Oxidation of Secondary Alcohol

[Margel]

Hi to all. I am a synthetic chemist with a difficult problem. I wanted to oxidize 3-hydroxyglutaronitrile to a ketone. I already tried using the standard Cr2O3/ sulfuric acid method. However, after 9 days at 85 oC I only got some crap and some starting material.

 

I understand that the electron withdrawing groups (2

nitrile groups) are making this oxidation difficult.

 

Anyone? Help please.

 

(I am now investigating this oxidation because SN2 reaction of 1,3-dibromoacetone to 3-ketoglutaronitrile using KCN is very problematic. I tried using diferent solvents such as DMSO, DMF etc. but still no reaction.)

[UC]

Perhaps you could use a different synthesis route altogether. The acid form of the nitrile you want to prepare is easily produced by the action of oleum on citric acid, with the liberation of carbon monoxide. The free acid is not very stable, but there may be a good way to convert it to the amide and dehydrate it without it decomposing. Offhand, I don't know any way to transform esters directly into amides, but a link on that page also provides a high-yielding way to make the diester.

 

http://www.orgsyn.org/orgsyn/orgsyn/prepContent.asp?prep=cv1p0010

 

I hope you meant CrO3 and not Cr2O3, since the latter would do absolutely nothing to oxidize a secondary alcohol.

Edited May 21, 2009 by UC

[Margel]

Thank you UC for your reply. What I really mean is CrO3. Sorry for the mistake. This is a problem which I need to be solved as soon as possible as this will be used as a starting material.

 

I cannot think of any other shorter route to the ketoglutaronitrile. So I guess I could try making the acid first then convert to amide then dehydrate.

 

I still wish there is an easier way to prepare this compound. I also cannot believe that this compound has only 1 entry in scifinder and that paper did not even have a procedure or characterization data.

[chemist]

Hi to all. I am a synthetic chemist with a difficult problem. I wanted to oxidize 3-hydroxyglutaronitrile to a ketone. I already tried using the standard Cr2O3/ sulfuric acid method. However, after 9 days at 85 oC I only got some crap and some starting material.

 

I understand that the electron withdrawing groups (2

nitrile groups) are making this oxidation difficult.

 

Anyone? Help please.

 

(I am now investigating this oxidation because SN2 reaction of 1,3-dibromoacetone to 3-ketoglutaronitrile using KCN is very problematic. I tried using diferent solvents such as DMSO, DMF etc. but still no reaction.)

 

Hello,

 

have you tried (COCL2)2, DMS0 with Et3N at -78c?

See: Jones,T.K; Reamer, R.A; Desmons et al J. AM. Chem Soc. 1990, 112, 2998-3017

 

Also check into:

DMSO, EDC in TFA, pyr

 

Hanessian, S; Lavallee, P. Can. J. Chem 1981, 59, 870-877

 

There is also the Dess-Martin Periodinane (DMP) that I use often...

here are some good references for that

 

- J. Am. Chem. Soc. 1983,48, 4155-4156

- J. Org. Synth. 1999, 77, 141-152

- J. Chem. Eng. News 1990, july 16, 3

 

*also note that DMP and precurser IBX can be sensitive to heat and shock so make sure you take care when dealing with these and look up an appropriate procedure on scifinder...

 

- I haven't ever used any of these on your exact substrate before but let me know if neither seems useful after you scan the papers. We have a prof here that specializes in similar chemistry and I can ask him if he knows any specific procedures pertinent to your case.

 

Good luck.. hope this helps...

 

EDIT: I also just remember another good reference for use of DMP check out Evans, D.A.; et al J. Am. Chem. Soc. 1990, 112, 7001-7031

DMP in CH2Cl2, pyr was used pretty successfully in late stages of cytovaricin synthesis...

[Margel]

Chemist,

 

I really appreciate your reply. But perhaps I did not explain everything clearly. CrO3/H2SO4 is already a strong oxidizing agent. My substrate 3-hydroxyglutaronitrile did not even show a small sign that oxidation is occuring using this reagent (based on NMR, mostly S.M.).

 

Both Swern and Dess Martin I believe are weaker oxidizing agents and therefore I don't think they will produce better results.

 

I am now wondering if a super oxidizing agent exists ?

[chemist]

Chemist,

 

I really appreciate your reply. But perhaps I did not explain everything clearly. CrO3/H2SO4 is already a strong oxidizing agent. My substrate 3-hydroxyglutaronitrile did not even show a small sign that oxidation is occuring using this reagent (based on NMR, mostly S.M.).

