Carboxylic Acids

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  • Created by: cf
  • Created on: 07-12-16 20:08
What type of acidity does a Carboxylic acid have?
Weak Acid. Carboxylic Acid > Phenol >Water/Alcohol
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When is 0.4% of ethnic acid dissociated into ions?
At 25 degrees c and with a 0.1moldm concentration
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Test for Carboxylic Acids
Add sodium hydrogencarbonate - colourless bubbles of CO2 produced.
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What may alter the acidity of the Carboxylic Acid?
The presence of substituent groups. Eg substitute one H for a Cl in ethnic acid increases the dissociation of the acid x100.
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How are Carboxylic Acids formed?
Oxidation of Primary Alcohols>Ketone>Carboxylic Acid. Using [O] as acidified potassium dichromate.
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What is the colour change for the oxidation of a primary alcohol into a carboxylic acid?
Orange [CrO7-] to Green [Cr3+] (Acidified Potassium Dichromate) Purple [MnO4-] to BROWN/BLACK SLUDGE [manganeese(IV) oxide.
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What should be taken care of when oxidising a primary alcohol?
The aldehyde is more volatile than the Carboxylic Acid, so should not escape from refluxing reaction mixture...to ensure further oxidation happens.
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Can Secondary alcohols be oxidised to carboxylic acids?
No. Secondary alcohols oxidise to ketones.
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How are carboxylic acids reduced?
CA's are relatively sable compounds so need to use powerful reducing agent -LiAlH4. + ETHOXYETHANE (as reacts violently with water)
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Methods of making aromatic carboxylic acids
Oxidising a primary alcohol (using acidified potassium dichromate/potassium manganate) OR oxidise a methyl side chain.
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How to make an aromatic carboxylic acid by oxidising a methyl side chain?
Heat the compound with alkaline potassium manganate (aq). Initial product is the Na/K salt of benzene carboxylic acid. Mixture then acidified. Makes the acid. PRODUCT: brown/black sludge of manganese(VI)oxide+some Benzaldehyde+BENZENECARBOXYLIC ACID
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What is decarboxylation?
Removal of CO2 from a compound
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What happens because CO2 is an acidic oxide?
It reacts with a base- lime soda.
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What is Lime Soda made of?
Calcium Hydroxide (lots) & K/Na Hydroxide (little)
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What are properties of Lime Soda?
Absorbs CO2 & Water and remains SOLID.
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Ca(OH)3 + CO2
CaCO3 + H2O
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How does decarboxylation occur?
The organic acid/its sodium salt is heated with the soda lime. Hydrocarbon that contains one less C atom in the chain that the starting material is produced.
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When is a Ketone produced?
If the Calcium Salt of the acid is heated. Chain length is increased from a derivative of the 2 carbon ethnic acid to a ketone containing 3 C atoms.
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Other cards in this set

Card 2

Front

When is 0.4% of ethnic acid dissociated into ions?

Back

At 25 degrees c and with a 0.1moldm concentration

Card 3

Front

Test for Carboxylic Acids

Back

Preview of the front of card 3

Card 4

Front

What may alter the acidity of the Carboxylic Acid?

Back

Preview of the front of card 4

Card 5

Front

How are Carboxylic Acids formed?

Back

Preview of the front of card 5
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