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admin
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 Posted: Thu Sep 03, 2009 2:02 pm Post subject: Epoxide nucleophilic addition |
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w-huang36150
Joined: 29 Nov 2006
Posts: 3
PostPosted: 08 May 2007 01:57 pm Post subject: Epoxide nucleophilic addition
| Quote: | | When a nucleophile attacks the epoxide's carbon in a nucleophilic addition, will it attack the more substituted or less substituted carbon first? Thank you! |
admin
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Joined: 08 Dec 2003
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PostPosted: 08 May 2007 04:53 pm Post subject:
| Quote: | I'm not sure which question you are referring to so I will make some general pointers.
To begin with, hydrolysis of an epoxide (with an acid catalyst) generates a glycol. The hydrolysis of epoxides can be considered to be the nucleophilic addition of water to the epoxide under acidic conditions.
As for all organic chem, examine the most charged atoms which are usually the point of action and balance that will the stability of the products. You certainly will not have to memorize more than that for the MCAT. |
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GraemeMatt8033
Joined: 02 Dec 2009
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| Posted: Mon Mar 08, 2010 12:02 am Post subject: |
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wouldnt all of these things depend on whether the substitution taking place was SN1 or SN2, or does epoxide nucleophilic addition always undergo the same type of substitution? Would it more readily undergo SN2 substitution because of the oxygen? Without having any further knowledge of the mechanism I'd assume SN2 would make the most sense.
Good answer with little data going in |
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mcat_premed3832
Joined: 19 Oct 2006
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| Posted: Mon Mar 08, 2010 5:47 am Post subject: |
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| Which question are you referring to? |
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GraemeMatt8033
Joined: 02 Dec 2009
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| Posted: Wed Mar 10, 2010 12:26 am Post subject: |
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| the epoxide question above |
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mcat_premed3832
Joined: 19 Oct 2006
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| Posted: Wed Mar 17, 2010 2:25 am Post subject: |
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I would assume that it is more similar to SN2 than SN1 because the rate of the reaction would depend on the concentration of both compounds (ie. the epoxide would not unravel creating a stable intermediate as you would typically see for a tertiary carbocation).
NB: Though the three-membered ring of an epoxide is approximately an equilateral triangle (bond angles are about 60°, highly strained). The strained ring makes epoxides more reactive than other ethers, especially towards nucleophiles, BUT the strained ring does not lead to SN1 due to the instability of the ionic intermediate. |
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