 

Both Swern and Dess Martin I believe are weaker oxidizing agents and therefore I don't think they will produce better results.

 

I am now wondering if a super oxidizing agent exists ?

 

Hello,

 

I know that is a strong oxidizing agent but I think that might be part of your problem... CrO3 isn't exactly functional group compatible... and I've had solubility issues when using it that have led to no reaction...

 

I suggested the others because they are pretty versatile and functional group compatible..... they are also pretty strong.... I've used them on neopentyl alcohols before with good results....

 

Also...

Are you getting back 100% of your starting material?

It might be hydrolyzing your cyano groups.. how are you doing your workup? If you're using water you may be loosing the material that is being hyrdolyzed into the aqueous layer... and cro3 is weird so you typically need waaaay more equivalents then you'd think to get it to work in addition to it destroying your stuff... you might have unreacted S.M. because you're not adding enough equivalents....

 

If you're certain you're not hydrolyzing then you could try calcium or sodium hypochlorite or Cl gas and acid... Also there is oxone.. but I would make double sure you're not hydrolyzing first...

 

Those last few oxidation methods are pretty brutal... let me know if you need some references... if you do decide to try the cl gas you'll want to get a cylinder of it and you'll need special lines, a regulator etc....

 

good luck..

hope this helps.

[UC]

if you do the cl gas you'll want to get a cylinder of it and you'll need special lines a regulator etc....

 

If you have some decent glassware around, you should be able to construct a chlorine generator. You won't have high pressure available, but it's significantly less wait time, hazard, and cost than ordering a lecture bottle. Ideally, you have a pressure equalizing addition funnel charged with hydrochloric acid dripping into a 2-neck flask charged with trichloroisocyanuric acid (swimming pool chemical), calcium hypochlorite, N-chlorosuccinimide, KMnO4, MnO2, etc. The gas is lead through a CaCl2 drying tube before being used.

 

A good writeup can be found here: http://www.sciencemadness.org/talk/viewthread.php?tid=9713

[chemist]

If you have some decent glassware around, you should be able to construct a chlorine generator. You won't have high pressure available, but it's significantly less wait time, hazard, and cost than ordering a lecture bottle. Ideally, you have a pressure equalizing addition funnel charged with hydrochloric acid dripping into a 2-neck flask charged with trichloroisocyanuric acid (swimming pool chemical), calcium hypochlorite, N-chlorosuccinimide, KMnO4, MnO2, etc. The gas is lead through a CaCl2 drying tube before being used.

 

A good writeup can be found here: http://www.sciencemadness.org/talk/viewthread.php?tid=9713

 

Actually this is incorrect for the oxidation procedure I'm quoting he WILL need the cl gas cylinder and special lines or the oxidation will not work predictably...

 

If he is going to generate his own cl gas he may as well just use the bleach... that will likely give the same results.. but if he wants a "super oxidizer" he will want to use the cl gas procedure with the cylinder and a good functioning schlenk line... multiple system purges will be required before use etc...

 

yes this is time consuming but sometimes these specialized reactions are and that's just the way it is...

 

There should be no hazard involved for a trained chemist... Especially if he/she has access to a glove box etc...

 

Although I personally would double and triple check to see if there is any hydrolysis taking place first as h2so4 and water is commonly used to hydrolyze cyano groups and the Cr03 procedure would have a lot of both floating around, he added heat, and left it for days.. seems like a likely possibility to me and something worth looking into before moving forward if he hasn't already...

 

hope this helps...

Good luck.. : )

[UC]

I am familiar with schlenk lines, but with nitrogen instead of chlorine. Do you use a bubbler, and if so, what of? (mercury isn't chlorine-proof )

 

So, we have a dry, oxygen-free, nitrogen-free atmosphere of chlorine over 3-hydroxyglutaronitrile. What reaction (mechanism) takes place? (if you have a ref on hand, I'd be happy to read it over)

 

As for safety, I more meant that the lab in question may never have a need for a lecture bottle of chlorine again, and if it ends up in storage for years, corrosion can be an issue. Granted, under ideal conditions, this would not be an issue, but who knows what to expect.

