Alcohols Flashcards
List 2 methods to synthesize alcohols
Using Grignard reagents
Reduction of carbonyl compounds
What are aldehydes reduced to?
Primary alcohols
What are ketones reduced to?
Secondary alcohols
What is a reagent used to reduce aldehydes and ketone and why?
Sodium borohydride because of it’s safety and use in either water and alcohol
Why do alcohols have higher boiling points than hydrocarbons of similar molecular weight?
Hydroxyl group will make alcohol susceptible to hydrogen bonding, unbounded electrons on the oxygen atom bond with hydrogen on another molecule
What primary alcohols are soluble in water?
Small alcohols, five carbons or fewer.
Why are small alcohols soluble in water?
Small alcohols participate in hydrogen bonding with water molecules
When an alcohol acts as a base, what type of ion does it become?
Oxonium ion
When an alcohol acts as an acid, what is the resulting ion?
Alkoxide ion
What will an increase in alkyl groups of alcohols have on acidity, pka and ka
Acidity decreases, pka increases, ka decreases
Why do substituents reduce alcohol acidity?
Stability of alkoxide ion is affected by solvation effects and electron withdrawing effects
Explain how acidity of alcohols with water is affected by the inductive effect/ electron withdrawal
Electron withdrawal delocalizes alkoxide ion negative charge, spreading it throughout the ion, adding to the ion stability, stabilizing product of deprotonation.( can be done with halide substituents)
Use biological oxidation to explain why methanol is poisonous
Methanol oxidizes to formaldehyde then Formic acid, which is more toxic than methanol
Use biological oxidation to explain what becomes of ethanol
Ethanol oxidizes to acetaldehyde, then acetic acid(a normal metabolite)
What does ethylene glycol oxidize to?
To oxalic acid, which is toxic
Name the reagents and products of an esterification reaction, without acyl chlorides
Reactants: alcohol + carboxylic acid
Catalyst: sulfuric acid
Products: ester + water
Using acyl chlorides, name the reagents and products of esterification
Reagents: alcohol + acid chloride
Product: ester + HCl
Name the reagents and products of Williamson ether synthesis
Reagents: alkoxide ion + primary halide or tosylatec strong base ( like NaH)
Products: ether
Why does William ether synthesis work best with primary alkyl halides?
It is an Sn2 displacement and so facilitates a back-side attack
Name 4 reactions that can be used to convert alcohols into alkyl halides
- Reaction with hydrogen halides
- Reaction with phosphorous halides
- Reaction with Thionel Chloride
- Reaction with tosylate to form tosylate ester
Why are tosylate and mesylates often used to convert alcohols to alkyl halides?
To avoid rearrangements to undesired products on secondary carbons
What are used to prepare Lucas alcohol test?
ZnCl2 in concentrated HCl
What are the results of each type of alcohol in Lucas test
Primary- reacts slowly or not at all
Secondary- reacts in 1-5 minutes
Tertiary- react in less than 1 minute
What are the reagents for John’s alcohol test
Sodium dichromate in acid medium
