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Chem 124 > 9/26 > Flashcards

9/26 Flashcards

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1
Q

what does a C=O bond in a carbonyl create? Why is this useful?

A

it creates an electrophilic carbon center that can be attacked by nucleophiles

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2
Q

what is the intermediate that forms when a nucleophile attacks a carbonyl?

A

a tetrahedral intermediate with a alkoxide ion

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3
Q

what are the types of nucleophiles that can attack a carbonyl

A

hydrides and organometallic compounds

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4
Q

what is LAH (lithium aluminum hydride) used for

A

it is a source of hydride, it is an extremely strong reducing agent and can reduce carboxylic acids, esters, ketones, and aldehydes but it is very dangerous and will violently react with water or alcohol solvents (acidic protons)

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5
Q

what is NaBH4 used for (sodium borohydride)

A

it is a source of hydride, it is a weak reducing agent and can only reduce ketones or aldehydes

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6
Q

what type of nucleophiles do organometallic compounds make

A

they make carbanion like nucleophiles

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7
Q

when carbon is bonded to magnesium or lithium what happens to the polarity and reactivity of the carbon

A

the polarity is swapped and the carbon is more negatively charged, this makes it act as a nucleophile with a carbanion like character

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8
Q

what is reduction in organic chemistry

A

it is the increase in hydrogen content and the decrease of oxygen content (a C=O may become C-O, or an oxygen is lost)

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9
Q

What is oxidation in organic chemistry

A

it is the decrease in hydrogen content and the increase in oxygen content (C-O may become O=C, or addition of oxygens)

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10
Q

what can primary alcohols be oxidized to

A

aldehydes and carboxylic acids

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11
Q

what can carboxylic acids and aldehydes be reduced to

A

primary alcohols

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12
Q

what does LAH reduce a ketone to?

A

a 2° Alcohol

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13
Q

what does LAH reduce at carboxylic acid to?

A

a aldehyde and then a 1° Alcohol

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14
Q

what does LAH reduce a aldehyde to?

A

a 1°alcohol

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15
Q

what are the reagents for LAH

A

1.) LAH, Et2O or THF
2) H30 (workup)

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16
Q

why do we need to be cautious when using hydrides as a reagent?

A

in LAH, the hydride can act as a nucleophile and a base, meaning it can undergo violent exothermic acid base chemistry when used in a solvent with an acidic hydrogen (H20 or alcohols)

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17
Q

when using LAH, what solvent should you use?

A

an ether like THF or Diethyl Ether (Et2O)

18
Q

if you wanted to selectively reduce a carbonyl, what reagent should you use

A

NaBH4

19
Q

what are esters reduced to

A

primary alcohols

20
Q

what are the common solvents for a reduction with LAH

A

Tetrahydrofuran (THF), Et2O (diethyl ether), CH2Cl2 (dichloromethane)

21
Q

what is the hardest carbonyl to reduce

A

carboxylic acids

22
Q

whats the easiest carbonyl to reduce

A

aldehyde

23
Q

what should we use if we want a selective reduction of a carbonyl

A

we use NaBH4 which is a weaker reducing agent

24
Q

what is the swern oxidation

A

it synthesizes aldehydes and ketones using DMSO and (COCl)2 and triethyl amine

25
Q

what does PCC do

A

it oxidizes primary alcohols to aldehydes

26
Q

what is reagent for PCC

A

PCC in Ch2Cl2

27
Q

If you react a primary alcohol with KMnO4, OH/ H20 and heat, what do you get

A

a carboxylic acid

28
Q

if you react CrO3 / H2So4 with a primary alcohol, what do you get

A

a carboxylic acid

29
Q

if you react CrO3/ H2SO4 with a secondary alcohol what do you get

A

a ketone

30
Q

what does the jones oxidation do

A

it makes an alcohol into a carboxylic acid or a ketone with CrO3 and H2SO4

31
Q

how is H2CO4 generated

A

in situ with CrO3 and H2SO4

32
Q

what indicates a jones reaction

A

the orange solution turns green after oxidation

33
Q

why are organometallics important

A

they form carbon carbon bonds

34
Q

what is a grinard reagent

A

a Carbon-Mg bond characterized by its carbanion like feature (polarity swap)

35
Q

what do you need to make a grignard reagent

A

an alkyl halide, Magneisum, and Diethyl ether (Et2O)

36
Q

what is an umpolung

A

the reversal of polarity in a chemical reaction

37
Q

what are the reagents for swern oxidation

A

1) DMSO and oxalyl chloride (COCl)2

2) triethyl amine

38
Q

what are the reagents for pyridnium chloro chromate

A

1) PCC in CH2Cl2 solvent

39
Q

when reacting an ester with a grignard reagent, what is the result?

A

you will get a tertiary alcohol

40
Q
A

Chem 124 (29 decks)

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