 

As for hydrolysis of the cyano groups, were this occuring, the product would probably not be stable, especially in acidic, oxidizing conditions. See the orgsyn link in an earlier post, which claims total decomposition in a few hours in solution for acetone dicarboxylic acid. I suspect that 3-hydroxypentanedioic acid would not be much better off, especially if there is oxidant around.

 

Personally, I would try the DMP as the next logical step. If that fails entirely, then maybe try something drastic.

Edited May 26, 2009 by UC

[chemist]

I am familiar with schlenk lines, but with nitrogen instead of chlorine. Do you use a bubbler, and if so, what of? (mercury isn't chlorine-proof )

 

Again... I'm not sure if you know what you're talking about.. that is what the regulator is for.. if you do this right the chlorine gas cylinder will come with it's own indication system...

 

Furthermore: most bubblers are mineral oil - not mercury (think density here) - and you simply remove them from the system when doing something corrosive.. there are other ways to tell if you're getting gas through system - i.e. specialized gauges - http://www.ilpi.com/inorganic/glassware/vacline.html - search key word electronic gauge....

 

Not to mention you can run plenty of things through a schlenk line.. we use argon for example.... Nitrogen isn't commonly used in labs anymore.. Argon is preferred because it has a slower escape velocity... so again I'm not sure you know what you're talking about.. cos if I was to make an assumption about a synthesis lab I would assume that their inert atmosphere was Argon...

 

So, we have a dry, oxygen-free, nitrogen-free atmosphere of chlorine over 3-hydroxyglutaronitrile. What reaction (mechanism) takes place? (if you have a ref on hand, I'd be happy to read it over)

 

As for safety, I more meant that the lab in question may never have a need for a lecture bottle of chlorine again, and if it ends up in storage for years, corrosion can be an issue. Granted, under ideal conditions, this would not be an issue, but who knows what to expect.

 

Funny you're able to assume all of that without ever reading the paper... I thought you didn't have SciFinder.. if now you do then simply research oxidations with molecular chlorine and you'll find plenty of references for this procedure...

 

In regards to the disposal of the cylinder.. I don't know how your chem stores works but here if you order a cylinder they deliver it with all of the required equipment.. then take it back and store it in chem stores for the next person to use.. i.e. these things can be shared department wide...

so in a science department this isn't much of a problem... so again I'm not sure you know exactly what you're talking about...

 

As for hydrolysis of the cyano groups, were this occuring, the product would probably not be stable, especially in acidic, oxidizing conditions. See the orgsyn link in an earlier post, which claims total decomposition in a few hours in solution. I suspect that 3-hydroxypentanedioic acid would not be much better off, especially if there is oxidant around.

 

Well just because it's not stable doesn't mean he isn't getting the hydrolyzed product.. that is why it is important to know if he is getting back 100% yield of his S.M.

Neither are the desired product but if he wants to trouble shoot this reaction he'll need to know for certain that he is getting back 100% or really close yield of his starting material and if not then where is it going...

 

just because he sees starting material by NMR doesn't mean that he has 100% of the starting material back.. there is a huge difference between these two things... so again I'm not entirely sure that you know what you're talking about...

 

so like I said before.. if he hasn't already.. he should check for hydrolysis... by first verifying what yield of S.M. he is getting back... if he has done that already and it's 100% yield or really damn close of S.M. then he has to try a different oxidizer if he is unwilling to change the synthetic route...

 

Personally, I would try the DMP as the next logical step. If that fails entirely, then maybe try something drastic.

funny I thought I had already mentioned that...

[Margel]

Wow, thank you all for your replies. Certainly, I got some cool ideas from your input.

 

Based on NMR, there is really no sign that hydrolysis is occurring. There is at least 95% S.M. . The reaction is monitored every few hours then everyday. (Remember that ester hydrolysis in acid is slow, how much more a nitrile which is even more resistant to hydrolysis than an amide).

 

Also sodium hypochlorite or chlorine are weaker oxidizing agents compared to chromic acid i.e. according to my supervisor. He can only suggest KMnO4.

 

Having 2 electron withdrawing groups on my substrate really makes this oxidation hard. Also I do not have problems of functional group compatibility with CrO3 neither solubility problems. My problem is its reactivity.

 

As for the number of equivalents of CrO3, I already added a lot of excess CrO3/ H2SO4. Most procedures actually used 1.1 eq.

 

So far, I have not gotten a very helpful information yet.

[chemist]

Wow, thank you all for your replies. Certainly, I got some cool ideas from your input.

