Chemical Forums
Chemistry Forums for Students => Organic Chemistry Forum => Topic started by: rtkt01 on November 18, 2009, 10:29:19 AM
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Outline all steps in the synthesis of each of the following compounds using only the organic starting material given, plus any needed organic/inorganic reagents.
1. 1-bromopropane from 2-bromopropane.
2. 2,3-dimethylbutane from 1-propene.
3. 2-bromo-2-iodopropane from 1-chloropropane.
Here's what I tried.
Zn Br2
1. 2-bromopropane ----> propane ---> 1-bromopropane
H+ light
H2 Br2
2. 1-propene----> propane---> 2-bromopropane
Pt light
2Na
2 2-bromopropane ---> 2,3-dimethylbutane
Boil
Zn I2 Br2
3. 1-chloropropane ---> propane ---> 2-iodopropane ---> 2-bromo-2-iodopropane.
H+ light
It's first time ever I'm solving these types of questions, and I'm really confused with these. Am I on the right track ?
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step 2 in #1 will predominantly give bromination at the 2 position, regenerating starting material. You should think about what ways you know to introduce a halide to a primary carbon, and then how you could form that intermediate from the given starting material
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step 2 in #1 will predominantly give bromination at the 2 position, regenerating starting material. You should think about what ways you know to introduce a halide to a primary carbon, and then how you could form that intermediate from the given starting material
How does this look?
2-bromopropane + KOH ----> propene
propene + HBr (peroxide present) -----> 1-bromopropane
and did I get question 2 and 3 correctly ?
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#2, that would work, soft of. I don't think that was the intended answer for that question though.
#3, like #2, but since that wasn't intended, it now falls off into definitely wrong.
Review your alkene reactions, you probably don't have that many. Do any of them give a halide as a product? Do any of them have a dihalide as a product? A dibromide could be changed into a bromo-iodo compound by stepwise reactions.
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Hmm you must be in my orgchemistry class because I have these exact same questions for hw due tmrw... HCC?
But yeah I got that for #1 and you'll find the answer for #3 on 19A of the practice exam in the back of our notes
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But what about #2?
2,3-dimethylbutane from 1-propene
I've tried hydrogenation to propane followed by addition, but I'm not sure how that extra methyl was added. Does anyone have any suggestions?
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But what about #2?
2,3-dimethylbutane from 1-propene
I've tried hydrogenation to propane followed by addition, but I'm not sure how that extra methyl was added. Does anyone have any suggestions?
I could not get #2 either. I don't know if I'm missing something, but it's just not shown anywhere.
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KOH
1. 2-bromopropane -----> Propene
HBr
Propene -----> 1-bromopropane
ROOR
HBr
2. Propene -------> 2-bromopropane
Li
diethylether l
2-bromopropane + 2 Li ---------> CH3-C-CH3 + LiBr
H
Li
2 l
CH3-C-CH3 + CuI ----------> ( CH3-C-CH3 )2 CuLi + LiI
H
( CH3-C-CH3 )2 CuLi + Cl-CH-CH3 -------> 2,3-dimethylbutane
H l
CH3
KOH Br2 3NaNH2 _ - + NH4Cl
3. 1-chloropropane ----------> H-C=C-CH3 --------> 1,2-dibromopropane -----------> CH3C = C : Na --------->
alcohol CCl4
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CH3C = CH + NH3 + NaCl
_ HBr
CH3C = CH --------> CH3C = CH2
l
Br
HI
CH3C=CH2 --------> 2-bromo-2-iodopropane
l
Br
Can anyone check if there's anything wrong with these?
Thank you.