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Klaus Hafner (1979). "August Kekulé - The Architect of Chemistry Commemorating the 150th Anniversary of His Birth". Angewandte Chemie International Edition in English. 18 (9): 641–651. doi: 10.1002/anie.197906413.-- Stone 09:28, 12 March 2007 (UTC)
This article was automatically assessed because at least one article was rated and this bot brought all the other ratings up to at least that level. BetacommandBot 11:43, 27 August 2007 (UTC)
I have reworded this example to make clear that it is the chain structure is based on Kekule's ideas and not the correct structure. But I also have some historical questions:
Who proposed the chain structure and when? Kekule himself? Someone else prior to 1912 (when crystallography started)? Or a more recent textbook looking for examples where Kekule's ideas give the wrong structure?
If the chain structure was criticized prior to 1912, on what grounds was it criticized then? Of course, it was easy to criticize in Pauling's era (1930s) after the correct structure was known from crystallography. As it is easy for modern students who have learned about VSEPR and orbital hybridization. Dirac66 00:34, 31 October 2007 (UTC)
Ah yes. I had forgotten the nature of 19th-century chemical reasoning before crystallography and other physical methods. I think though that your last 3 words "possible to disprove" should be "impossible to disprove (at the time)". I think now we can try to improve the article by explaining briefly the nature of Kolbe's criticism. The focus should remain on Kekule however since it is his article. Dirac66 03:30, 1 November 2007 (UTC)
Right! impossible! We should focus on Kekule! The criticism was strong in the beginning and by 1882 when Kolbe still refused to belive that the structure of molecules should be drawn on paper the critical voices nearly deminished. The step to get the structure of the molecule only from chemical reactions and pysical measurments of bulk properties of the substances is even for me loking back a big step! It gave a lot of wrong answers, but chemistry without it would have never made the progress we saw between 1860 and 1912. -- Stone 08:14, 1 November 2007 (UTC)
I have now reworded the paragraph about HIO4 to include some of your explanations. What do you think of the following text (which I have not yet put in the article)?
The idea of a fixed number of valences for each element was one key component of the structural chemistry. This concept has proven to be wrong, especially in inorganic chemistry, and was subsequently replaced by fixed valences for each oxidation state. One often criticized example was periodic acid, HIO4. According to Kekule's ideas, iodine has one valence, oxygen two and hydrogen one, leading to an (incorrect) chain structure I-O-O-O-O-H, with each oxygen at a different distance from the iodine. In 1882 Kolbe criticized this structure (and Kekule's theory) because the chemistry of periodic acid shows no sign of inequivalent oxygens. Modern chemists realize that iodine in this molecule has seven valence (corresponding to its oxidation state), and that the correct structure has all four oxygen atoms surrounding the iodine in a tetrahedral geometry. In defence of Kekule, however, it must be noted that fixed valences are more usual in organic chemistry. Dirac66 01:41, 4 November 2007 (UTC)
I have several comments (I am the author of the only book-length modern biography of Kolbe). First, Dirac66 is right that Kekule's idea was not based on direct observations of atoms and molecules, but no chemist could do that then. No chemist can do that even today, one might legitimately say, because x-ray crystallography does not "directly observe" molecules, either. In both cases one needs to make inferences from macroscopic evidence which is gathered more or less indirectly. But Kekule's work WAS based on "direct observations", namely observations of many chemical reactions and physical properties that led him (legitimately!) to the conclusions about valence and structure theory that the article describes. So I would argue that the first paragraph of this section is a little misleading. — Ajrocke — continues after insertion below
Second, Kolbe was indeed an experimental chemist, but he was also (and really much more) a theoretical chemist too. Kekule was both experimental and theoretical, as well. Kolbe's objection was not that one could not form a theory about such matters (HE certainly had formed very many!), but rather that Kekule's particular theory was incorrect. But the most important point to keep in mind is that Kolbe had become so rabid and so abusive in his published critiques, that by 1882 no one really paid him any mind. I am quite sure that Kolbe had come to suffer some kind of personality disorder or mania, and most in the profession knew that. So I'm not sure that mentioning Kolbe's 1882 critique is really very relevant here. (By the way, do you have a reference for that critique? I don't know it offhand, and would like to look it up.) — Ajrocke — continues after insertion below
Third, I am virtually certain that Kekule never proposed the sort of chaining formula for periodic acid that is mentioned here. Others did, following Kekule, but since this is a biography of Kekule and not a discussion of the history of structure theory, I don't think it belongs here. — Ajrocke — continues after insertion below
It is absolutely true that Kekule strongly supported constant valence, which led to such ideas. So I think it is relevant to include something about this in the article. The section written by Dirac66 makes some good points, and I do not mean to suggest that it is all incorrect. But doesn't it really belong in historical section of the article on structure theory, rather than in the biographical article on Kekule? — Ajrocke — continues after insertion below
In my opinion, the rewrite offered by Dirac66 is an improvement, but still suffers from some of the same disadvantages. I commend Dirac66, but I believe that this material is better suited for a general history of chemistry, not for the biographical article on Kekule. Too much of it pertains to a period after Kekule's death. Kekule actually stopped publishing new research about 1870, anyway, so even the last 25 years of his life were not very active. The modern idea of oxidation states is not relevant to the biography. It should not be the purpose of an article on a historical figure in science to point out where that figure had it wrong (from a modern perspective). — Ajrocke — continues after insertion below
I would like to ask Dirac66 and Stone whether they would object if the paragraph were deleted? As I say, much of the material in it would be valuable in another Wikipedia article. Ajrocke 16:04, 6 November 2007 (UTC)
From Dirac66: First for anyone trying to follow the previous section. According to the discussion history, the text at the left margin is by Ajrocke, and the indented text is insertions by Stone who forgot to sign.
