Changes
Dec,31,2007 Filed in: Chemistry | Publishing
Well, I knew I wouldn't be a big
blogger. Let me update you on what has been happening (or not). In
some ways, I too wonder, what the heck I have been doing.
I have been answering a lot of student questions on various web forums. This included my own. An additional word about this. My webforum was becoming heavily spammed and I wanted to cure that. I was looking for some phpBB hack that I could use. Long story short, my ISP was un-helpful, I changed my forum software twice and now operate with punBB. It hasn't been spammed yet and future is to install some hacks to moderate forum and block spammers.
Answering questions tells me two things. One, it tells me the kinds of questions or problems that students are having ...
I have been answering a lot of student questions on various web forums. This included my own. An additional word about this. My webforum was becoming heavily spammed and I wanted to cure that. I was looking for some phpBB hack that I could use. Long story short, my ISP was un-helpful, I changed my forum software twice and now operate with punBB. It hasn't been spammed yet and future is to install some hacks to moderate forum and block spammers.
Answering questions tells me two things. One, it tells me the kinds of questions or problems that students are having ...
Well, I knew I wouldn't be a big
blogger. Let me update you on what has been happening (or not). In
some ways, I too wonder, what the heck I have been doing.
I have been answering a lot of student questions on various web forums. This included my own. An additional word about this. My webforum was becoming heavily spammed and I wanted to cure that. I was looking for some phpBB hack that I could use. Long story short, my ISP was un-helpful, I changed my forum software twice and now operate with punBB. It hasn't been spammed yet and I have yet to install some hacks to moderate the forum and block spammers.
Answering questions tells me two things. One, it tells me the kinds of questions or problems that students are having the most difficulty with. Secondly, it tells me how successful I might be in getting adoptions. The reality is that many professors just do not teach in the manner I did. If I am to be successful, I should target professors that are committed to teaching mechanisms. I have been editing my book quite heavily. In come cases, I have been able to drop some content and in other areas, I am adding content. Most in need of additions are SN1, SN2, E1, and E2 reactions. This area is especially problematic. I have been able to get a general appreciation for these reactions, but some aspects still elude me. If I were a student, I would not know what to do.
Here is an example. Reusch has on his website that in an SN1/E1 reaction, one has little ability to predict the product of the reaction. Examples show that if you did an SN1 substitution of t-butyl iodide in water + organic, you would get t-butanol plus isobutylene. If you used t-butyl chloride, you get the same products, but in different ratios. Okay, so with the same intermediate, there is little I can do the get one product or the other. If you treat t-butyl iodide with sodium ethoxide, you get isobutylene. Okay, this must be an E2 elimination. If you treat t-butyl iodide with sodium hydroxide in water + organic, you get isobutylene. There we have it, is the really an E2 reaction or an E1 reaction that disagrees with prior statement? In lab, we had done the solvolysis reaction as described by Frank Creegan, a POGIL experiment. The reaction was consistent with an E1 reaction.
I reviewed a lot of reactions and looked for trends. This was also not encouraging. I am certain that much of the chemistry community thinks of reactions as being concerted, that is, all of the electrons moving at the same time. Looking at E1 and E2 data suggests to me that this would be a difficult premise to maintain. I have suggested that SN1 and SN2 reactions might be considered as one of two extremes, bond formation precedes bond cleavage or bond cleavage is complete and no remnants of the leaving ion are present to influence the formation of product. Those are the extremes and all of the reactions you face are somewhere between those extremes. I think this is a pretty realistic description. This agrees with the Hammond postulate that bond making and breaking can occur to different amounts and at different timing. I interpret this to mean these reactions are not concerted as in the time is the same for all and occurs at the same time. That too seems pretty obvious.
If we extend the notion of different timing for SN1 and SN2 reactions in which two pair of electrons are moving at different rates, what would you guess would be the consequence of adding an additional set of electrons? Would anyone be surprise that the differences in rates show in SN1 and SN2 reactions are now extended in E2 reactions because an additional set of electrons are now involved? That appears to provide the grounds for the best explanations of the reaction products one finds. Some reactions appear to be driven by proton removal being of greatest contribution, for example t-butoxide base, or fluorides and Hofmann leaving group eliminations. Others are more dominated by the leaving group pulling electron density away and the product be determined by the neighboring groups being able to donate electrons. This leads to the Zaitsev products. I don't know if that concept can or will make it into my book or not.
Snippets, I had started on a shortened version of TLOC in which questions are removed. It will just be a pattern book of mechanisms.
I spend a lot of my thinking about my more heretical next book, "The Nature of the Chemical Bond--Revisited ..." It is difficult for me to avoid the topics as I think they are correct descriptions of the atom and help to explain mechanisms.