 

Based on NMR, there is really no sign that hydrolysis is occurring. There is at least 95% S.M. . The reaction is monitored every few hours then everyday. (Remember that ester hydrolysis in acid is slow, how much more a nitrile which is even more resistant to hydrolysis than an amide).

 

Also sodium hypochlorite or chlorine are weaker oxidizing agents compared to chromic acid i.e. according to my supervisor. He can only suggest KMnO4.

 

Having 2 electron withdrawing groups on my substrate really makes this oxidation hard. Also I do not have problems of functional group compatibility with CrO3 neither solubility problems. My problem is its reactivity.

 

As for the number of equivalents of CrO3, I already added a lot of excess CrO3/ H2SO4. Most procedures actually used 1.1 eq.

 

So far, I have not gotten a very helpful information yet.

 

Wow to never have any problems with CrO3 you must really work with simple molecules.. It's quite common knowledge around here that CrO3 will eat your stuff and typically does require waaay more than 1.1 equivs for complex molecules and also has solubility issues etc... - see Carey and Sundbergy 4th ed page 748 approximately the 2nd to last paragraph down - for all the info you want on why Cr(VI) reagents can be problematic for complex molecules...

 

if you're certain that you're not hydrolyzing and you don't want to change the synthetic route and you don't like any of the oxidations methods suggested you might just ask your boss how to do it... or crack open C&S part B flip to oxidations and start trying at random...

 

Typically I've found that when problems occur with oxidations one reagent can be considered stronger than the other depending on the conditions.. In your case you're using Cr(VI) reagent which is a transition metal... Nitriles are a common common ligand for those.. so chelation, pi-back bonding etc can be all be things you have to consider when you're using a reagent that has a transition metal.. - see link: http://pubs.acs.org/doi/abs/10.1021/ja01000a024 - if you've got coordination that can be slowing the reaction progress and making the reagent less effective... this is part of the reason why some of these Cr based oxidizers don't work so great in complex molecules or molecules with functionality....

 

but I'd ask your boss if you're already talking to him and you're not finding outside help useful... just ask him...

 

Edit: I wrote a bunch of other stuff that I deleted as everything I was saying in the longer post above is easily verified by the links and references listed below..

 

good luck.

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Wow, thank you all for your replies. Certainly, I got some cool ideas from your input.

 

Based on NMR, there is really no sign that hydrolysis is occurring. There is at least 95% S.M. . The reaction is monitored every few hours then everyday. (Remember that ester hydrolysis in acid is slow, how much more a nitrile which is even more resistant to hydrolysis than an amide).

 

Also sodium hypochlorite or chlorine are weaker oxidizing agents compared to chromic acid i.e. according to my supervisor. He can only suggest KMnO4.

 

Having 2 electron withdrawing groups on my substrate really makes this oxidation hard. Also I do not have problems of functional group compatibility with CrO3 neither solubility problems. My problem is its reactivity.

 

As for the number of equivalents of CrO3, I already added a lot of excess CrO3/ H2SO4. Most procedures actually used 1.1 eq.

 

So far, I have not gotten a very helpful information yet.

 

Oh and by the way... if you check Carey and Sundberg 4th ed part B page 751.. oh I'd say about the 1st paragraph down you'll find this sentence....

 

"KMnO4 is another powerful transition-metal oxidant has found relatively little aplication in the oxidation of alcohols to ketones and aldehydes. The reagent is less selective than Cr(VI), and overoxidation is a problem."

 

You can read the rest for yourself...

but you might want to run it by your boss because I think he might be confused....

Oxidizing reagents are NOT one size fits all...

 

and you and your boss might also want to check out this article: http://en.wikipedia.org/wiki/Nitrile - and search keyword reactions of nitriles....

- pay special attention to the sentence that says "The hydrolysis of nitriles is generally considered to be one of the best methods for the preparation of carboxylic acids." - then just to solidify it I'd do a quick SciFinder search and pull up the experimentals for these hydrolysis reactions and you'll see that this is pretty common and could easily happen if stirring in heat and acid for "days"

 

Good luck...

 

Edit: you may also want to check out this link regarding oxidation of secondary alcohols with sodium and calcium hypochlorite: http://www.erowid.org/archive/rhodium/chemistry/ether2ester.hypochlorite.html - and then maybe search SciFinder for some others...

