Talk:Hydrophobic effect

Inadequate

The article mentions nothing about other theories on the thermodynamics of the hydrophobic effect. It soley gives the classical explanation (e.g. one promising theory was formulated by Peter Privalov. Privalov came to the conclusion that the hydrophobic effect cannot be entropy driven!). Therefore, the article does not qualify as a "good article". Also, there is a huge lack in use of references... —Preceding unsigned comment added by 77.53.104.235 (talk) 14:11, 27 May 2009 (UTC)

This article was a GA nominee 05:38, 25 April 2009 (UTC): ArticleName (edit | talk | history | protect | delete | links | watch | logs | views) The hope (talk) 05:38, 25 April 2009 (UTC)

The statement that the hydrophobic effect is entropic is negated directly thereafter when the author states that it originates from disruption of hydrogen bonds in water. It seems that the author is alluding to the idea that hydrophobes aggregate to minimize the surface area that is in contact with water thus disrupting less of the hydrogen bonding network. That is an enthalpic effect. — Preceding unsigned comment added by Wrww (talk • contribs) 14:25, 19 October 2011 (UTC)

The effect is in fact mostly enthalpic, not entropic. According to this 'Nature' article http://www.nature.com/nature/journal/v437/n7059/pdf/nature04162.pdf in clusters larger than 1nm (volume/surface area) the effect is mostly enthalpic. This is the case in most systems. 89.139.22.109 (talk) 15:58, 23 December 2011 (UTC)

The title concept refers to an historical construct of Walter Kauzmann and Charlie Tanford, of a temperature-dependent effect that is entropic in largest part at ambient (biologically relevant) temperatures. Period.

• http://www.asbmb.org/uploadedFiles/AboutUs/ASBMB_History/Charles%20Tanford.pdf
• http://www.amazon.com/Hydrophobic-Effect-Formation-Biological-Membranes/dp/0471048933/ref=sr_1_1?s=books&ie=UTF8&qid=1400552554&sr=1-1&keywords=9780471048930

How the term has evolved based on further studies and modernization of language, theory, and application (e.g., by Ken DIll and others), since the extensive seminal studies of Tanford—these matters are also relevant, but not without understanding of the Tanford work as foundation. As it stands, the article confounds the Tanford concept with various other physical and biophysical terms in use today in chemistry/biochemistry, especially in protein science. The commentators and contributors here, esp. those making the last two definitive statements, are clearly not physical chemists or physical biochemists, and for the most part are not adequately informed to make the definitive pronouncements that are being offered (e.g., "that the hydrophobic effect is entropic is negated" and "effect is in fact mostly enthalpic, not entropic"). As it stands, this article is one more hodgepodge of material, put together by individuals with neither the historical understanding or the chemical scope to construct an adequate description of the origin, evolution, and proper applications of the title term. See also closing new section, dated today. Le Prof Leprof 7272 (talk) 02:17, 20 May 2014 (UTC)

The introductory paragraph for this article states: "The hydrophobic effect is the observed tendency of nonpolar substances to aggregate in aqueous solution and exclude water molecules.[1][2] This occurs because interactions between the hydrophobic molecules enable the displaced water molecules to make hydrogen bonds more freely with each other and increase the number of hydrogen bonds they are involved with, thereby decreasing the overall free energy."

This is really badly written. In fact, the first sentence is an almost perfect inversion of the actual hydrophobic effect, which is the tendency of water to exclude nonpolar molecules, not the tendency of nonpolar molecules to exclude water. The statement that the hydrophobic effect occurs because of "interactions between hydrophobic molecules" is incorrect. The driving force for the hydrophobic effect comes from the free energy effects of disruption of the hydrogen bond network in water, not from "interactions between hydrophobic molecules." Technically, there is no such thing as a "hydrophobic molecule." Overall, this is just a really bad article. -- David J. Wright, PhD (PS: I knew the late Charles Tanford, he was one of my professors in graduate school).2601:18C:1:B10A:FD4A:A693:8A5D:FAD7 (talk) 21:21, 21 May 2016 (UTC)

Clarify "zero degrees"

Resolved

 – Shanata (talk) 13:20, 4 March 2009 (UTC)

I just wanted to note that "zero degrees" should be clarified, so as not to be confused with absolute zero. Presumably, the author means to say "zero degrees Celsius (273 Kelvin)". I'll have to look into the actual answer before I edit though.

Drawing

I think that a drawing on the molecular level of molecules under the hydrophobic effect might help people to better understand it.

Lacks references

This page has a lot of rather specific information that needs to be referenced. M stone 22:34, 21 April 2007 (UTC)

Yes, including the statement which you replaced without comment today about the tertiary structure of DNA, which has been tagged as unreferenced since 14 April 2008. Yesterday, it was removed by user 67.180.9.111 with the edit summary "Removing erroneous statement about DNA: There is no evidence that this charged, highly polar molecule exhibits the hydrophobic effect". I think that since we have waited 1.5 years for a reference, and since 67.180.9.111 has given a serious reason for deletion, that this statement should not have been put back without evidence. I propose to wait a few days and then remove it again if no evidence has been supplied. Dirac66 (talk) 15:14, 24 September 2009 (UTC)

This is really common knowledge. Tagging something as unreferenced is fine for someone who really doesn't know anything about the subject. Please don't delete something just because you don't understand it. The charges go on the outside of the double helix and the hydrophobic aromatic base pairs are on the inside where they minimize contact with water. I have added a ref ("Basic Concepts in Biochemistry - A Student's Survival Guide by Gilbert, H.F." on page 9) that can be previewed on the Google books. I hope that this reference satisfies your concerns. M stone (talk) 19:34, 24 September 2009 (UTC)

Thanks for adding a reference to a biochemistry study guide which supports the claim and suggests a consensus in introductory biochemistry texts. Common knowledge of the DNA structure does not really show that the hydrophobic effect keeps the base pairs on the inside, since there are of course two other major factors keeping them on the inside: the hydrogen bonds and the ionic stabilization of the phosphates on the outside. Gilbert only mentions DNA parenthetically in a paragraph (and a chapter) about proteins where the hydrophobic nature of alkyl side chains is much clearer.

