Carboxylic Acid PDF

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Summary

Carboxylic Acid Carbon in from the carbon bonded to the functional group is the α carbon Carboxyl Group  OH group allows for H bonding Solubility  Chains 1-4 carbon atoms in length are soluble  Chains >4 carbon atoms in length are not soluble Physical Properties  Largely exist as dimers  Rel...

Description

Carboxylic Acid Carbon in from the carbon bonded to the functional group is the α carbon Carboxyl Group 

OH group allows for H bonding

Solubility  

Chains 1-4 carbon atoms in length are soluble Chains >4 carbon atoms in length are not soluble

Physical Properties  

Largely exist as dimers Relatively high melting and boiling points

Amphoteric Nature   

Protons can be added to the carbonyl group (difficult) Protons can be removed from the OH group Far more acidic than the alcohol

Carboxylate Ion    

The negative charge becomes delocalised between the 2 oxygen molecules Delocalised π system is stable Craboxylate salts are readily made by treatemet of the acid with the strong base These salts are much more soluble

Variation in Acid Strength    

Higher pka means weaker acid As chain becomes longer pKa increases Alkyl groups have a tendency to push electrons away from themselves and towards the COO therefore the ions are less stable Halide group would pull electrons in the opposite direction

Protonation of Carboxilic Acids  

Lone electron pair on the oxygen can attract protons Difficult process, but important in terms of reactions

Esterification  

Carboxylic acid + alcohol HCl is needed to catalyse the reaction

Naming    

…yl comes from alcohol …anoate come from carboxylic acid Acid hydrolysis Alkaline hydrolysis

Phosphate Esters

Ester + water



Exist in DNA and phospholipids

Ester Condensation      

Forming a carbon-carbon bond Requires the presence of a strong base Base removes α proton Nucleophilic attack by enolate ion to second ester molecule Alkoxy group is eliminated Alkoxy groups removes the proton

Peptide Bond Formation 

Condensation reaction...