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Organic Chemistry > Final Exam Practice > Flashcards

Final Exam Practice Flashcards

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1
Q

What is LDA?

A

lithium diisopropylamide

It is used as a base in reaction to favor an enol in equilibrium and allow for the alkylation of alpha ketones. Often used with THF as solvent.

**Bulky, so wil pull off less crowded alpha hydrogen

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1
Q

What is the result if you treat an ester with NaOet and then H+

A

Claison condensation. Remember R-O is a good leaving group.

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1
Q

what reagant allows you to reduce phNN group?

A

H3PO2

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2
Q

What is true of the reaction rate in allylic, benzylic, and vinyl halides undergoing SN2 reactions?

A

-Vinylic halides do not undergo SN2 reactions (No SN2 on SP2) -Allylic and benzylic halides undergo SN2 much quicker than corresponding simple alkanes

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2
Q

What is important to know about Michael reactions?

A

There are 1,2 additions and 1,4 additions.

A 1,4 addition is also known as a Michael addition or a conjugate addition.

In this situation, the nucleophile attacks the C=C bond and forms a temporary enol that rapidly tautomerizes into a ketone.

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2
Q
A
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2
Q

adding this to phNN

A

phOH

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3
Q

What happens when you have a ketone in basic conditons (OH)?

A

A beta-hydroxy ketone forms. The alpha carbon of one ketone attacks the carbonyl of the other, a tetrahedral intermediate is formed, and the protonated. (Aldol addition)

**You can also go all the way to an alpha,beta unsaturated ketone by reforming the carbonyl (Aldol condensation)

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4
Q

What is the result of adding the following to an amido group?

A

“decarbonyl”

Hofman rearrangement

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4
Q

What reagant allows you to add F to a benzene

A
  1. HNO3/ H2SO4
  2. H2/ Pt
  3. NaNO2/ HCl
  4. HBF4/ heat
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5
Q

Adding this to ph-NN

A

ph-Br or ph-Cl

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6
Q

What is the difference between epoxide opening in acidic and basic conditions?

A

Acidic conditions: epoxide is activated and then the nucleophile attacks the more positive (more substituted side).

Basic conditions: the strong nucleophile attacks the more available side (less substituted)

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7
Q

What are examples of common michael donors?

A

Michael Donors= (nucleophile)

Beta di-ketone

Beta-keto ester

Gilman (R2CuLi)

Beta-keto nitrile

alpha-nitro ketone

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8
Q

What are these reactants responsible for?

A
  1. deprotonate methylene carbon
  2. add Br group
  3. hydrolyze R-O-R and decarboxylate
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9
Q

If you are creating a cyclic acetic acid derivative from a malonic ester, how would you do this?

A
  1. NaOEt/ EtOH
  2. Br-R-Br (two Brs allows a cyclic compound to form at the methylene carbon)
  3. H3O+/ heat to hydrolyze and decarboxylate
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11
Q

adding this to phNN

A

ph-I

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12
Q

Adding the following to a carboxylic acid

A

Alpha-Bromination

Replaces hydrogen with Br in a keto enol reaction

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13
Q

When looking at ethers and figuring out what happens in a reaction, what should I look for specifically?

A

Look for ACETALS!!! Ethers don’t react unless you have lots of heat or a strong acid. Acetals react.

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14
Q

How can you identify if something is a Michael donor?

A

Has two electron withdrawing groups and an active methylene group!

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15
Q
A

POWERFUL ACTIVATOR! No catalyst necessary. Br will add in all ortho/para positions

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16
Q
A
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16
Q

adding this to phNN

A

phF

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17
Q

What is the result of the addition of X2 to a double bond? and why?

A

Anti-addition because of the formation of a halonium ion!

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18
Q

What is the result of you add CN to an alpha beta substituted ketone

A

favors conjugate 1,4 addition!

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19
Q

What do the following reagants do?

A

“de-acid chloride”

turns an acid chloride into an R-NH2. (eliminates 1 Carbon, from the carbonyl)

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21
Q

What is the best way to add an alkene with a 1,4 addition (Michael addition)

A
  1. R2-CuLi (Gilman’s reagant)
  2. H+
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22
Q

In ring opening of epoxides in acidic conditions, how does it attack?

A

The epoxide is protonated and the weak base attacks the most substituted side. The configuration at the reaction site is inverted whereas the OH configuration is retained. Always results in a trans product

22
Q

adding this to phNN

A

phCN

23
Q

In free radical polymerization. What is true of the polymer compared to the monomer?

A

Every atom on the polymer has the same connections as the polymer.

ex: if C1 of the monomer has 2 hydrogens, then C1 of the polymer should have 2 hydrogens.

24
Q

What is the result of adding H3O+ and heat to an ether and acetal?

A

Acetal is more reactive so returns to a carbonyl. The ether doesn’t react in weakly acidic conditions.

26
Q

In order to form a dihalide cyclopropane with CHX3, what intermediate is created, what is the general mechanim?

A

A strong base is ued to deprotonate the CHX3. A halide groups leaves so that you are left with the neutral, carbene (CX2).

A double bond can then attack the carbene to form a cyclopropane.

26
Q

What reagant may be used to reduce amines that wont reduce aldehydes or ketones?

A

NaBH3CN

or Na(CH3COO)3BH

27
Q

How would you determine which compound forms the greatest equilibrium concentration of the enol tautomer?

