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CHEM 2420- organic chem 2 > Carboxylic Acids > Flashcards

Carboxylic Acids Flashcards

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1
Q

T or F: for nomenclature, carboxylic acids have the highest priority

A

true (they’re woke that way)

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2
Q

what happens to a carb acid in water

A

water deprotonates it, making an equilibrium. H is the electrophile, and a hydronium ion and the conj. base is formed. The conj. base is resonance stabilized

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3
Q

when carb acids get deprotonated by water, is the conjugate base unstable?

A

no, it’s resonance stabilized

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4
Q

how can we manipulate the stability of the acid

A

by changing the R group

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5
Q

addition of electron withdrawing substituents to the acid ___ the acidity

A

INCREASES

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6
Q

how does adding electron withdrawing substituents to the acid increase acidity

A

due to the inductive effect

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7
Q

stronger acids have (stable/unstable) conjugate bases

A

stable, because they have electron withdrawing groups

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8
Q

T or F: carb acids may be protonated by a stronger acid (one with lower pKa)

A

true. The one with the higher pKa acts as a base

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9
Q

how can you form a carb acid from an alcohol

A

oxidize a primary alcohol

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10
Q

when oxidizing a 1o alcohol to form a carb acid, what kind of oxidizing agent do we want to use

A

a strong one

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11
Q

give examples of oxidizing agents we may use to make carb acids from alcohols

A

KMnO4, K2CrO7, Jones

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12
Q

how can we oxidize aldehydes into carb acids

A

by using HNO3

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13
Q

T or F: we can use HNO3 to oxidize any aldehyde into the carb acid

A

false, we cannot use this method if our molecule is sensitive to acids

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14
Q

if we can’t use HNO3 to oxidize an aldehyde into a carb acid, what do we do instead

A

use a Tollen’s test

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15
Q

describe a tollen’s test

A

1) 2Ag(NH2)2OH (basic conditions)
2) [H+] (mild acid wash)
= carb acid from aldehyde

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16
Q

how can we form a carb acid from a nitrile

A

do hydrolysis of nitriles

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17
Q

in what conditions can we do hydrolysis of nitriles

A

acidic or basic

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18
Q

what do the arrows look like in the hydrolysis of nitriles

A

acidic: use [H+]
basic: 1) use [OH-} 2) use [H+]

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19
Q

describe hydrolysis of nitriles

A

it’s protons in water or hydroxide in water. We’re hydrolyzing the nitrogen away

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20
Q

how can we make carb acids from alkyl halides

A

grignard reaction with carbon dioxide

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21
Q

describe how the grignard reaction is used to form carb acids

A

make the grignard reagent forst, then react with with CO2 and THF (solvent), which forms a new C-C bond. Then we do hydrolysis ([H+]) and we have our carb acid

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22
Q

can we use water in the grignard reaction

A

NO. conditions must be anhydrous until the work up

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23
Q

which carbon acts as the nucleophile in the grignard reaction? why

A

the carbon of the alkyl halide is the nucleophile and attacks the CO2 electrophile, because once the Mg was inserted the dipole was reversed

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24
Q

why do we use THF as a solvent in the grignard reaction

A

its polar and aprotic (we don’t want anything protic in this step)

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25
Q

what happens in the reduction of a carb acid

A

it turns into an alcohol (it’s the opposite of how we make them)

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26
Q

how do we do the reduction of carb acids

A

1) LAH
2) [H+]
= primary alcohol

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27
Q

why must we use LAH in the reduction of carb acids

A

NaBH4 is too weak

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28
Q

what do we do if we want to reduce a carb acid to an aldehyde

A

the reduction won’t stop until alcohol is reached, so we make an alcohol, then use PCC to oxidize it to an aldehyde

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29
Q

describe the addition elimination reaction

A

we convert the OH of the carb acid into a better leaving group, then react it with a nucelophile, giving us a carb acid derivative (carbonyl attached to R and Nuc)

30
Q

what happens if the carb acid derivative reacts with water? what is the implication of this

A

hydrolysis converts it back to a carb acid (bad), so we don’t want to add water in this reaction. Instead, use a different nuc

31
Q

T or F: we can convert carb acids to acyl halides in one step

A

false

32
Q

why cant we convert carb acids to acyl halides in one step

A

OH is a bad LG, so we must come up with a better one

33
Q

what are 3 useful reagents to use to make an acyl halide

A

SOCl2, PBr3, PCl5

34
Q

describe the mechanism of acyl halide formation

A

the OH of the acid attacks the reagent (probably SOCl2) which then attaches. A Cl leaves as a carbonyl is formed, then the lone O is deprotonated, and we are left with a good LG

