substituent effect on acidity of carboxylic acid

  • Carboxylic acids are stronger acid than phenol and alcohol

        and weaker than the mineral acids like HCl and H2SO4.

  • Carboxylic acid gives proton  easily and formation carboxylate ion, which is  more stable due to  Resonance. 

Substituent effect on acidity of carboxylic acid:

In case of electron donating groups :

Alkyl groups (hydrocarbons) are inductively electron-donating. In this case, the inductive effects pushes electron density onto the carboxylate anion, producing a destabilizing effect, decreasing the acidity of the carboxylic acid.

20.3 donating inductive effect.svg

In case of electron withdrawing groups 

The Electron withdrawing groups like -CN,-NO2,-SO3,..etc  or electronegative atoms like halogens(F,Cl,Br,I),are inductively electron-withdrawing the electron density onto the carboxylate anion, results the stabilizing of carboxylate ion leads to increasing the acidity of carboxylic acid.

Acidity of different acids

I) HCOOH > CH3COOH

II) F-CH2COOH > Cl CH2COOH > Br CH2COOH > I CH2COOH > CH3COOH

III) CF3COOH > CCl3COOH > CBr3COOH > CI3COOH







Comments

Post a Comment

Popular posts from this blog

MID Exam 02 Chemistry

        Government Degree College Tekkali                    Department of Chemistry  Paper-01 (fundamental Organic Chemistry )                      MID Examination -02                                                          Max. Marks-15 Answer the following Questions 1) What is Markownikoff Rule? Explain the mechanism of prepene with HBr reaction. (10m) 2) Explain Diels -Alder Reaction?(5M)
Read more

methylcyclohexane conformations

Image
  methylcyclohexane conformations: 1) Methylcyclohexane is cyclohexane in which one hydrogen atom is replaced with a methyl group substituent.  2) Methylcyclohexane can adopt two basic chair conformations:  one in which the methyl group is axial, and one in which it is equatorial .  3) The most stable conformation of methylcyclohexane is the  chair conformation in which the methyl group is equatorial. 4) The alternative chair conformation, in which the methyl group is axial, is 7.3 kJ/mol higher in energy.  5) This difference corresponds to a equatorial:axial conformer ratio of 19:1 at  25 °C.
Read more

Baeyer Strain Theory

Image
  Semester-3   Unit-2    Fundamentals of Organic Chemistry Baeyer Strain Theory Adolf von Baeyer (a Nobel prize winner) proposed a theory in 1885 to explain the relative stability of the first few cycloalkane. The theory based on following facts: 1. Cyclo-alkanes are saturated compounds. So, all the carbons should have normal tetrahedral angle of 109 o 28 1 (or 109 o  5 1 ). 2. Any deviation of bond angles from the normal tetrahedral value would, impose a condition of internal strain on the ring called bond angle strain or Beayer strain 3. Higher value of angle strain of cycloalkane shows instability. As instability increases reactivity also increase. 4. If all the rings in cycloalkanes assumed to be planar, the bond angle strain for each ring can be calculated below  . 5. According the above table smaller ring compounds cyclo propane and cyclobutane suffer large distortion and believed to be the cause of grater instability and enhanced r...
Read more