Chemical Forums
Chemistry Forums for Students => Organic Chemistry Forum => Topic started by: bonfire09 on April 27, 2012, 10:56:21 AM
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Not sure if this is correct but if not help me correct it. Thanks.
here is the link
http://i1242.photobucket.com/albums/gg538/scribbles31/lab191.jpg
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No, most steps are incomplete and there are some octet rule violations.
Dissolving metal reductions are generally accepted to proceed by a series of single electron transfer (SET) steps. Look up dissolving metal reductions in your textbook for some inspiration and try again.
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its not it in the textbook. We use mcmurry an intro to organic chemistry with bioligical applications. I think its outside the scope of the class. Thats why im struggling with this.
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its not it in the textbook.
Then have a look in the library for some other textbooks. You cannot learn organic chemistry from a single book.
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i looked through wade, bruice, mcmurry, and the internet. i cant figure it out
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There must be descriptions of dissolving metal reductions and (single) electron transfer reductions in those books and there certainly are on the internet. Look up Clemmensen reduction, for example. I know it's not exactly the same reaction, but the principles are similar and can be applied to Sn reduction of nitro groups.
Start by transferring a single electron fro Sn to the nitro group.
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I was reluctant to contribute on this as I found it a difficult problem. Even my search for a mechanism of a Clemmensen reduction gave an ionic (http://pl.wikipedia.org/wiki/Redukcja_Clemmensena) and a single electron transfer-ionic mechanism (http://www.organic-chemistry.org/namedreactions/clemmensen-reduction.shtm), or even an optional mechanism (http://www.adichemistry.com/organic/namedreactions/clemmensen/clemmensen-reduction-1.html). None the less, perhaps a link to an example or additional details would be helpful. I probably would have started with a protonation reaction as the first step. Then an electron transfer seems more plausible to me.
I am biased against single electron transfer reactions and I am always seeking to learn how these mechanisms are proven to be radical reactions. I am not averse to radical reactions. Certainly there are many well known radical reactions. The reactions that I agree with generally have an initiation step and cascade of radical reaction returning to products with even electrons. If tin or zinc needs to transfer two electrons, why should this be a stepwise process?
If lithium can be vaporized to lithium radicals plus some dilithium and if I were to believe that paired electrons are better than unpaired electrons, why wouldn't I also think dilithium is two lithium cations being held together by a shared pair of electrons. Wouldn't this be analogous to hydrogen, two protons being held together by a pair of electrons of opposite spin? (Hence, an initiation step being required to break paired electrons and this is the driving force to return to pairs?) Just asking?
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I thought the tin donated two electrons at a time but i'm not sure. I know my reaction mechanism is wrong so im going to simplify this mechanism. I'll show tin in the mechanism but without it donating the electrons.
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I thought the tin donated two electrons at a time but i'm not sure. I know my reaction mechanism is wrong so im going to simplify this mechanism. I'll show tin in the mechanism but without it donating the electrons.
If it were me, I'd draw it by donating two electrons. You cannot do the reduction without tin donating electrons. But, I'd start with a protonation of the nitro group first. I'd like the look of the mechanism if it occurred from a protonated nitro group. I'm not sure tin reduces nitro groups under basic conditions, but I could be wrong. I think if you write out that step, it should give enough impetus to completing the mechanism, except for the last step. You will need to pay attention to the pKa values at the last step.