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
What are the results in John’s test for each type of alcohol?
Primary and secondary alcohols- gives positive reaction- orange dichromate ion and greenish blue chromic ion
Tertiary alcohols- do not react
What are the results for the iodoform test?
Ethanol and secondary alcohols- positive test
Tertiary alcohols - no reaction
What is the reagent of the iodoform alcohol test?
Triiodomethane- CHI3
What type of alcohols are carboxylic acids and esters reduced to?
Primary alcohol
What halogens can be used in Grignard reagents?
Cl, Br, or I but not F
If an ester is used in Grignard reagents, what is the resulting alcohol?
Tertiary alcohol
Why do larger-substituted alcohols decrease acidity of alcohols?
Bulky substituents groups prevent water from dissolving alcohols, making a sterically inaccessible alkoxide ions
What kind of alcohol are carboxylic acids reduced to?
Primary alcohols
What Grignard reagents?
These are alkyl-magnesium halides RMgX
What are the reagents used to reduce an aldehyde or ketone?
Sodium borohydride, ethanol and hydronic ion
What are the reagents used to reduce Carboxylic acids and esters
Lithium aluminum hydride, ether and a hydronium ion
What 2 reactants can react with Grignard reactants to form a tertiary alcohol?
Ester and ketone
Want happens when sodium borohydride, ethanol and H3O is added to dicyclohexyl ketone?
Dicyclohexyl ketone is reduced to dicyclohexylmethanol
What catalyze biological oxidation?
Alcohol dehydrogenase
What is the oxydizing of Biological oxidation?
Nicotineamide adenine dinucleotide
What is treatment for ingestion of toxin forming alcohols (ethylene glycol and methanol)
Excess ethanol
What is a catalyst to the Fischer esterification reaction?( alcohol and carboxylic acid)
Sulfuric acid
How can phosphate esters be derived from alcohol?
Addition of an alcohol will be added to phosphoric acid to produce a phosphate ester and water
In William ether synthesis, how can the corresponding alkoxide be formed?
Reaction of an alcohol with an alkali metal or with a strong base such as NaH
What if the alkyl halide in the Williamson ether synthesis reaction was a secondary or tertiary alkyl halide?
The alkoxide will act as a base an an elimination reaction will take place
What are the qualitative tests for alcohols
Jones test
Lucas test
Iodoform test
