Chapter 26 - Carbonyls and Carboxylic Acids Flashcards
Carbonyl compounds, Identifying aldehydes and ketones, Carboxylic acids, Carboxylic acid derivatives.
what is the double bond in the carbonyl and alkene functional group made of?
The double bond in the carbonyl and alkene functional group is made of a σ (sigma) bond and a π bond. the sigma bond is formed by the overlap of orbitals between the C and O atoms. the pie bond is formed by the carbon and oxygen p orbitals.
What is the carbonyl functional group?
the carbonyl group is C=O
what is an aldehyde?
aldehydes have the functional group CHO and a suffix of ‘al’.
H-C=O
what is a ketone?
a ketone ends in the suffix ‘one’ and functional group is CO
looks like this:
C
C=O
C
What is the reaction and conditions for oxidation of aldehydes?
the condition are it must be done In reflux
with a K2Cr2O7 / H2SO4 catalyst
Outline the detection of a carbonyl group using Brady’s reagent?
To detect carbonyl (C=O) compounds…
Add 2,4 DNPH (Brady’s reagent)
AIf a yellow/orange precipitate indicates a carbonyls presence
Which reagent can distinguish between an aldehyde and a ketone?
Tollen’s reagent reacts with an aldehyde only
is the double bond = polar or nonpolar?
1) The C=C ( alkene group) is non polar
2) The C=O (carbonyl group) is polar
How does Tollen’s reagent distinguish between an aldehyde and a ketone?
If an Aldehyde group is present a Silver (Ag) mirror is produced. If no Ketone group is present then no silver mirror is produced.
How does Fehling’s reagent distinguish between an aldehyde and ketone?
If an Aldehyde group is present a Brick red precipitate is formed. If a Ketone group is present it stays blue/no change
what to and how are aldehydes reduced to?
aldehydes are reduced by NaBH4 to secondary alcohols.
what to and how are ketones reduced?
Ketones are reduced by NaBH4, to secondary alcohols
outline the reaction of carbonyl compounds with HCN?
hydrogen cyanide HCN adds across the C=O bond of aldehydes and ketones to form a hydroxynitrile ( containing a -OH and -CN functional groups) HCN is a poisonous gas. HCN is made from sodium cyanide NaCN and sulferic acid H2SO4
outline the reaction mechanism for nucleophilic addition of NaBH4 to carbonyl compounds?
outline the mechanism for a carbonyl compound reacting with NaCN/H+ ?
in this reaction, the nucleophile is the cyanide ion, :CN- ( from the NaCN)
How can acidified potassium dichromate distinguish between aldehydes and ketones?
If an Aldehyde is present solution turns from Orange to green.
If a ketone is present there’s no change to solution.
Why is potassium cyanide used instead of hydrogen cyanide?
It’s safer
how soluble is carboxylic acid?
The C=O and O-H bonds in carboxylic acid are polar allowing it to form hydrogen bonds with water.
1) carboxylic acids are only soluble up to 4 carbon atoms
2) solubility decreases as carbon chain increases because the carbon chain is non polar
how strong are carboxylic acids?
carboxylic acids are weak acids and only partially dissolve in water
RCOOH (aq) = H+ + RCOO-
carboxylic acid + metal = ?
in aqueous solution carboxylic acids react with metals to form a carboxylate salt and hydrogen gas.
e.g 2CH3COOH (aq) + Mg(s) = (CH3COO-)2 Mg2+ + H2 (g)
carboxylic acids + metal oxides =?
carboxylic acids react with metal oxides to form a salt and water.
e.g 2CH3COOH + MgO = (CH3COO-)2Mg2+ + H2O
carboxylic acids + alkalis = ?
carboxylic acids react with alkalis to form a salt and water
e.g CH3COOH + NaOH = CH3COO-Na+ + H2O
carboxylic acid + carbonates = ?
carboxylic acids react with carbonates to form a salt, CO2 and H2O
e.g 2 CH3COOH + Na2CO3 = 2CH3COO-Na+ + CO2 + H2O
Name the four carboxylic acid derivatives
1) Ester
2) Acyl chloride
3) Acid anhydride
4) Amide
