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Organic Chemistry 2 > Chapter 22 - Carbonyl Alpha Substitution Reactions > Flashcards

Chapter 22 - Carbonyl Alpha Substitution Reactions Flashcards

1
Q

A carbonyl compound with a hydrogen atom on its _____ carbon rapidly equilibrates its corresponding _____ isomer.

A

alpha; enol

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2
Q

Tautomers are isomers that interconvert spontaneously and can occur in _____ or _____ conditions.

A

acidic (H3O+); basic (-OH)

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3
Q

Tautomers are _____ isomers.

A

constitutional

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4
Q

Resonance forms are different representations of a _____ compound.

A

single

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5
Q

Most monocarbonyl compounds exist in their _____ form at equilibrium

A

keto

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6
Q

Keto-enol tautomerism of carbonyl compounds is catalyzed by both _____ and _____.

A

acids; bases

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7
Q

In acidic conditions, the carbonyl oxygen is protonated by an acid giving a _____ with two _____ _____.

A

cation; resonance structures

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8
Q

In acidic conditions, loss of _____ from the _____ position by reaction with base A:- gives the enol tautomer and regenerates HA catalyst.

A

H+; alpha

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9
Q

In basic conditions, base (-OH) removes the acidic _____ hydrogen yielding an _____ ion with two resonance structures.

A

alpha; enolate

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10
Q

An enolate ion is when a ( + / - ) charge is given to the _____ carbon with the loss of alpha hydrogen and its resonating structures when the negative charge goes to the _____ _____.

A

negative; alpha; carbonyl oxygen

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11
Q

Carbonyl compound can act as a(n) _____ and donate one of its alpha hydrogens to a sufficiently strong base yielding a(n) _____ _____.

A

acid; enolate ion

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12
Q

Enols behave as _____ and react with _____.

A

nucleophiles; electrophiles

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13
Q

Enols are more _____-rich and correspondingly more reactive than _____. The alpha carbon is the negative charge and is electron rich.

A

electron; alkenes

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14
Q

It is important that the nucleophile be a good _____ _____, meaning it has electrons it wants to share.

A

Lewis base

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15
Q

Aldehydes and ketones can be halogenated at the alpha positions by reactions with _____, _____, or _____ in _____ solution.

A

Cl2; Br2; I2; acidic

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16
Q

If an aldehyde or ketone is treated with D3O+ the alpha-hydrogens are replaced with deuterium at the same rate as _____.

A

halogenation

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17
Q

Reaction of an aldehyde or ketone with D3O+ or X2 both involve a _____ intermediate.

A

enol

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18
Q

Alpha-bromo ketones can be dehydrobrominated by base treatment (pyridine) to yield _____.

A

alpha,beta-unsaturated ketones (this is just a double bond between the alpha and beta carbons)

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19
Q

Alpha,beta-unsaturated ketones occur with alpha and beta being in the _____ carbon chain.

A

longest

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20
Q

Acids, esters, and amides do not react with _____.

A

Br2

21
Q

Acids, esters, and amides are brominated by a mixture of _____ and _____.

A

Br2; PBr3 (Hell-Volhard-Zelinskii reaction)

22
Q

_____ converts –COOH to –COBr.

A

PBr3

23
Q

LDA is used on _____ carbons to form a(n) _____ ion.

A

alpha; enolate

24
Q

When a hydrogen atom is flanked by two carbonyl groups, its acidity _____.

A

increases

25
Q

When a hydrogen atom is flanked by two carbonyl groups, the negative charge of enolate _____ over both carbonyl groups.

A

delocalizes

26
Q

Is the enolate ion a cation or anion?

A

anion

27
Q

Enolate ions can be looked at either as _____ _____ (C=C–O-) or as _____ _____ (-C–C=O).

A

vinylic alkoxides; alpha-keto carbanions

28
Q

Most of the time, the (vinylic alkoxides / alpha-keto carbanions) react. This is because they yield a carbonyl compound.

A

alpha-keto carbanions

29
Q

Aldehydes and ketones undergo _____ alpha-halogenation. Although, it is seldom used.

A

base-promoted

30
Q

If excess base and halogen are used, a methyl ketone is _____ _____ and then cleaved by base in the haloform reaction.

A

triply halogenated

31
Q

A halogen-stabilized carbanion acts as a _____ group.

A

leaving

32
Q

CHX3 is called _____.

A

haloform

33
Q

CHCl3 is called _____.

A

chloroform

34
Q

CHBr3 is called _____.

A

bromoform

35
Q

CHI3 is called _____.

A

iodoform

36
Q

Alkylation of enolate ions is base-promoted and occurs through a(n) _____ _____ intermediate.

A

enolate ion

37
Q

Enolate alkylation (R–X) is a(n) _____ reaction. The leaving group X can be _____, iodide, _____, or chloride.

A

SN2; tosylate; bromide

38
Q

Enolate alkylation (R–X) is a(n) _____ reaction. The R group should be _____ or methyl and preferably should be _____ or benzylic.

A

SN2; primary; allylic

39
Q

Malonic ester synthesis is for preparing a _____ _____ from an alkyl halide while lengthening the carbon chain by _____ atoms.

A

carboxylic acid; two

40
Q

A malonic ester is when there are two _____ groups on one CH2.

A

carbonyl

41
Q

Malonic ester is easily converted into its enolate ion by reaction with _____ _____ in _____.

A

sodium ethoxide (Na+ -OEt); ethanol (EtOH)

42
Q

The malonic ester derivative hydrolyzes in _____ (and heat) and loses _____ to yield a substituted monoacid.

A

acid; CO2

43
Q

Esters can be hydrolyzed to a(n) _____ under _____ condition.

A

acid; acidic

44
Q

Decarboxylation requires a(n) _____ group _____ atoms away from the –COOH.

A

carbonyl; two

45
Q

1,4-dibromobutane and a malonic ester enolate ion reacts twice with sodium ethoxide and ethanol to form a(n) _____ product.

A

cyclic (this can occur with other compounds like 1,4-dibromobutane to form 3-, 4-, 5-, and 6-membered rings)

46
Q

What does H3O+ / heat do to a –C(CO2Et)2?

A

it turns it into a –COOH + CO2 + 2 EtOH

47
Q

Acetoacetic ester synthesis converts an _____ _____ into a _____ _____ having 3 more carbons.

A

alkyl halide; methyl ketone

48
Q

What does H3O+ / heat do to a –C(CO2Et)?

A

cleaves it into CO2 + EtOH

49
Q

Ketones, esters, and nitriles can all be alkylated using _____ in _____. (It turns the alpha carbon into an anion by attacking an alpha hydrogen.)

A

LDA; THF

Organic Chemistry 2 (4 decks)

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