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Organic Chemistry 2 > Chapter 11- Reactions of Alcohols > Flashcards

Chapter 11- Reactions of Alcohols Flashcards

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1
Q

What is oxidation/ reduction in ochem?

A

Oxidation: gain of O, O2, or X2; loss of H2

Reductuon: gain of H2 or H-, loss of O or O2 or loss of X2

Or Neither

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2
Q

Primary/secondary/tertiary alcohols can be oxidized to what?

A

Primary- aldehyde then carboxylic acid

Secondary- ketones

Tertiary- cannot be oxidized bc no alpha hydrogen on carbon

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3
Q

How do you oxidize primary alcohols to aldehydes/ carboxylic acids?

How do you oxidize secondary alcohols to ketones?

A

Primary:

  • > Aldehydes- PCC, Swern (DMSO), DMP
  • > Carboxylic Acids- Chromic Acid

Secondary:
->ketones- PCC, NaOCl, Swern (DMSO), DMP,

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4
Q

Alcohols are weak nucleophiles and electrophiles. How do we make them strong nu and elec?

A

Convert to alkoxide ion to make it a strong Nu

Protonate hyrdroxyl group (OH) to make it a strong electrophile (H2O)

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5
Q

TsOH does what to alcohols?

A

Converts them to tosylate esters (ROTs) which are excellent leaving groups

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6
Q

Tosylate Reactions can occur through what mechanims?

A

Sn2 or E2

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7
Q

What are the two ways to reduce alcohols to alkanes?

A
  1. Dehydrate with H2SO4 (forms alkene) then add H2, forming the alkane
  2. Make a tosylate (using TsCl/ Pyr) the. Reduce with LiAlH4
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8
Q

What happens when an alcohol is treated with an acid (H+) ?

A

The hydroxyl group is protonated to a good leaving group (H2O), then substitution or elimination can take place

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9
Q

In reaction of alchols with HBri, tertiary and secondary alcohols react via which mechanism? And primary?

A

Tertiary and secondary- Sn1 (carbocation)

Primary- Sn2 (inversion of stereochem)

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10
Q

Why is chloride a weaker nu than bromide?

What is used to promote reaction b/w alcohols and HCl?

A

Because it is small and less polarizable

ZnCl2 is added

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11
Q

In the lucas test, what is the reaction rate for primary, secondary, and tertiary alcohols?

A

1

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12
Q

Primary/ secondary/ tertiary alcohols react with lucas agent via which mechanism?

A

Primary- Sn2 (inversion of stereochem)

Secondary/ Tertiary- Sn1 (carbocation)

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13
Q

What are the limitations of HX reactions?

A

Primary and secondary alcohols give poor yields

Elimination competes with substitution

Rearrangements for carbocations

Limited ability to make alkyl halides

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14
Q

Alcohol react with phosphorous halides to form what? What reagents are used? Which give the best yields?

A

Alkyl halides, PCl3 for alkyl chlorides, PBr3 for alkyl bromides, P and I2 for alkyl iodides (PI3 not stable).
Primary and secondary alcohols give best yields.

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15
Q

The mechanism with PBr3 occurs via which mechanism?

A

Sn2

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16
Q

SOCl2 (thionyl chloride) reacts with alcohols to form what? What else is produced?

A

To form alkyl chloride, gaseous HCl and SO2 are produced as byproducts

17
Q

H2SO4 does what to alcohols? What mechanism doss it react with?

A

Dehydrates alcohols to alkenes via E1, thus 3>2>1 because primary rearrange

18
Q

Vicinal diols undergo two reactions:

A

Pinacol rearrangement- diol converts to ketone using H2SO4 and heat, dehydration reaction

periodic acid cleavage- glycols are oxidatively cleaved by HIO4 to form ketones and aldehydes, useful determining structure of sugars

19
Q

What are the fours 5 esterifications?

A

Fischer- alcohol + carb acid

Tosylate ester

Sulfate esters

Nitrate esters

Phosphate esters

20
Q

What is the catalyst in fischer esterification? Why is this method seldom used to prepare esters?

A

Sulfuric acid, and because it is an equilibrium bw reactants and products

21
Q

What is a better way to esterificate alcohols?

A

Use acid chloride, reaction is exothermic and only has HCl as byproduct

22
Q

What is the besr known nitrate ester? How it formed?

A

Nitroglycerine, results from reaction of glycerol with 3 molecules of nitric acid

23
Q

What are the 7 types of Alcohol Reactions?

A 
Dehydration to Alkenes
Oxidation to aldehye or ketone
Substitution to form alkyl halide
Reduction to alkane
Esterification 
Tosylation
Williamson synthesis of ether

Organic Chemistry 2 (6 decks)

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