Reactions of Ketones And Aldehydes Flashcards
Describe the onolysis of alkenes
O3 and (CH3)2 react with alkynes to form an aldehyde and ketone by oxidatively cleaving the double bond(depending on the Alkene an oxygen is placed on each new double bond)
Explain the mechanism for hydration of alkynes
Markivnikov hydration- terminal alkyne reacts with terminal alkyne. Solution to br used is mercury ions (Hg2+, sulfric acid and water) which forms an Enol intermediate but tautomorizes(relocation of a proton)to its keto form
What is a Gilman reagent?
A lithium dialkylcuprate (R2CuLi)
How can ketone be formed from Gilman reagents?
Gilman reagent reacts with acid chloride
One of the alkyl groups of the Gilman reagent will replace the chloride in the acid chloride to form a ketone, LiCl and R-Cu
NaBH4 can reduce ketones to ____________ _________ and aldehydes to ____________ _________
Secondary alcohols
Primary alcohols
NaBH4 can reduce ketones and aldehydes but not ___________, ______________, ____________ or __________
Esters, carboxylic acids, acyl chlorides or amides
Unlike NaBH4, LiAlH4 can reduce ______ _______ but is …..
Any carbonyl
Difficult to handle
Addition of Grignard reagents to an aldehyde along with a hydronium ion forms….
A secondary alcohol
A ketone reacts with a Grignard reagent and a hydronium ion to form….
A tertiary alcohol
How is an aryl ketone produced?
Benzene reacts with an acid halide (catalyze by a Lewis acid such as AlCl3) to produce an aryl ketone and hydrogen halide
What type of reaction is the preparation of of aryl ketones by fruedel crafts acylation?
Aromatic electric substitution
The addition of Grignard reagents to form alcohols from carbonyl compounds is…,
Irreversible
How can a nitrile be converted to a ketone?
Addition of a Grignard reagents or organolithium to a nitrile which forms an iimine which is hydrolyzed to form a ketone
What is the mechanism for nucleophilic addition reactions under basic conditions?
A negatively charged nucleophile attaches to the carbonyl carbon to form an alkoxide ion intermediate
The alkoxide ion is pronates by added acid Ir solvent to form an alcohol
Explain the mechanism of nucleophilic addition under acidic conditions
the carbonyl oxygen is protonated by an acid to make it more electrophilic
A neutral nucleophile attaches to the electrophilic carbonyl carbon. The oxygen becomes neutral and the nucleophile gains a positive charge
A base deprotonates the intermediate, leaving the alcohol and replenishing the acid catalyst
How can an aldehyde/ketone be converted to an acetal and water?
Addition of an alcohol to an aldehyde/ketone with an acid catalyst
How can aldehydes/ketones be protected?
By converting to acetals
Acetals, like ethers, are _______ to _____, _________ ______ and various nucleophile but can cleaved with treatment with _______
Stable
Bases
Reducing agents
Acids
Describe imine formation using nucleophilic addition of amines
Ammonia or a primary amine is added to ketones/aldehyde with an acid catalyst
Imine and water is formed
Describe how cyanohydrin is formed?
Ketone/aldehyde is reacted with cyanide followed by the proton action of the intermediate and forms a cyanohydrin
What mechanism does the hydration of ketones and aldehydes use?
Nucleophilic addition
What is the wittig reaction?
Converts the carbonyl group into an alkene
How is the Wittig reaction carried out?
Adding a phosphorus ylide to the carbonyl compound
What is a principal advantage of using the wittig reaction over alcohol dehydration for alkene synthesis?
In the wittig reaction has a FIXED double bond for the carbons involved
Describe the mechanism of the wittig reaction
- Phosphorus ylide reacts with the ketone or aldehyde to form a betaine
- The betaine then forms an oxaphosphetane(four membered ring)
- Oxasphosphenate collapses and forms an alkene and triphenylphosphine
Describe catalytic hydrogenation
Addition of hydrogen and ranked nickel
Will attack an alkene first then the carbonyl
What are products formed from each of the tests to distinguish aldehydes from ketones?
Tollens test- carboxylate anion and silver mirror
Feeling/Benedict’s-Carboxylate anion and cuprous oxide
Jones oxidation- Carboxylic acids and chromium ion