 

Also.. just wondering but is your boss a classically trained synthetic chemist? That KMno4 things is kinda common knowledge as well. : (

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And you know really I know you really don't want to change the synthetic route but...

glycerol HAS to be commercially available from Aldrich or Acros or something...

 

Just buy that stuff.. they probably have one with the carbonyl already at the 3 position.. if not just oxidize that up with a reagent that is selective for just secondary alcohol i.e. NaOCl and Acetic Acid - check Carey and Sundberg part B and/or SciFinder for a reference to this reaction....

 

Then add PBr3 or something similar and then convert to the cyanos with CN-

seems like the easiest way to do this if you are certain that you CN groups are the problem although I'm quite certain chelation/coordination and/or hydrolysis are the likely causes of your difficulties...

 

Good luck...

Edited May 27, 2009 by chemist
Consecutive posts merged.

[Margel]

Chemist,

 

I now doubt if you really what you are talking about. Jones reagent is a standard oxidation reagent which works for a lot of substrates even strained molecules. Type chromium trioxide on Organic Synthesis website to know what I am talking about. The problem with Jones reagent is its selectivity. This is why PCC, PDC, Swern etc. was invented.

 

Hydrolysis of nitriles involve an excess of water. Jones oxidation is carried out with not much water. So it is really not likely that hydrolysis is the problem. Besides, the COOH peak can be easily seen in the 1H NMR spectrum.

 

My supervisor did 2 postdocs and one is with one of the editors of EROS. Using KMnO4 alone results on several oxidation problems. I agree with Sundberg and Carey on this. However KMnO4 in a solid support (like CuSO4, SiO2 or alumina) is know to be effective oxidizing agents producing high yields of the desired product.

 

But certainly, you have sone point on the nitrile coordinating with chromium so I owe one to you.

 

I already mentioned that SN2 reaction of dibromoacetone is problematic and here you are suggesting me to start with glycerol. It seems that you don't have a good eye for details.

[chemist]

Chemist,

 

I now doubt if you really what you are talking about. Jones reagent is a standard oxidation reagent which works for a lot of substrates even strained molecules. Type chromium trioxide on Organic Synthesis website to know what I am talking about. The problem with Jones reagent is its selectivity. This is why PCC, PDC, Swern etc. was invented.

 

Hydrolysis of nitriles involve an excess of water. Jones oxidation is carried out with not much water. So it is really not likely that hydrolysis is the problem. Besides, the COOH peak can be easily seen in the 1H NMR spectrum.

 

My supervisor did 2 postdocs and one is with one of the editors of EROS. Using KMnO4 alone results on several oxidation problems. I agree with Sundberg and Carey on this. However KMnO4 in a solid support (like CuSO4, SiO2 or alumina) is know to be effective oxidizing agents producing high yields of the desired product.

 

But certainly, you have sone point on the nitrile coordinating with chromium so I owe one to you.

 

I already mentioned that SN2 reaction of dibromoacetone is problematic and here you are suggesting me to start with glycerol. It seems that you don't have a good eye for details.

 

lol! Whatever you say man... - "For simple unfunctionalized alcohols, oxidations can be done by an addition of an acidic aqueous solution containing chormic acid (known as jones reagent)" - Carey & Sundberg part B see link: http://books.google.com/books?id=cbDE0prX93gC&pg=PA748&lpg=PA748&dq=problems+with+jones+reagent+in+advanced+synthesis&source=bl&ots=p6AtZeOBkV&sig=JWNRmdMCJGNeXu9lqkoQJ-iNEqg&hl=en&ei=cmQgSu6WL4KctgP3hNSWBA&sa=X&oi=book_result&ct=result&resnum=6#PPA748,M1

 

simple unfuntionalized alcohols that is not what the typical synthetic chemist works with on a daily basis.. at least that's not the case around here.. but if you're trying to oxidize 2-butanol then by all means use Jones...

 

oh and btw PCC was NOT made to improve selectivity.. tell me what alcohols would PCC be more selective for that Jones is not?

lol! PCC and the others were made because Jones is not functional group compatible - it's too harsh - and people wanted a more mild oxidizer for their complex molecules... I've used PCC on 1 and 2 alcohols and alcohols with differing energetics... selectivity in this case is substrate level and has nothing to do with reagent level control. WTF are you talking about?! PCC will oxidize the same stuff as Jones it just tends to stop before causing problems to other functionality in your molecule that whereas Jones does not...

