Carbonyl Compounds Flashcards
Why can aldehydes be distinguished from ketones by oxidation tests?
Aldehydes can be oxidized to carboxylic acids or carboxylate ions?
List 3 tests used to distinguish aldehydes from ketones
- Tollen’s Test
- Fehling’s/ Benedict’s test
- Jone’s oxidation test
Describe Jone’s oxidation reagents and products
Reactants: aldehyde + acidic dichromate solution
Products: Carboxylic acid + Chromium (III) cation
Explain the color change in Jone’s oxidation test
- Orange color due to the presence of dichromate anion
2. Green color of products due to Chromium(III) ion
Describe the reagents and products of Fehling’s/ Benedict’s test
Reagents: aldehyde + Copper oxide
Products: carboxylate anion + cuprous oxide
Explain the color change of Fehling test/ Benedict’s test
Blue color of reactants due to the Copper Oxide(CuO)
Red precipitate from reaction is Cuprous oxide(Cu2O)
What are the reactants and products of Tollen’s test?
Reactants: aldehyde + silver oxide in ammonia to yield a silver mirror
Products: carboxylate anion + silver mirror
Give the general formula for esters, amides and acid chlorides
Esters- RCOOR’
Acid chlorides- RCOCl
Amides- RCONH2
How does the C=O compare to the C=C in Allende
C=O bond is stronger, shorter and more polar that C=C
Name the 2 classifications of carbonyl compounds
- Aldehydes and ketones
2. Carboxylic acids and its derivatives
How do the boiling points of aldehydes and ketones compare to alkanes, ethers and alcohols
Higher than alkanes and ethers due to being more polar, but lower than alcohols because they cannot participate in hydrogen bonding
Are smaller aldehydes soluble in water? Why?
Yes, aldehydes and ketones of 5 carbons and under use the doubly bound oxygen to exhibit hydrogen bonding with water
Are acetone and aldehyde miscible in water?
Yes
Why are aldehydes more reactive than ketones?
- ketones have more steric hindrance than aldehydes
- aldehydes have more partial positive charge than ketones on the carbonyl carbon due to the electron donating alkyl groups( the ketone’s two alkyl group vs the one on aldehydes) making ketones more electrophilic come and less reactive
What is often used to oxidize primary alcohols to aldehydes?
Pyridium Chlorochromate?
Name 2 methods of oxidizing secondary alcohols to ketone
- Sodium dichromate in sulfric acid
2. Potassium permanganate
What is the name of the process to obtain an aldehyde and ketone from an alkanes?
Ozonlysis
What are the reagents and products of ozonlysis?
Reactants: alkene
Catalysts: ozone and dimethyl sulfate
Products: Aldehyde and ketones
What are the qualitative test for aldehydes?
Tollens test
Fehlings / Benedict’s test
Jones oxidation
What are the reagents for catalytic hydrogenation and products?
Benzene of alkanes and ketone
Catalyst: hydrogen and raney nickel
Product: phenol
Why are smaller aldehydes and ketones( less than six carbons) soluble. in water?
Lone pair of electrons on carbonyl group can accept a hydrogen bond on from O-H or N-H
Acetone and acetaldehyde are ___________ in water
Miscible
________________ is the most reactive aldehyde
Formaldehyde
Why is formaldehyde the most reactive aldehyde?
Because the aldehyde has no methyl group attached to it
As aldehydes and ketones increase in length and bulkier attached group, what happens?
The positive inductive effect on the carbonyl carbon decreases, making it less reactive
Aldehydes are formed from the ____________ of _________ ________ and ________________ is used to selectively used to do this
Oxidation
Primary alcohols
Pyridiminium Chlorochromate
Ketones are formed from the ____________ of _________ _____________ using one of the 2 solutions…
Oxidation
Secondary alcohols
Sodium dichromate in sulfric acid
Or
Potassium permanganate
