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Topic: benzene..  (Read 6323 times)

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Offline CHEV

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benzene..
« on: January 24, 2007, 03:52:53 PM »
it's me again... my teacher asked me a question and I've been looking all over the internet trying to fin the answer but i can't find it. i need to know why despite it's toxicity, benzene and aromatic compounds haven't been replaced yet, i mean, why using something that's toxic and cancerogenic instead of something that's harmless?? please someone help meeeee
thanks

Offline FeLiXe

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Re: benzene..
« Reply #1 on: January 24, 2007, 06:29:10 PM »
aromatic by itself isn't toxic. three of the proteineogenic amino acids have aromatic groups. many pharmaceuticals have aromatic groups

in chemical reactions benzene is often replaced by toluene because it is less toxic. but you sometimes need an aromatic solvent, it often works better if you have aromatic substances reacting
Math and alcohol don't mix, so... please, don't drink and derive!

Offline Custos

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Re: benzene..
« Reply #2 on: January 24, 2007, 10:07:08 PM »
it's me again... my teacher asked me a question and I've been looking all over the internet trying to fin the answer but i can't find it. i need to know why despite it's toxicity, benzene and aromatic compounds haven't been replaced yet, i mean, why using something that's toxic and cancerogenic instead of something that's harmless?? please someone help meeeee
thanks
Every chemical is toxic, it's the dose/exposure that matters. Adrien Albert wrote a famous book in 1953 called "Selective Toxicity" on the issue. It's possible to do a reaction in 20,000 L of benzene and with careful control conditions (such that none escapes) be perfectly safe. Chemists work with toxic and carcinogenic chemicals all the time. Working safely is the key.

Offline AhmedEzatAlzawalaty

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Re: benzene..
« Reply #3 on: January 26, 2007, 04:10:14 PM »
it is not replaced becoz it satisfy the chemist needs to synthesize a wide variety of drugs

Offline marcel44

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Re: benzene..
« Reply #4 on: January 31, 2007, 11:20:00 PM »
firstly because it is very cheap, secondly because it has a low bp, third because its a very good azeotrope for water removal, combine with second affirmation, it means that you dont have to boil very high temps (like with toluene) preserving your precious compounds from decomposition, fourth, it has only one peak in 1H nmr and 13C nmr, finally six, even if it is toxic, a good chemist should NEVER die of cancer, it is prohibited.

Offline english

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Re: benzene..
« Reply #5 on: January 31, 2007, 11:28:41 PM »
firstly because it is very cheap, secondly because it has a low bp, third because its a very good azeotrope for water removal, combine with second affirmation, it means that you dont have to boil very high temps (like with toluene) preserving your precious compounds from decomposition, fourth, it has only one peak in 1H nmr and 13C nmr, finally six, even if it is toxic, a good chemist should NEVER die of cancer, it is prohibited.

I don't see how having only one signal means anything. 

Offline marcel44

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Re: benzene..
« Reply #6 on: January 31, 2007, 11:43:38 PM »
how would u use d6 benzene... or u think it is non toxic?

Offline movies

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Re: benzene..
« Reply #7 on: February 01, 2007, 03:42:50 AM »
I don't see how having only one signal means anything. 

It means a lot if you have a complicated spectrum!  Also, using different solvents that have different residual frequencies in the NMR can help to see peaks that are covered by solvent resonances.

Offline english

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Re: benzene..
« Reply #8 on: February 01, 2007, 08:30:28 AM »
I don't see how having only one signal means anything. 

It means a lot if you have a complicated spectrum!  Also, using different solvents that have different residual frequencies in the NMR can help to see peaks that are covered by solvent resonances.

I figured that had something to do with it.  I'm so used to seeing 4 peaks.   ;D

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