[ORGO]chlorination

[ippie]

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Which product will be formed in abundance through the following halogenation reaction?
(CH3)2CHCH2CH3 + Cl2 ----- hv, 35 degree celcius -----> HCl + ???

A. (CH3)2CClCH2CH3
B. (CH3)2CHCHClCH3
C. (CH3)2CHCH2CH2Cl
D. All of the above

I think answer is D, but the answer key said the answer is A. why?
Br (radical) has selectivity, but Cl doesn't. right?
Then, the answer should be D. Anybody explain???

 

[Dencology]

Cl and I in peroxide or hv works like Markov. but other HX work anti-Mark. so answer to this question is A.

 

[vvvv]

Which product will be formed in abundance through the following halogenation reaction?
(CH3)2CHCH2CH3 + Cl2 ----- hv, 35 degree celcius -----> HCl + ???

A. (CH3)2CClCH2CH3
B. (CH3)2CHCHClCH3
C. (CH3)2CHCH2CH2Cl
D. All of the above

I think answer is D, but the answer key said the answer is A. why?
Br (radical) has selectivity, but Cl doesn't. right?
Then, the answer should be D. Anybody explain???

this is exactly the same question in Organic textbook, and the answer is B. Organic Chemistry, John McMurry 6E. page 323, problem 10.4.

 

[glk2101]

mcmurry says all are formed in different amounts, all relatively the same..thats strange

 

[userah]

mcmurry says all are formed in different amounts, all relatively the same..thats strange

kaplan says the same thing. it says chlorine isn't as selective as bromine so you'll get all kind of products...

 

[enemi]

Which product will be formed in abundance through the following halogenation reaction?
(CH3)2CHCH2CH3 + Cl2 ----- hv, 35 degree celcius -----> HCl + ???

A. (CH3)2CClCH2CH3
B. (CH3)2CHCHClCH3
C. (CH3)2CHCH2CH2Cl
D. All of the above

I think answer is D, but the answer key said the answer is A. why?
Br (radical) has selectivity, but Cl doesn't. right?
Then, the answer should be D. Anybody explain???

Hi There,
I think A is the right answer because if you draw the four possible radicals, you'll easily see that the tertiary radical is the most stable one, leading to product A, due to increased hyperconjugation.

The question is asking for the major product (key word abundance), D is not correct because you would be saying that all products would be produced with equal ratios, which is not the case. =)
I hope this helped, and correct me if I am wrong. =)

 

[vvvv]

Hi There,
I think A is the right answer because if you draw the four possible radicals, you'll easily see that the tertiary radical is the most stable one, leading to product A, due to increased hyperconjugation.

The question is asking for the major product (key word abundance), D is not correct because you would be saying that all products would be produced with equal ratios, which is not the case. =)
I hope this helped, and correct me if I am wrong. =)

Tert radical is the most stable, so it will form fastest. But It doesnot mean this is the most abundance. To calculate the percentage you have to cal the number of hydrogen, and thier activity. tert hydrogen is 5 times as active as primary, sec is 2.5 time as active as primary. then plus all of them and get the percent.

 

[ippie]

right, tertiary is stable, but not in abundance. we caanot say that tertiary radical is major product. then what's answer? Do you agree the answer is D???

 

[doc3232]

Wow, this is one controversial question: I am not even going to try to answer it.
Most substituted can stabalize the radical best, but that is all I will say.

 

[vvvv]

right, tertiary is stable, but not in abundance. we caanot say that tertiary radical is major product. then what's answer? Do you agree the answer is D???

As I said earlier, the answer is B. look up the Mcmurry organic textbook. calculate percentage of all kinds hydrogen and sec hydrogen has the higest percent.