

-1

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17
Q

diff btwn pka and ph calcul

A

pka is log but ph (h+) is -log

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18
Q

order of acidity

A
  1. electroneg (halogens)
  2. carboxylic acids
  3. phenols (weak acid)
  4. carbonyls
  5. carbanions
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19
Q

whats the main diff btwn nucleophiles and elctrophiles

A

electrophiles are hungry for electrons (so carry the pos charges) so then the nucleophiles will be looking to give away electrons to them (they want to feed them) which will help them too because they want to be closer to the nucleus.

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20
Q

what makes better leaving groups

A
  • stabilized molecules
  • resonance
  • halogens
  • water or other neutral compounds
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21
Q

which one is more stable (thermodynamic) … enol or ketol

A

ketol

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22
Q

what does the reagent H2/ Ni do ?

A

it removes the ring strain of ONLY cyclopropane and cyclo butane and makes them a regular non ring alkane

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23
Q

conformational isomer

A

same molecular formula but differ by rotation around a sigma bond

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24
Q

staggered vs gauche

syn vs anti conformers

A

staggered is less crowded and more stable due to electron repulsion

syn is that the big groups are next to each other while anti means that they are across

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25
Q

epitope

A

contains the virus identity but can go overlooked by immune system if it has an envelope

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26
Q

constitutional isomer

A

compounds with the same molecular formula but have atoms connected together differently

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27
Q

conformational isomers

A

compounds with same molec formula but can be a chair newman or fisher projection because they all are arranged differently around the sigma bond (rotations may be different as well)

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28
Q

another key word for enantiomers are

A

racemic

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29
Q

stereoisomerism

A

same meolc formula but differ with spatial arrangement of atoms like r/s config and e/z confog

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30
Q

factors a chirality

A
  • asymmetric carbon

- not superimposable

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31
Q

formula for stereoisomers

A

2^n and n is number of chiral centers

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32
Q

unsaturation formula

A

[2n+2) - x] / 2

x is hydrogens
ignore oxy
halogens are 1
nitrogen = add 1 more carbon AND hydrogen

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33
Q

two things to focus on when r/s config?

A

if it has D (two hydroogens) or T(3 hydrogens) u should base priorty from heaviest to lightest atomic weight

usually it goes by atomic number but halogens and O always gets priority

halogens comes b4 oh group

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34
Q

what has the same physical properties? enantiomers or disastieromers

A

enenatiomers

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35
Q

describe the process of separating enantiomers

A

u have to use resolution to separate the enantiomers into diasteriomers which will give them diff properties like diff boiling points

use chiral probe that associates with the covalent bomds hydrogen bonds or salts

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36
Q

ex of geometric isomers

A

e/z

cis/ trans

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37
Q

ir frequency for sharp and intense carbonyl

A

ketone is 1700

1735-1680

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38
Q

wavenumber incr as what to freq

A

incr

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39
Q

o-h bond ir freq is

A

3650 - 3200

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40
Q

carbon double bond ir freq

A

1680 - 1620

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41
Q

for an nmr the # of sets of peaks tells

A

of nonequiv protons in the molecule

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42
Q

splitting patterns of the peaks tells

A

tells u # of equiv protons

ex: one peak means that all hydrog are equal

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43
Q

Paper chromatography

A

have a mixture and separating its components through polarity

mobile phase (organic solvent  or even h20) liquid
stationary phase (paper) solid

capillary action will cause the dye to travek from sample stop to a higher spot

if separated in more than one spot - more than one component

  • one that travels more is attracted to solvent
  • one that travels less is attracted to the stationary phase like the paper
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44
Q

thin layer chromatography

A

use glass that is made out of silica (polar stationary)

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45
Q

column chromoatog

A

dump more solvent and separate through diff bands that will travel down

More strongly attracted compound will travel slower than the weakly attracted compound

The one that elutes first is the one that does not attract. Well to the stationary phase so it will be mor on the lower bottom of system

Stationary is usually polar silica Or alumina

Agarose is polar used for electrophoresis

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46
Q

size exchange chromatog

A

stationary is beads that have wholes that have the tiny compounds that get stuck in there so the large ones travel faster

47
Q

ion exchange chromatog

A

compounds with same charge will be repelled so to the stationary so they will travel faster but the ones with opp charge will be attracted to the charge so they will travel slowly

separates by charge

48
Q

affinity chromotog

A

very specific interactions like an enzy,me and substrate

usually the binding of the substrate is bound and everything gets washed out

49
Q

high performance/pressure chromotog (hplc)

