chlorination mechanism

1. When methane gets chlorinated by chlorine, does only chloromethane and HCl are formed or dichloromethane, trichloromethane and tetrachloromethane are formed?? Our sir told that also hydrogen and ethane would be formed? How is this, and what is the exact mechanism then???

2. If chlorine attacks ethane, then what are the possible final products?? Can butane, hydrogen and ethene be formed??

P.S. according to our sir they can be formed.

9 Answers

1
greatvishal swami ·

chlorination occur by free radical mechnism whre following steps take place
a) INITIATION STEP
Cl2------->2Cl.
b) PROPAGATION STEPS
CH4+Cl.------------->CH3.+HCl
CH3.+Cl-Cl------->CH3Cl+Cl.............1
c) TERMINATION STEP
CH3.+Cl.----------->CH3Cl
CH3.+CH3.--------->CH3-CH3.........2

FRM 1 & 2 CLEARLY CHLOROMETAHNE & ethane r frmed

bt following steps may also take place

CH3Cl+Cl.----------->CH2Cl2

SO DICHLOromethane is also formed similarly tri & tetra substituted compounds can b obtained

also H.+H.----------->H2

is another possibility but i think H2will b very less

1
greatvishal swami ·

in 2 mny ptoducts can b obtained use above free radical mechanism try to do it urself u will find it very interesting otherwise i m always there :D

1
gagar.iitk ·

all of the above molecules u are saying are the possible product but hydrogen free redical never formed therefore formation of H2 is not possible even if u take a side rxn of disproportionation of alkyl free redical hydrogen free redical never generates

tell me if any intresting thing u got regarding this rxn

11
Sunil Kumar ·

See there are two mechanism of chlorination of methane...
1st one is:-
1a) Cl(free radical) + CH4 → HCl + CH3(free radical)
1b) CH3(free radical) + Cl2 → CH3Cl + Cl(free radical)
and further so on.

another mechanism is :-
2a) Cl(free radical) + CH4 → CH3Cl + H(free radical)
2b) H(free radical) + Cl2 → HCl + Cl(free radical)

1st mechanism yields chloromethane, dichloromethane and so on while 2nd one can yield hydrogen......

But the thing is which reaction is followed.... And it depends on relative rates of the reactions...
the one mechanism followed is the faster one....
1st mechanism predominates hence choromethane, dichloromethane and others are major product while hydrogen is not yielded much......

1
gagar.iitk ·

is there is a possibility of forming hydrogen gas?

11
Sunil Kumar ·

Yes..... There is a possibility of formation of Hydrgen gas....

33
Abhishek Priyam ·

No!!

No Hydrogen formation ...
Nahi to aag lag jaega :P

just joking..

Mechanism is.....

step1 (chain initiation)

Cl2 → 2Cl.

Step 2 (chain prorogation)

Cl.+CH4→ HCl+CH3.
CH3.+Cl2→CH3Cl+Cl.
.......here no H. formation
Step 3 (Chain termination)

2CH3.→CH3CH3
2Cl.→Cl2

11
Sunil Kumar ·

sorry dude... I just read that the 2nd mechanism in which hydrogen formation is possible actually doesn't take place due to energy considerations..........

1
voldy ·

well guys . I've got one doubt , sorry[2] might seem lame , but important I think . just to recollect . many will b knowing yet.

how do you know that the reaction follows FR path ????[12]

formation of ethane.

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