Chapter 26 Flashcards
What is an aldehyde
An aldehyde is a compound with the carbonyl functional group at the end of their chain
How do you name an Aldehyde
Count the carbons to identify the stem
Identify the carbonyl functional group at the end of the chain to the suffix is Al
What is a ketone
Ketones are compounds with the carbonyl functional group in the middle of the carbon chain
How do you name a ketone
Count the carbons to identify the stem
Identify the carbonyl group in the middle of the chain so suffix is -one
Identify which carbon the carbonyl group is on
Do aldehydes and ketones undergo oxidation reactions?
Aldehydes can be oxidised to carboxylic acids when reflux with potassium dichromate and sulfuric acid
Ketones do not undergo oxidation reactions
Are aldehydes and ketones able to undergo nucleophilic addition
Aldehydes and ketones are able to undergo nucleophilic addition due to the polarity of the carbonyl bond due to the electronegativity difference between the carbon and oxygen which induces a dipole
Draw the equation and mechanism for the nucleophilic addition of aldehydes with NaBH4
Aldehydes are reduced to primary alcohols by nabh4
Mechanism in notes
Draw the equation and mechanism of nucleophilic addition of ketones with nabh4
Ketones are reduced to secondary alcohols by nabh4
Mechanism in notes
Draw the nucleophilic addition of aldehydes with hydrogen cyanide
I’ll hides undergo nucleophilic addition with hydrogen cyanide and sulfuric acid to form a hydroxynitrile
Show the nucleophilic addition of ketones with hydrogen cyanide
He tonnes undergo nucleophilic addition with hydrogen cyanide and sulfuric acid to form a hydroxynitrile
Mechanism in notes
How do you test for a carbonyl group
Use a solution of 2 4 dinitrophenylhydrazine
1) add 5 cm of the 2 4 dnp to a test tube
2) add 3 drops of the unknown compound
3) if no crystals form had a few drops of sulfuric acid
4) a yellow / orange precipitate will form which indicates the presence of an aldehyde or ketone
How can you tell whether a compound is either an aldehyde or ketone
4) pour the unknown solution into the prepared tollens reagent
5) leave in a beaker of 50 degrees water for 10-minutes a silver mirror forming indicates an aldehyde
How does tollens reagent work
The aldehydes is further oxidised to carboxylic acid
The silver ions are reduced
How can you identify exactly what aldehyde or ketone is present
1) filter the precipitate formed by 2 4 dnp
2) recrystallized the precipitate
3) measure the melting point of the purified sample and compared to a database
What is a carboxylic acid
A carboxylic acid as a compound that contains a carboxyl group
Are carboxylic acids soluble
Carbusonic acids are soluble due to the polarity of the c o & o h bonds with up to four carbons
As chain length increases solubility decreases due to the non-polar change affecting the overall polarity of the molecule
Dicarboxylic acid dissolve readily due to their two functional groups
Carboxylic acid + metal oxide
–→ salt + water
Carboxylic acid + alkali
→salt + water
Carboxylic acid + carbonate
→ salt + water + carbon dioxide
What is an ester and how can you make them
Draw example
An ester is made by reacting a carboxylic acid and an alcohol creating an ester and water under heat with a concentrated sulfuric acid catalyst
How do you hydrolyse an ester
Draw examples
Acid hydrolysis:
Ester + water→ carboxylic acid + alcohol
Conditions: reflux, dilute aqueous acid
Alkaline hydrolysis:
Ester + sodium hydroxide→carboxylate salt + alcohol
How do you make an ester using an acid anhydride draw example
Acid anhydride + alcohol→ester + carboxylic acid
How do you make an ester from an acyl chloride
Drawer example
Acyl chloride + alcohol/phenol→ ester + HCL
What is an acyl chloride
Acyl chlorides have the functional group CO-Cl
How do you form an acyl chloride
Draw example
Carboxylic acidic acid + socl2→ acyl chloride + SO2 + HCL
What are the three reactions of acyl chlorides
Acyl chloride + water→ carboxylic acid+ HCl
Acyl chloride + ammonia→ primary amide + nh4cl
Acyl chloride + primary amine→ secondary amide + salt
