IGCSE/GCSE/O & A Level/IB/University Student Forum

Qualification => Subject Doubts => GCE AS & A2 Level => Sciences => Topic started by: angell on May 02, 2010, 11:22:24 pm

Title: Chemistry - Organic Chemistry Doubt!
Post by: angell on May 02, 2010, 11:22:24 pm
Could somebody tell me what would be the products of the reactions of the following organic molecules with hot concentrated KMno4:

1) CH3-CH2-CH--C-CH2-CH2-CH3
                        |
                       CH3

2) CH2--C-CH2-CH2-CH3
            |
           CH3

3) CH3-CH--CH3

(-- stands for double bond!)
Title: Re: Chemistry - Organic Chemistry Doubt!
Post by: The SMA on May 03, 2010, 06:33:27 am
Quote from: angell on May 02, 2010, 11:22:24 pm
Could somebody tell me what would be the products of the reactions of the following organic molecules with hot concentrated KMno4:

1) CH3-CH2-CH=C-CH2-CH2-CH3
                        |
                       CH3

2) CH2=C-CH2-CH2-CH3
            |
           CH3

3) CH3-CH=CH3

                 
                           O
                           ||
1) CH3-CH2-CO2H+ C -CH2-CH2-CH3
                           |
                           CH3

2)                        O
                          ||
           CO2+H2O+ C -CH2-CH2-CH3
                           |
                           CH3

 ( || means double bond facing upwards)


not quite sure on no.3 though, need someone to confirm this
Title: Re: Chemistry - Organic Chemistry Doubt!
Post by: Nobody on May 03, 2010, 07:50:08 am
In hot KMnO4 reactions..
CH will convert into COOH (CO2H)
CH2 will convert into CO2
C will convert into C=O (Carbon double bonds with oxygen)

so...

3) i think the question is wrong!
CH3-CH--CH3
In this you are saying that the last C forms 5 bonds!!!
Look at this displayed formula (this is what you are trying to say!)

            H H  H
            |  |  |
        H-C-C=C-H
            |     |
            H    H


IF THE MOLECULE IS

CH3-CH=CH-CH3

THEN...REACTION WITH HOT KMnO4 WILL BE

CH3COOH + CH3COOH

[(=) represents double bond)
Title: Re: Chemistry - Organic Chemistry Doubt!
Post by: Saladin on May 03, 2010, 07:54:06 am
Please give a cope of the exact exam paper to prevent confusion about the question you are asking.
Title: Re: Chemistry - Organic Chemistry Doubt!
Post by: The SMA on May 03, 2010, 08:45:04 am
yes, i see now why its weird when i try no.3
the formula is wrong. The Carbon can Never form 5 bonds.
should have been 4 bonds only.

What Nobody n The Mysterious Dude said are right,
please attach a copy of your question so that it can be solved
Title: Re: Chemistry - Organic Chemistry Doubt!
Post by: angell on May 03, 2010, 07:56:04 pm
WELL this isnt FROM the past papers - its from my teachers head.

Maybe THATS why.

Thank You!! :)
Title: Re: Chemistry - Organic Chemistry Doubt!
Post by: angell on May 03, 2010, 08:07:48 pm
And yes, it was a mistake!

The question is

3) CH3-CH=CH2


Sorry!
Title: Re: Chemistry - Organic Chemistry Doubt!
Post by: Saladin on May 03, 2010, 08:11:48 pm

           OH
            |
3) CH3-CH-CH2
                 |
               OH


Title: Re: Chemistry - Organic Chemistry Doubt!
Post by: angell on May 03, 2010, 08:15:24 pm
I still do not get the third one :(

Can you explain?
Title: Re: Chemistry - Organic Chemistry Doubt!
Post by: The SMA on May 04, 2010, 02:38:15 am
Quote from: The Mysterious Dude on May 03, 2010, 08:11:48 pm
           OH
            |
3) CH3-CH-CH2
                 |
               OH




but...isn't thats what you would get if you used cold,dilute KMnO4?...
not quite sure though..
Title: Re: Chemistry - Organic Chemistry Doubt!
Post by: nid404 on May 04, 2010, 05:11:41 am
yes that with cold KMNO4

this is what you get with hot conc KMNO4

CH3CO2H  (CO2 and water are by products)