Perhaps each of us is partly right. I proposed above (in the first HIO4 Example section) a text to clarify Stone's edit about HIO4, with information about Kolbe from Stone's answers to my questions. However this text is too long, and I forgot my own comment above that "The focus should remain on Kekule however since it is his article." Ajrocke says that a detailed discussion of HIO4 is not relevant to Kekule (who never discussed this molecule), and proposed that the paragraph be "deleted" - from this article? or from Wiki? He then says that the material would be valuable in another article, so I think that he meant deletion from this article only. But Stone's strong reaction suggests he thought total deletion from Wiki, as he agrees the paragraph can be moved to a better place.
So I think if we forget the word "delete", there is agreement that we can move the details about HIO4 to another article. However I would not like to see it just deleted with the idea that maybe someone in the future will put it in another article. Instead I think we should first identify together the most appropriate place to insert this information. If Kolbe raised the point about HIO4, it could be mentioned in the Conflicts section of his article. Except that I am uncertain on reading Ajrocke's comment as to whether he accepts that Kolbe in fact raised this point, so perhaps Stone and Ajrocke should first try to agree on whether it was Kolbe or someone else (I can not help here - I have no access to the original sources and very little German).
Another alternative would be a more general historical article, if possible one longer than the present article on structural theory.
After the information about HIO4 has been placed in another article, then we can eliminate its mention in the Kekule article. I suggest instead mentioning that Kekule's fixed valences work well in organic chemistry but less so in inorganic chemistry, with brief mention of the early criticism by Kolbe (or someone else) as well as of the later systematic clarification of the idea of valence by Werner (and also Lewis?). Dirac66 02:55, 7 November 2007 (UTC)
Citation
{{
cite journal}}
: |pages=
has extra text (
help); Check date values in: |date=
(
help)Abstract
August Kekulé's account of his discovery of the ring or hexagonal structure of the benzene molecule--the event that ushered in the science of organic chemistry--is the single most cited personal report in psychological writings on creativity. Although his mental state has been depicted as dreaming, visual hallucination, alcoholic stupor, or hypnagogic imagery, such depictions do not cite Kekulé's original German account but rely either on secondary sources or an 1898 English translation by F. R. Japp in the "Journal of the Chemical Society." Kekulé's original account is presented together with the results of three new translations by German language experts. Comparative analysis of all translations indicates omissions in the one by Japp and significant differences. Psychological assessment indicates that Kekulé's breakthrough was due to specific forms of primarily conscious creative cognition named homospatial and janusian processes.
[I have downloaded the pdf and it is interesting. 69.228.171.150 ( talk) 06:54, 18 November 2009 (UTC)
"with the two substituted carbon atoms separated by one, two and three carbon-carbon bonds"
I) Hydrogen is substituted not carbon so this needs clarification. II) Seems to me it would be clearer to talk about carbons instead of carbon-carbon bonds as in http://en.wikipedia.org/wiki/Arene_substitution_pattern where its said "In ortho-substitution, two substituents occupy positions next to each other". Then in meta there is one carbon inbetween and in para 2 carbons. 80.222.46.182 ( talk) 17:52, 15 October 2013 (UTC)
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Klaus Hafner (1979). "August Kekulé - The Architect of Chemistry Commemorating the 150th Anniversary of His Birth". Angewandte Chemie International Edition in English. 18 (9): 641–651. doi: 10.1002/anie.197906413.-- Stone 09:28, 12 March 2007 (UTC)
This article was automatically assessed because at least one article was rated and this bot brought all the other ratings up to at least that level. BetacommandBot 11:43, 27 August 2007 (UTC)
I have reworded this example to make clear that it is the chain structure is based on Kekule's ideas and not the correct structure. But I also have some historical questions:
Who proposed the chain structure and when? Kekule himself? Someone else prior to 1912 (when crystallography started)? Or a more recent textbook looking for examples where Kekule's ideas give the wrong structure?