 

- lol! I think you might have meant chemoselectivity and there isn't much of a relevant difference between these two reagents there as you're trying to oxidize a secondary alcohol so your issue is functional group compatibility despite what you think...

 

Yeah KMnO4 as a catalyst or when being used with solid support etc will work but you're not gonna get that to work on yours for reasons so obvious you should already know them...

 

This is starting to seem to me to be more your problem than the reactants... If you noticed I asked you how you did your work up.. you wouldn't see the carboxylic acid if you used water to quench your reaction.. It would be in the aqueous.. so unless you protonated and extracted accordingly - because you knew you had a COOH - then I don't know why you are expecting to see it on NMR...

 

As for the SN2 I've gotten that to work on that exact substrate so you are doing something wrong.. but if you can't get that to work you can convert to mesylates and then use CN-, and if that doesn't work you can convert the mesylates to the Iodide... etc...

 

but by all means go and try to oxidize that with KMnO4 in a solid support and see how many equivelants that takes.. lol!

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In addition to reading what Cary and Sundberg have to say about the functional group incompatibility of Jones... You may also want to check out this book scrolling down to page 4 section 1.1.5 Selection of Oxidant : http://books.google.com/books?id=O6USLyDIBOUC&pg=PA1&lpg=PA1&dq=Jones+reagent+in+organic+synthesis&source=bl&ots=7AAIPi7hik&sig=Uk5WkSSQVeB3vOnApVvl3OojoD0&hl=en&ei=pVAhSpGxNZSatAPPjKyZBA&sa=X&oi=book_result&ct=result&resnum=9#PPA4,M1

 

and also seeing this link scrolling down to page 246 section on oxidations: "Oxidation with acid solutions of chromic acid is unsuitable for alcohols which contain acid sensitive groups or other easily oxidisable groups such as olefinic bonds..." - http://books.google.com/books?id=xAc4AAAAIAAJ&pg=PA247&lpg=PA247&dq=using+Jones+Reagent+in+complex+organic+synthesis&source=bl&ots=nrUUsIAwVR&sig=JuQi2OVLdYWsq47HE2EXREljnfg&hl=en&ei=f1chSvT3CZSutgO4tYCUBA&sa=X&oi=book_result&ct=result&resnum=6#PPA121,M1

 

- remembering that Nitriles are acid labile - Duh!

 

and see this as you still seem to be confused regarding the ease of hydrolyzing a nitrile - you do NOT need excess water.. that's only something they tell you in undergrad.. with all of the equivalents you said you added of the already aqueous Jones reagent in sulfuric acid that you heated and let stir for days.. lol! - see this link for more details: http://www.mhhe.com/physsci/chemistry/carey/student/olc/graphics/carey04oc/ref/ch20reactionsnitriles.html - search for the hydrolysis reaction of nitriles and you'll see that the conditions you describe are near perfect...

 

so I think you might want to vamp up your lab skills and pay better attention during your work up to see that you are not discarding side products etc...

 

sigh...

Good luck.

Edited May 30, 2009 by chemist
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[mooeypoo]

chemist, this is a debate forum where we share our knowledge respectfully. You are, respectfully, urged to read our rules, perhaps go over some of the common netiquette forms as well, and re-evaluate the tone of your future replies.

 

I am sure you can find a way to share your knowledge with us without resorting to ridicule and be a helpful and thoughtful participant of this forum.

[chemist]

I was under the impression that I was ridiculed first...

[mooeypoo]

I was under the impression that I was ridiculed first...

 

<read this extremely fast with a radio announcer's voice>Disclaimer: The above post and everything I am saying in my capacity as a moderator does not pertain strictly to chemist himself, rather to the entire forum, its participants, or whoever decides to participate in this debate.

 

In other words: who was first is irrelevant. The rules act on everyone, and we should ALL be respectful. No infractions were issued (yet?) on this matter and so, no "harm" was done. The point was to remind everyone of the rules and of the concept of a polite debate. Everyone's encouraged to reflect on those terms, take a deep breath, and come back to talk chemistry.

 

 

Now please resume chemistry debate, which is what this thread is for.

 

Thank you.

[chemist]

Hello,

 

Well to each his own... not everyone is a good fit for everywhere...

Could you please assist me with deleting my account whenever you get a chance? I sent a PM too - or at least I think I did - since I'm trying from my black berry and I never know exactly what I'm clicking the screen is so small...

 

Thanks.

Edited June 2, 2009 by chemist