IB DP Chemistry: SL复习笔记10.1.8 Organic Families - Carboxylic Acids & Esters

Carboxylic Acids & Esters

Carboxylic acids

  • Carboxylic acids is the name given to compounds containing the functional group carboxyl, -COOH
  • The general formula of a carboxylic acid is CnH2n+1COOH which can be shortened to just RCOOH
    • (In some countries the family is  called alkanoic acid)
  • The nomenclature of carboxylic acid follows the pattern alkan + oic acid
  • There is no need to use numbers in the name as the carboxyl group will always be on the number 1 carbon atom

Carboxylic Acids Examples Table

10.1.8-Carboxylic-Acids-Examples-Table-1

Esters

  • Esters are functional group isomers of carboxylic acids and contain the functional group, carboxylate, -COOR
  • The general formula of an ester is usually represented as RCOOR where R can be the same or different on either side of the carboxylate group
  • The nomenclature of esters follows the pattern alkyl + alkanoate
  • The alkyl group in the name is the R group attached to the oxygen

Esters Examples Table

10.1.8-Esters-Examples-Table-1

  • Carboxylic acids and esters contain few similarities in their chemical and physical properties
  • H-bonds are present between carboxylic acid molecules and not between esters, so this affects the melting point, boiling  point and solubility:
    • Smaller chain carboxylic acids are soluble in water and have higher boiling points than expected (e.g. ethanoic acid is 117 oC)
    • Esters are insoluble in water and have lower boiling points than their isomeric carboxylic acids ( e.g. methyl methanoate is 31 oC)

Exam Tip

The C in RCOOR is included in the name of the first R group, so C3H7COOCH3 is methyl butanoate not methyl propanoate.Don't be fooled by the order of the atoms in the linear formula:  CH3OC(O)C3His also an acceptable way to write the formula of methyl butanoate!

 

 

 

 

转载自savemyexams

更多IB课程
翰林国际教育资讯二维码