A

workinh with smaller compounds and more sensitive

50
Q

gas chromatog

A

gas is the mobile phase
stationary is liquid

most volatile (lower bp) travel faster than the higher bp

separates by boiling point

51
Q

gel electrophoresis

A

separates molecules by size
useful for dna neg charge which will travel to pos charge

  1. restriction enzymes to break dna into fragaments
  2. longer dna fragments (more mw) closer to wells while shorter ones are closer to the pos charge (anode)
  3. overall will look like bands and compare the similarity
52
Q

agarose

A

polysaccharide polymer lets dna molecules travel through it with holes that the dna travels into

53
Q

cathode

A

has a neg charge because this is where reduction takes place

54
Q

anode

A

has a pos charge bc this is where oxidation comes

55
Q

dna ladder

A

standard of the base pairs to refer to for the gel electrophoresis

56
Q

agarose vs sds page (polyacrimide)

A

agarose has big pores so used for big dna fragments (larger than 50 base pairs)

sds page is used for smaller thimgs and proteins

57
Q

why do acetals and hemiacetals form

A

bc alcohol is the nucleophile

hemiacetal forms bc of weak nucleophiule and results with one carbon with one oh group and one OR group

acetal has 2 OR groups on same carbon and a good leaving group

58
Q

ex of weak nucleophile

A

carbonyl by itself

59
Q

what happens when the primary amine is the nucleophile

A

primary amine reacted with the carbonyl will make a imine

a primary amine only has 1 carbon attached to the nitrogen

two hydrogens need to be present like in NH2 and an imine will form which is the carbon double bond to the nitrogen

60
Q

what happens when the secondary amine is the nucleophile

A

enamine is enol form of the two carbon with nitrogen attached to molecule as well

Primary secondary etc amines just mean how many carbons r attached to the nitrogen

Ex is secondary amines have 2 carbons attached

61
Q

why are enamines and enols able to become nucleophiles

A

they are not stable forms and have an alpha hydrogen that is reactive and can attack

Enamines have double bond btwn carbon and nitrogen

62
Q

nucleophilic enolate can react with what at what part?

A

can react with ketone or aldehyde and will attack from the enolate carbon but will go back to an aldol

When the enolate of an aldehyde or a ketone reacts at the α-carbon with the carbonyl of another molecule under basic or acidic conditions to obtain β-hydroxy aldehyde or ketone, this reaction is called Aldol Reaction.

Aldol addition has oh and carbonyl groups
Aldol condensation has no oh group bc it loses h20

63
Q

heat elimates what

A

hydrogen and oxygen (water)

64
Q

aldol has what two characteristics

A

alcohol and aldehyde

65
Q

aldol vs retro aldol rxn vs aldol condensation

A

aldol makes bigger products and add things together

retro aldol makes smaller products and retro (maybe aldol too must check!) will break the bond at the alpha carbon of the carbonyl

aldol condensation uses heat to form a product that is an enal (aldehyde and enol) due to base attacking twice

66
Q

saponification

A

use animal fat (base) to get addition, then elimination of the leaving group to get the soap

2 sigma bond to 1 pi bond

Breaking a fat like oil along with a base to form a type of glycerol and soap (sometimes can be a fatty acid or a carbon attached to a double bond oxygen, alkali metal, and another r group

67
Q

trannsesterification

A

without a base you can have another ester instead of the one that u started with

68
Q

true or false

an ester posessing two alpha hydrogens is required for beta ketoester formation to be driven to compeltion

A

true because it causes the base to act more as a base

69
Q

why are oh groups bad for leaving groups?

A

not necessarily bad but the bases can steal the hydrogens because basic instead of an acid that will help the leaving group occur

h20 is a good leaving group

70
Q

the one tghat has the l.g is the nucleophile

A

no

71
Q

where is usually the addition cut when it comes to nucleophile attck

A

alpha beta bond must be cut …

its alpha next to cafrbonyl

72
Q

claisian synthesis

A

The Claisen condensation is a carbon–carbon bond forming reaction that occurs between two esters or one ester and another carbonyl compound in the presence of a strong base, resulting in a β-keto ester or a β-diketone.

basically the oh disparears and rest of molecule reacts with the other one but the product should look VERY SIMILIAR to the reactant, just without the OH group

think of water disapearing

73
Q

whe it comes to polarity of rf what can u tell

A

more polar is more slower and lower rf value

74
Q

most polar groups that usually have small rf values

A

cooh
oh
nh3

75
Q

when it comes to tlc, ether is ??