If the chain structure was criticized prior to 1912, on what grounds was it criticized then? Of course, it was easy to criticize in Pauling's era (1930s) after the correct structure was known from crystallography. As it is easy for modern students who have learned about VSEPR and orbital hybridization. Dirac66 00:34, 31 October 2007 (UTC)
Ah yes. I had forgotten the nature of 19th-century chemical reasoning before crystallography and other physical methods. I think though that your last 3 words "possible to disprove" should be "impossible to disprove (at the time)". I think now we can try to improve the article by explaining briefly the nature of Kolbe's criticism. The focus should remain on Kekule however since it is his article. Dirac66 03:30, 1 November 2007 (UTC)
Right! impossible! We should focus on Kekule! The criticism was strong in the beginning and by 1882 when Kolbe still refused to belive that the structure of molecules should be drawn on paper the critical voices nearly deminished. The step to get the structure of the molecule only from chemical reactions and pysical measurments of bulk properties of the substances is even for me loking back a big step! It gave a lot of wrong answers, but chemistry without it would have never made the progress we saw between 1860 and 1912. -- Stone 08:14, 1 November 2007 (UTC)
I have now reworded the paragraph about HIO4 to include some of your explanations. What do you think of the following text (which I have not yet put in the article)?
The idea of a fixed number of valences for each element was one key component of the structural chemistry. This concept has proven to be wrong, especially in inorganic chemistry, and was subsequently replaced by fixed valences for each oxidation state. One often criticized example was periodic acid, HIO4. According to Kekule's ideas, iodine has one valence, oxygen two and hydrogen one, leading to an (incorrect) chain structure I-O-O-O-O-H, with each oxygen at a different distance from the iodine. In 1882 Kolbe criticized this structure (and Kekule's theory) because the chemistry of periodic acid shows no sign of inequivalent oxygens. Modern chemists realize that iodine in this molecule has seven valence (corresponding to its oxidation state), and that the correct structure has all four oxygen atoms surrounding the iodine in a tetrahedral geometry. In defence of Kekule, however, it must be noted that fixed valences are more usual in organic chemistry. Dirac66 01:41, 4 November 2007 (UTC)
I have several comments (I am the author of the only book-length modern biography of Kolbe). First, Dirac66 is right that Kekule's idea was not based on direct observations of atoms and molecules, but no chemist could do that then. No chemist can do that even today, one might legitimately say, because x-ray crystallography does not "directly observe" molecules, either. In both cases one needs to make inferences from macroscopic evidence which is gathered more or less indirectly. But Kekule's work WAS based on "direct observations", namely observations of many chemical reactions and physical properties that led him (legitimately!) to the conclusions about valence and structure theory that the article describes. So I would argue that the first paragraph of this section is a little misleading. — Ajrocke — continues after insertion below
Second, Kolbe was indeed an experimental chemist, but he was also (and really much more) a theoretical chemist too. Kekule was both experimental and theoretical, as well. Kolbe's objection was not that one could not form a theory about such matters (HE certainly had formed very many!), but rather that Kekule's particular theory was incorrect. But the most important point to keep in mind is that Kolbe had become so rabid and so abusive in his published critiques, that by 1882 no one really paid him any mind. I am quite sure that Kolbe had come to suffer some kind of personality disorder or mania, and most in the profession knew that. So I'm not sure that mentioning Kolbe's 1882 critique is really very relevant here. (By the way, do you have a reference for that critique? I don't know it offhand, and would like to look it up.) — Ajrocke — continues after insertion below
Third, I am virtually certain that Kekule never proposed the sort of chaining formula for periodic acid that is mentioned here. Others did, following Kekule, but since this is a biography of Kekule and not a discussion of the history of structure theory, I don't think it belongs here. — Ajrocke — continues after insertion below
It is absolutely true that Kekule strongly supported constant valence, which led to such ideas. So I think it is relevant to include something about this in the article. The section written by Dirac66 makes some good points, and I do not mean to suggest that it is all incorrect. But doesn't it really belong in historical section of the article on structure theory, rather than in the biographical article on Kekule? — Ajrocke — continues after insertion below
In my opinion, the rewrite offered by Dirac66 is an improvement, but still suffers from some of the same disadvantages. I commend Dirac66, but I believe that this material is better suited for a general history of chemistry, not for the biographical article on Kekule. Too much of it pertains to a period after Kekule's death. Kekule actually stopped publishing new research about 1870, anyway, so even the last 25 years of his life were not very active. The modern idea of oxidation states is not relevant to the biography. It should not be the purpose of an article on a historical figure in science to point out where that figure had it wrong (from a modern perspective). — Ajrocke — continues after insertion below
I would like to ask Dirac66 and Stone whether they would object if the paragraph were deleted? As I say, much of the material in it would be valuable in another Wikipedia article. Ajrocke 16:04, 6 November 2007 (UTC)
From Dirac66: First for anyone trying to follow the previous section. According to the discussion history, the text at the left margin is by Ajrocke, and the indented text is insertions by Stone who forgot to sign.
