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Topic: Redox reactions: Preparing Benzoic acid from toluene  (Read 1391 times)

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Offline Win,odd Dhamnekar

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Redox reactions: Preparing Benzoic acid from toluene
« on: January 17, 2021, 01:43:33 AM »
How do you account for the following observations?
(a) Though alkaline potassium permanganate and acidic potassium permanganate both are used as oxidants, yet in the manufacture of benzoic acid from toluene we use alcoholic potassium permanganate as an oxidant. Why? Write a balanced redox equation for the reaction.

Solution:- Toluene can be oxidized to benzoic acid in acidic, basic, neutral media according to following redox equations.
 


In the laboratory, benzoic acid is usually prepared by alkaline KMnO4 oxidation of toluene. However, in industry alcoholic KMnO4 is preferred over acidic or alkaline KMnO4 because of the following reasons:
(i) The cost of adding an acid or the base is avoided because in the neutral medium, the base (OH- ions) are produced in the reaction itself.
(ii) Since reactions occur faster in homogeneous medium than in heterogeneous medium, therefore, alcohol helps in mixing the two reactants, i.e., KMnO4(due to its polar nature) and toluene (because of its being an organic compound).

My doubts or query: In the attached image, 1)how the equation 3 is derived from 1 +2 ?
2) Is equation 1b correctly stated? If not, what is the correct equation? If yes, How?Please explain.
3)How the equation 1c is derived from the addition of 1a and 1b?


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Offline AWK

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Re: Redox reactions: Preparing Benzoic acid from toluene
« Reply #1 on: January 17, 2021, 02:26:34 AM »
1. Where is equation 3?
2. The error is evident
3. Correct the mistake in equation 1b, then there will be no problem.


In the second figure, you use inconsistent numbering. Should be 1a, 1b, 1a + 1b = 1, 2a, 2b, 2a + 2b = 2
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Offline Win,odd Dhamnekar

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Re: Redox reactions: Preparing Benzoic acid from toluene
« Reply #2 on: January 17, 2021, 03:19:34 AM »
1. Where is equation 3?
2. The error is evident
3. Correct the mistake in equation 1b, then there will be no problem.


In the second figure, you use inconsistent numbering. Should be 1a, 1b, 1a + 1b = 1, 2a, 2b, 2a + 2b = 2

1. Equation 3 is in(i) Acidic medium tagged 1+2=3.

2. Would you explain how can i rectify the error?

  In the second image, all the equations Tagging is self-explanatory.
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Offline AWK

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Re: Redox reactions: Preparing Benzoic acid from toluene
« Reply #3 on: January 17, 2021, 03:40:49 AM »
Can you know the difference between toluene and benzoic acid (benzoate ion)?

Your explanation is just a mess - in point 1 (i) you use the numbers 1, 2, 3, and in point 2 (ii) you use the numbers 1a, 1b, 1c.
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Offline Win,odd Dhamnekar

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Re: Redox reactions: Preparing Benzoic acid from toluene
« Reply #4 on: January 17, 2021, 04:30:39 AM »
Can you know the difference between toluene and benzoic acid (benzoate ion)?

Your explanation is just a mess - in point 1 (i) you use the numbers 1, 2, 3, and in point 2 (ii) you use the numbers 1a, 1b, 1c.

Difference between Toluene(C6H5CH3) and benzoic acid(C6H5COOH).

 Benzoic acid is prepared by replacing 2 H⁺ atoms in CH3 molecule of toluene by 2 O-2 atoms.
Any science consists of the following process.
 1) See 2) Hear 3) Smell if needed 4) Taste if needed
5) Think 6) Understand 7) Inference 8) take decision [Believe or disbelieve, useful or useless, healthy or unhealthy, cause or effect, favorable or unfavorable, practical or theoretical, practically possible or practically impossible, true or false or  any other required criteria]

Offline AWK

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Re: Redox reactions: Preparing Benzoic acid from toluene
« Reply #5 on: January 17, 2021, 04:35:42 AM »
now look at the reaction 2.
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Offline Win,odd Dhamnekar

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Re: Redox reactions: Preparing Benzoic acid from toluene
« Reply #6 on: January 17, 2021, 07:20:32 AM »
now look at the reaction 2.

   In (i) Acidic medium, i understood how the equation 3 is derived.
  In (ii) Basic and neutral media also, I don't find any error.

The answer provided is correct in my opinion.
« Last Edit: January 17, 2021, 09:55:45 AM by Win,odd Dhamnekar »
Any science consists of the following process.
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5) Think 6) Understand 7) Inference 8) take decision [Believe or disbelieve, useful or useless, healthy or unhealthy, cause or effect, favorable or unfavorable, practical or theoretical, practically possible or practically impossible, true or false or  any other required criteria]

Offline Win,odd Dhamnekar

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Re: Redox reactions: Preparing Benzoic acid from toluene
« Reply #7 on: January 18, 2021, 06:54:06 PM »
now look at the reaction 2.

Reaction 2 must be [tex] C_6H_5CH_3 (l) + 2H_2O (l) \rightarrow  C_6H_5COOH (s) + 6H^+ (aq) + 6e^- \times 5 [/tex]

 Thanks for pointing out the error in reaction 2.
Any science consists of the following process.
 1) See 2) Hear 3) Smell if needed 4) Taste if needed
5) Think 6) Understand 7) Inference 8) take decision [Believe or disbelieve, useful or useless, healthy or unhealthy, cause or effect, favorable or unfavorable, practical or theoretical, practically possible or practically impossible, true or false or  any other required criteria]

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