A

nonpolar so it will interact with polar molecules

76
Q

nonreverse tlc means?

A

use polar coating as normal and the nonpolar will elute first

77
Q

Reverse phase chromatography

A

Non polar coating like organic solvent which will cause the nonpolar to like the coating and want to join it so polar will elute first or travel farther

78
Q

Enol VS enolate

A

Enol is double bonded carbon but with oh and r group attached to that carbon

Enolate double bonded carbon but with o negative and r group attached to that carbon

79
Q

pyranose vs hexose

A

pyranose is a 6 membered ring but can be made of 6 diff atoms like oxygen so like 5 carbons and 1 oxygen

hexose is a d membered carbon sugar

80
Q

main structural formula for ketone and aldehyde

A

ketone is like CO

aldehyde is CHO

81
Q

how do u know the placement of oh and h groups on the fisher to the carbohydrate ring form?

A

downright upLEFTING

ex: everything on left will be up
for glucose, only one OH
 at the third carbon on the left..
but has only one H
 at the third carbon on the roght side
82
Q

tautomerization

A

uses an acid or base to go from keto to enol vice versa

base causes the alpha carbon next to carbonyl to get snatched by carbon to turn into enol form (or enolate form with an carbanion or oxyanion)

if acid, the carbonyl will get the h off f acid

83
Q

alpha vs beta anomer

A

alpha has oh on bottom (fish shape so in the sea)

84
Q

In the base catalyzed reaction, why doesn’t -OH do a nucleophilic attack the carbonyl carbon instead of the alpha hydrogen?

A

The hydrogens on the alpha carbon are more acidic, so OH is more likely to pull off that proton rather than go for a nucleophilic attack on the carbonyl carbon.

85
Q

ethoxide and LDA have what in common?

A

both strong bases

86
Q

why does the kinetic reaction need to take place in a cold environment? I would have assumed the “fast” kinetic product can be formed at room temperature, but the thermodynamic product would need the temperature control.

A

The kinetic product benefits from the colder temperature because it has a lower activation energy and the activation energy of the reverse reaction (products reforming the reactants) is to great for the reverse reaction to proceed. Once the kinetic reaction occurs, which is the faster of the two reactions, the kinetic products won’t be able to reform the reactants and possibly undergo a reaction forming the more stable thermodynamic product. Consequently, more of the reactants will be locked in to the kinetic product.

At higher temperatures the reaction will favor the more stable thermodynamic product because the reverse reaction can occur for the kinetic products and will have a lower activation energy than the reverse reaction for the thermodynamic products. Thus, kinetic products will be more likely to reform the reactants than thermodynamic products.

Consequently, the higher temperatures allow reversal of the reaction and the higher activation energy of the thermodynamic product will produce an even greater activation energy for the reverse reaction if the initial reaction is exothermic. Higher activation energies indicate less favorable reactions so the products are more locked in to the thermodynamic product.

87
Q

What is the function of the enolate

A

It’s an excellent nucleophile. Look up “alpha carbon chemistry” for examples of the various reactions/roles of such nucleophiles (i.e. alkylation, aldol, etc.).

88
Q

Why does hydride from NaH deprotonate the enolate, but hydride from LiAlH4 nucleophilically attack the back of the carbonyl to reduce it to the alcohol?

A

NaH is a strong base so it will deprotonate the carboxylic acid first. This makes the hydride ion lose/ decrease its nucleophilicity. LAH does not have problem with this so it will strongly reduce carboxylic acid and ester to alcohol. NaBH4 cannot reduce carboxylic acid because it is not reactive enough.

89
Q

which sides of mol.ecules do kinetic and thermo attack

A

kinetic is hitting less substituted

thermo will go for more sterically hindered alpha carbon of carbonyl

90
Q

gram equivalent weight of h2so4

A

take the molecular formula and then divide by the number of protrons so in this case will divide by 2

91
Q

neutralization formula

A

acid and a base react to form water and a salt and involves the combination of H+ ions and OH- ions to generate water.

92
Q

combination reaction

A

using both reactants to form a product

93
Q

combustion rxn

A

o2 + gas = > h20 + co2

94
Q

metathesis

A

two hydrocarbons react together to make two new hydrocarbons

95
Q

decomposition

A

one reactant product breaks down into two or more products

96
Q

steric #

A

(number of lone electron pairs on the central atom) + (number of atoms bonded to the central atom)

97
Q

when adding h20 to aldehyde or ketone, what happens?