Perhaps each of us is partly right. I proposed above (in the first HIO4 Example section) a text to clarify Stone's edit about HIO4, with information about Kolbe from Stone's answers to my questions. However this text is too long, and I forgot my own comment above that "The focus should remain on Kekule however since it is his article." Ajrocke says that a detailed discussion of HIO4 is not relevant to Kekule (who never discussed this molecule), and proposed that the paragraph be "deleted" - from this article? or from Wiki? He then says that the material would be valuable in another article, so I think that he meant deletion from this article only. But Stone's strong reaction suggests he thought total deletion from Wiki, as he agrees the paragraph can be moved to a better place.
So I think if we forget the word "delete", there is agreement that we can move the details about HIO4 to another article. However I would not like to see it just deleted with the idea that maybe someone in the future will put it in another article. Instead I think we should first identify together the most appropriate place to insert this information. If Kolbe raised the point about HIO4, it could be mentioned in the Conflicts section of his article. Except that I am uncertain on reading Ajrocke's comment as to whether he accepts that Kolbe in fact raised this point, so perhaps Stone and Ajrocke should first try to agree on whether it was Kolbe or someone else (I can not help here - I have no access to the original sources and very little German).
Another alternative would be a more general historical article, if possible one longer than the present article on structural theory.
After the information about HIO4 has been placed in another article, then we can eliminate its mention in the Kekule article. I suggest instead mentioning that Kekule's fixed valences work well in organic chemistry but less so in inorganic chemistry, with brief mention of the early criticism by Kolbe (or someone else) as well as of the later systematic clarification of the idea of valence by Werner (and also Lewis?). Dirac66 02:55, 7 November 2007 (UTC)
Citation
{{
cite journal}}
: |pages=
has extra text (
help); Check date values in: |date=
(
help)Abstract
August Kekulé's account of his discovery of the ring or hexagonal structure of the benzene molecule--the event that ushered in the science of organic chemistry--is the single most cited personal report in psychological writings on creativity. Although his mental state has been depicted as dreaming, visual hallucination, alcoholic stupor, or hypnagogic imagery, such depictions do not cite Kekulé's original German account but rely either on secondary sources or an 1898 English translation by F. R. Japp in the "Journal of the Chemical Society." Kekulé's original account is presented together with the results of three new translations by German language experts. Comparative analysis of all translations indicates omissions in the one by Japp and significant differences. Psychological assessment indicates that Kekulé's breakthrough was due to specific forms of primarily conscious creative cognition named homospatial and janusian processes.
[I have downloaded the pdf and it is interesting. 69.228.171.150 ( talk) 06:54, 18 November 2009 (UTC)
"with the two substituted carbon atoms separated by one, two and three carbon-carbon bonds"
I) Hydrogen is substituted not carbon so this needs clarification. II) Seems to me it would be clearer to talk about carbons instead of carbon-carbon bonds as in http://en.wikipedia.org/wiki/Arene_substitution_pattern where its said "In ortho-substitution, two substituents occupy positions next to each other". Then in meta there is one carbon inbetween and in para 2 carbons. 80.222.46.182 ( talk) 17:52, 15 October 2013 (UTC)
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The following Wikimedia Commons file used on this page has been nominated for deletion:
Participate in the deletion discussion at the nomination page. — Community Tech bot ( talk) 17:25, 17 October 2018 (UTC)