I taught the second session of organic this summer. I feared my students were not going to do very well. Not true, I still succeed in bringing the lower students up beyond the average of my predecessor and some of my early teaching.
My website is in need of an update. I slowly am becoming aware of how to market my book. I just have to get things done.
I just killed my heavily spammed email accounts. I found a model for what I plan, see http://nilrogsplace.se/tutorials/contactform/index.html. In Roger's tutorial, he links to some good information. Specifically, how spammers can hijack a simple form such as this and what to do about it. That is my future.
Well, back to work.
I have been answering a lot of student questions on various web forums. This included my own. An additional word about this. My webforum was becoming heavily spammed and I wanted to cure that. I was looking for some phpBB hack that I could use. Long story short, my ISP was un-helpful, I changed my forum software twice and now operate with punBB. It hasn't been spammed yet and I have yet to install some hacks to moderate the forum and block spammers.
Answering questions tells me two things. One, it tells me the kinds of questions or problems that students are having the most difficulty with. Secondly, it tells me how successful I might be in getting adoptions. The reality is that many professors just do not teach in the manner I did. If I am to be successful, I should target professors that are committed to teaching mechanisms. I have been editing my book quite heavily. In come cases, I have been able to drop some content and in other areas, I am adding content. Most in need of additions are SN1, SN2, E1, and E2 reactions. This area is especially problematic. I have been able to get a general appreciation for these reactions, but some aspects still elude me. If I were a student, I would not know what to do.
Here is an example. Reusch has on his website that in an SN1/E1 reaction, one has little ability to predict the product of the reaction. Examples show that if you did an SN1 substitution of t-butyl iodide in water + organic, you would get t-butanol plus isobutylene. If you used t-butyl chloride, you get the same products, but in different ratios. Okay, so with the same intermediate, there is little I can do the get one product or the other. If you treat t-butyl iodide with sodium ethoxide, you get isobutylene. Okay, this must be an E2 elimination. If you treat t-butyl iodide with sodium hydroxide in water + organic, you get isobutylene. There we have it, is the really an E2 reaction or an E1 reaction that disagrees with prior statement? In lab, we had done the solvolysis reaction as described by Frank Creegan, a POGIL experiment. The reaction was consistent with an E1 reaction.
I reviewed a lot of reactions and looked for trends. This was also not encouraging. I am certain that much of the chemistry community thinks of reactions as being concerted, that is, all of the electrons moving at the same time. Looking at E1 and E2 data suggests to me that this would be a difficult premise to maintain. I have suggested that SN1 and SN2 reactions might be considered as one of two extremes, bond formation precedes bond cleavage or bond cleavage is complete and no remnants of the leaving ion are present to influence the formation of product. Those are the extremes and all of the reactions you face are somewhere between those extremes. I think this is a pretty realistic description. This agrees with the Hammond postulate that bond making and breaking can occur to different amounts and at different timing. I interpret this to mean these reactions are not concerted as in the time is the same for all and occurs at the same time. That too seems pretty obvious.
If we extend the notion of different timing for SN1 and SN2 reactions in which two pair of electrons are moving at different rates, what would you guess would be the consequence of adding an additional set of electrons? Would anyone be surprise that the differences in rates show in SN1 and SN2 reactions are now extended in E2 reactions because an additional set of electrons are now involved? That appears to provide the grounds for the best explanations of the reaction products one finds. Some reactions appear to be driven by proton removal being of greatest contribution, for example t-butoxide base, or fluorides and Hofmann leaving group eliminations. Others are more dominated by the leaving group pulling electron density away and the product be determined by the neighboring groups being able to donate electrons. This leads to the Zaitsev products. I don't know if that concept can or will make it into my book or not.
Snippets, I had started on a shortened version of TLOC in which questions are removed. It will just be a pattern book of mechanisms.
I spend a lot of my thinking about my more heretical next book, "The Nature of the Chemical Bond--Revisited ..." It is difficult for me to avoid the topics as I think they are correct descriptions of the atom and help to explain mechanisms.
I taught the second session of organic this summer. I feared my students were not going to do very well. Not true, I still succeed in bringing the lower students up beyond the average of my predecessor and some of my early teaching.
My website is in need of an update. I slowly am becoming aware of how to market my book. I just have to get things done.
I just killed my heavily spammed email accounts. I found a model for what I plan, see http://nilrogsplace.se/tutorials/contactform/index.html. In Roger's tutorial, he links to some good information. Specifically, how spammers can hijack a simple form such as this and what to do about it. That is my future.
Well, back to work.
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