A

carbon attached to two oh , 1 h, and 1 r group if an aldehyde but would be two r groups of ketone

aka hydrate or germinal diol

98
Q

when adding R-OH to an aldehyde or ketone, what happens?

A

carbon attached to two O-R groups, one R group, one H group if a ketone.
only one oh group if aldehyde

99
Q

common catalysts to form the acetal

A 
usually acidic (not talking about the reagent but the acetal) which could be h+, tluensulfonic acid TsOH R,
H2SO4
100
Q

what is the diff btwn diol and diothiol protection groups

A

diol puts protection group on carbonyl but the diothiol (SH) group protects the carboxylic acid from getting degraded to an oh by LIALH4

101
Q

a secondary amine and a carbonyl reacting makes a what?

A

enamine which is a double bond between two carbons but one of the carbon are attached to a nitrogen

102
Q

Grignard rxn

A

uses organometalics which are polar bonds between a metal and carbon, making the carbin very electroneg. also helps to cause the electroneg carbon to do a nucleophilic attack on the carbonyl

product will not show the metal but rather an oh group and the carbon group of the reactant

R-Li- X or R - Mg - X are the usual reactants that react with the carbonyl

r= carbon and the x= halogen

103
Q

aldehyde + Grignard reactant =

A

have an extra carbon added to the molecule and overall will be a secondary alcohol

104
Q

ketone + Grignard rxn =

A

no extra carbons so same number of carbons and overall molecule will be a tertiary alcohol

105
Q

LiALH4 vs NaBH4 reducing agents

A

nabh4 is weaker nucleophile and can only reduce ketones and aldehydes into alcohols wherease the former can reduce all of them and then some like esters and carboxylic acids

106
Q

tollen’s reagent for oxidizing rxns

A

which is a colorless, basic, aqueous solution containing silver ions coordinated to ammonia [Ag(NH3)2+]. It is prepared using a two-step procedure

ex: turns an aldehyde into an carboxylic acid

107
Q

na2cr2o7, h2so4 vs tollen’s agent ([Ag(NH3)2+].

A

the former can oxidize aldehydes into carboxylic acids and alcohols into carbonyls
but the latter cannot oxidize alcohols

108
Q

na2cr2o7 vs PCC

A

the former can oxidize alcohol into a carboxylic acid whereas the latter can oxidize alcohol to an aldehyde

109
Q

Which of the following does NOT show optical activity?
A. (R)-2-butanol
B. (S)-2-butanol
C. A solution containing 1 M (R)-2-butanol and 2 M (S)-2-butanol
D. A solution containing 2 M (R)-2-butanol and 2 M (S)-2-butanol

A

Correct Answer: D
Explanation:
This is a racemic mixture of 2-butanol because it consists of equimolar amounts of (R)-2-butanol and (S)-2-butanol. The (R)-2-butanol molecule rotates the plane of polarized light in one direction, and the (S)-2-butanol rotates it by the same angle but in the opposite direction; as a result, no net rotation of polarized light is observed.

110
Q

specific rotation

A

alpha = [alpha observed / c(l)]

c = molarity concentration
l = length in deci m
111
Q

Rank the following in order of decreasing leaving group ability: H2O, HO–, Br–, H–

A

Correct Answer: A
Explanation:
Good leaving groups are weak bases, which are the conjugates of strong acids. Leaving groups must also be stable once they leave the molecule. H2O is, by far, the most stable leaving group and will be extremely unreactive once it leaves the molecule through heterolysis. Br– is the conjugate base of HBr; HO– is the conjugate base of water. HBr is a much stronger acid than water, so Br– is a better leaving group than HO–. Finally, hydride (H–) is a very poor leaving group because it is extremely unstable in solution.

112
Q

DiBal

A

reduction of esters to aldehyde

113
Q

PCC

A

converts secondary alcohol to ketone

but not strong to turn primary alcohols or aldehyde into carboxylic acids

weak oxidizing agent

114
Q

Which conversion between carboxylic acid derivatives is NOT possible by nucleophilic reaction?

A

Correct Answer: D
Explanation:
Remember, there is a hierarchy to the reactivity of carboxylic acid derivatives that dictates how reactive they are toward nucleophilic attack. In order from highest to lowest, this is anhydrides > carboxylic acids and esters > amides. In practical terms, this means that derivatives of higher reactivity can form derivatives of lower reactivity but not vice-versa. Nucleophilic attack of an ester cannot result in the corresponding anhydride because anhydrides are more reactive than esters.

MCAT PREP (14 decks)

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