A

A beta-dicarbonyl!!! Just remember that the proton will be negative more often in this case. Very acidic!

28
Q

What is the following reagant used for?

limitations?

A

alpha bromination

cannot be used on aldehydes (they oxidize to carboxylic acids)

29
Q

How do you determine the change in the rate of reaction of a given equation when you are given a change in solvent concentration?

A

rate=k[A][B]

Figure out the order of the reaction. In the above example, it is first in A and first in B. A change in solvent concentration will dilute the concentration of A and B by an equal amount.

new rate=k[dilutedA][dilutedB]

Based on the amount of dilution, you can find the new rate increase/decrease

30
Q

In alpha bromination and acidic conditions, where does bromination occur?

A

more substituted side

31
Q

If you see an acetone derivative, how was it most likely synthesized?

A

Acetoacetic ester synthesis:

  1. NaOEt
  2. R-Br
  3. H3O+
  4. Heat (180 degrees)
33
Q

If you have a compound with three carbons between the carbonyls, how was it probably synthesized?

A

Michael reaction

33
Q
A

1,4-addition!!!!!!

34
Q

If you see a substituted carboxylic acid, how could it have been synthesized?

A

malonic ester synthesis

  1. NaOet
  2. R-Br
  3. H3O+
  4. Heat
35
Q

What is the roll of the claison condensation?

A

Forms a beta-keto ester from an ester.

Reactants are:

  1. R-O

2 H3O+

37
Q

What are the necessary reagants for the hoffman elimination?

A
  1. CH3I
  2. Ag2O/H2O/ heat
38
Q
A
39
Q

What is the nucleophilicity of halides in polar protic solvents?

A

Anions are solvated by hydrogen bonding. Therefore, larger halides that distribute negative charge are better nucleophiles. I>Br>Cl>F

41
Q

What is the nucleophilicity of halides in polar aprotic solvents? (DMSO, acetone, acetonitrile, DMF)

A

Anions are poorly solvated, therefore nucleophilicity parallels basicitiy. F>Cl>Br>I

43
Q

adding this to phNN

A

ph-H

43
Q

What is the result of adding NH3/ Heat to a carboxylic acid?

A

replace OH with NH2

44
Q

When can you NOT form an enolate

A

in the presence of an acidic proton (like carboxylic acid)

hence why we have malonic ester synthesis

46
Q

What is the result when you add CH3 (2eq) to an ester?

A

You get two groups added and an alcohol. It gets reduced!! You can’t isolate at ketone

47
Q

What is the result of adding H3O+ and heat to CN?

A

hydrolyze into carboxylic acid!

48
Q

When determining the product of an aldol condensation, what should I look for to check my work?

A

an unsaturdated alpha, beta product.

ex: CH=CHCN would be an example. It is conjugated and stabilized.

50
Q

Don’t forget what about LiAlH4 and NaBH4 when reacting them with epoxides (or other systems)…?

A

LiAlH4 and NaBH4 are both strong nucleophiles. Don’t forget they can undergo nucleophilic substitution reactions…

With epoxide reactions, they will attack the least substituted side.

51
Q

What are some examples of michael acceptors?

A

conjugated aldehydes

conjugated ketones

conjugated esters

conjugated amides

conjugated nitriles

nitroethylene

52
Q

In ring opening of epoxides with strong bases, how does it attack?

A

With strong base, it behaves like a regular SN2 and the strong base (ex. R-O-) attacks the least substituted side. It inverts stereochemistry on this side, and stereochemistry on the other side of the OH is retained. Results in a trans product

53
Q

Between ketones and aldehydes, which is more likely to spend time in hydrate form in aqueous solution?

A

Aldehyde carbonyls are more reactive so will spend less time as carbonyls and more time as hydrates.

**conjugation reduces reactivity so conjugated aldehyde is less reactive.

54
Q

What does POCl3 or SOCl2 do when added to an amido?

A

turns the amido group into a cyanide group CN

56
Q

What can you add to this to get R-NH2?

A
58
Q

How do you put F on a benzene?

A

Replace nitrizonium ion with F

Start with NO2:

  1. H2/ Pt (to make NH2)
  2. NaNO2/ HCl (to form nitrizoniumm)
  3. HBF4/ heat (to add F)
59
Q

How do you form nitrisonium ion?

A

NaNO2/ HCl

60
Q

Since NO2 (analine) is a not good with FC acylation. How can you add an acyl group to a benzene with an NO2 group present?

A

acylate the amino group first (with an acid chloride), then it becomes a weak activator

Then, you can do FC or add a group that you want ortho/para.

To unacylate the amino group, add OH and heat.

61
Q

Condensation polymerization

A

Functional groups combine and eliminate water. When doing this problem, just look for BEST answer. doesn’t contain double bonds! And not too many functional groups

62
Q

What reagants allow you to “decarbonyl” an amido group?

A
63
Q

What reagant allows you to take off an acid chloride and carbonyl and replace with an NH2?

A
  1. NaN3
  2. H20/ heat
64
Q

If you see a cyclic ketone with an alpha-beta substituted double bond, what most likely occurred?

A

An intramolecular aldol condensation~

65
Q

Adding the following to an R methyl ether

A

haloform reaction, forms deprotonated carboxylic acid

66
Q
A
67
Q

What is the role of NaBH3CN?

A

it reduces amines but not aldehydes or ketones.

particularly useful for tertiary amines.

Organic Chemistry (8 decks)

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