35
Q

in the first step of the mechanism to form acyl halides, what acts as the nucleophile

A

the OH of the carb acid

36
Q

why is the product of the first part of the acyl halide mechanism a good LG

A

it has resonance and the inductive effect when it leaves

37
Q

now that there’s a good LG in the acyl halide mechanism, what happens

A

Cl attacks the molecule, we get electrons moving, LG leaves, and we have an acyl halide

38
Q

other than an acyl halide, what is produced during the mechanism

A

SO2 gas (which is a good driving force of the reaction)

39
Q

how can we form a carb acid from an alkyne

A

1) O2, DCM, -78 degrees
2) An, AcOH

AcOH=acetic acid

produces 2 carb acids

40
Q

what is the product when a C type nucleophile (ie grignard) reacts with an acyl halide

A

a 3o alcohol

41
Q

how many times does a C type nuc attack an acyl halide

A

2

42
Q

what is the product when an H type nucleophile (ie LAH) attacks an acyl halide

A

a 1o alcohol

43
Q

how many times does an H type nuc attack an acyl halide

A

2

44
Q

what is the exception for H type nuc attacking acyl halides twice

A

LTTBA (it attacks only once)

45
Q

what is the product when LTTBA reacts with an acyl halide

A

aldehyde

46
Q

what is the other exception to the twice attack rule on acyl halides

A

cuprates! (they attack once) (ie Me2CuLi)

47
Q

what is the product when cuprates (ie lithium diakyl cuprates) attack acyl halides

A

X is removed, and the alkyl group of the cuprate is added

48
Q

how many times do all other nucleophiles (S, O, N) attack acyl halides

A

only once

49
Q

what is an anhydride

A

basically 2 esters merged together (2 ketones on either side of a lone oxygen)

50
Q

what is the starting reagent for anhydride preparation

A

an acyl halide

51
Q

describe how anhydrides are made from acyl halides

A

we react an acyl halide with a carb acid and a pyridine base (this would happen when we make an acyl halide which then reacts from the acid it came from)

52
Q

in anhydride preparation, what acts as the nucleophile

A

the deprotonated acid (which acts as a good LG)

53
Q

what is the driving force for anhydride reactions (ie why do they proceed)

A

the deprotonated acid is a GOOD leaving group

54
Q

describe the anhydride reaction mechanism

A

anhydride is attacked by the nuc causing electrons to move around, the deprotonated acid LG leaves, and we have two products: a deprotonated acid, and a ketone attached to the nuc

55
Q

what is the term for how esters are made

A

transesterification

56
Q

what are esters made from

A

carboxylic acids

57
Q

how are esters made from carboxylic acids

A

react it with excess ROH and use [H+]

58
Q

how do you convert an ester back into a carb acid

A

hydrolysis (excess H+, or OH- and then H+)

59
Q

when may transesterification be intermolecular

A

when it produces a 5 or 6 membered lactone

60
Q

describe the basics of intramolecular transesterification

A

the OH at the far end of the carb acid reacts with the carbonyl on the other side = cyclizes into an ester

61
Q

what is an amide

A

ketone attached to NR2 (R may be alkyl group or H)

62
Q

are amides difficult or easy to reaction; what is the effect of this

A

difficult to react, so we must use brute force

63
Q

why are amides difficult to react

A

we cannot make them more electrophilic with H+, because if we did the N would grab it before the O, and we would have a good LG which we don’t want

64
Q

what harsh conditions must we use for amide reactions

A

high temperature, catalysts, time

65
Q

what 3 things can we make from amides and what are the names of those reactions

A

hydrolysis=acids
reduction=amines
dehydration=nitriles

66
Q

describe hydrolysis of amides

A
  • produces carboxylic acids
  • can use H2SO4, heat, and wait 3 hours
  • or we can do 1) NaOH with heat 2) [H+]
67
Q

describe reduction of amides

A
  • produces an amine

- use 1) LAH and Et2O 2) [H+]

68
Q

describe dehydration of amides

A
  • produces a nitrile
  • use SOCl2 or P2O5
  • essentially this reaction makes more bonds to the nitrogen
69
Q

how do we convert a nitrile back into an amide

A

use [H3O+]

70
Q

how can we covert an amide into an aldehyde

A

amide –> nitrile via dehydration, and then reduce the nitrile to an aldehyde (using DIBAL and H+)

CHEM 2420- organic chem 2 (10 decks)

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