I will leave the paragraph alone since your reference does show that it is accepted in introductory biochemistry. But as a physical chemist, I would prefer to also see a reference to the experimental evidence for a hydrophobic effect in this system. I think this was what user 67.180.9.111 meant in his/her edit summary. Dirac66 (talk) 03:05, 25 September 2009 (UTC)

OK, after a trip to the library I have now added another reference to a book with an initial statement similar to Gilbert's in chapter 1, plus more detailed thermodynamic discussion in chapter 3. This makes more background information available to the interested reader. Dirac66 (talk) 00:22, 5 October 2009 (UTC)

Confounded concepts

I placed the expert needed tag. I have taught this concept, and while not a specialist in this research, I have come close enough to it over the years to have discussed it with contemporary major experimentalists and theorists working on the matter. As it stands, the article confounds the Tanford concept with various other physical and biophysical terms in use today in chemistry/biochemistry, especially in protein science. As such, the article misses the crux of the matter entirely—and is clearly far too beholden to student contributors whose perspectives have been shaped by the reading of a single or few more recent articles on the subject, or perhaps on the opinion of a single teacher (see below for the frontal assault on this).

Both from an historical and a physical chemistry perspective, the title concept was a construct of Kauzmann and Tanford, of primarily an effect that is, at room temperature, essentially an entropic effect. See above for an Amazon link to the 2nd edition of the seminal Tanford text. Here is a brief, in memoriam, about Tanford:

• http://www.asbmb.org/uploadedFiles/AboutUs/ASBMB_History/Charles%20Tanford.pdf

Key to understanding the total concept is appreciation of the temperature dependence of the relevant thermodynamic expressions of affinity of the apolar molecule or moiety (e.g., a neopentane molecule, an apolar amino acid side chain, etc.) for an aqueous phase, and the fact that the Δh (enthalpic term) term therein is nearly zero at ambient temperature, such that the affinity is driven by the entropic term, tΔs (see Fig 2 in the bulleted Dill article at hiraoka.c.u-tokyo.ac.jp, below).

As I state above, the controversies that the original thermodynamic proposal generated and how the title concept has evolved—with further studies since the extensive originating and seminal studies of Tanford—are also relevant, but not without the (essentially missing!) Tanford work as foundation. The commentators and contributors in this Talk (and seemingly in the article) are not adequately informed to make the definitive, cursory pronouncements offered above (e.g., "that the hydrophobic effect is entropic is negated" and "effect is in fact mostly enthalpic, not entropic"), and this naiveté has clearly impacted the article that appears. As such, the current article is a near useless hodgepodge without adequate description of the origin, evolution, and proper applications of the title term. For these reasons, a subject matter expert has been requested. Rarely here have I been this angry over an "academic" content matter. Le Prof Leprof 7272 (talk) 02:33, 20 May 2014 (UTC)

As I have time I will begin to append articles here that, in addition to the 2nd edition Tanford text, will allow readers to begin to understand this concept in its original context:

• http://www.physics.uoguelph.ca/~dutcher/download/nano_4100/cd/lipids%20proteins%20and%20membranes/tanford_Science_78.pdf Le Prof Leprof 7272 (talk) 02:46, 20 May 2014 (UTC)
• http://hiraoka.c.u-tokyo.ac.jp/molecularinteraction/Resources/%2303c_JPCB_2002_106p521.pdf Bravo Ken et al. Others, read this and LEARN. Figure 2 is key. Note, Dill et al. cite Walter Kauzmann as being the earlier source of the concept that was then pursued by Tanford (see next bullet). Le Prof Leprof 7272 (talk) 03:06, 20 May 2014 (UTC)
• http://www.engineering.ucsb.edu/~saleh/Teaching/bioforce2012/dill1995-OCR.pdf On nonlocal forces, including the hydrophobic effect, in protein folding. Le Prof Leprof 7272 (talk) 03:26, 20 May 2014 (UTC)
• http://onlinelibrary.wiley.com/store/10.1002/pro.5560060627/asset/5560060627_ftp.pdf?v=1&t=hvfs7o7h&s=0d1201eeb98828c3f4e9a61582f5452ad7064a26 This is C. Tanford, 1997, "How protein chemists learned about the hydrophobic factor," Protein Science (Cambridge University Press), 6:1358-1366. This is a scholarly, non-self-aggrandizing personal description of the development of ideas regarding protein folding from 1930-1960, and it is ripe with insight and personal perspective of the right sort. It takes the story through until the the contribution of the hydrophobic effect, and the dipole-dipole interaction of the hydrogen bond reach a settled understanding and are near to accepted theory. The only brief foray more to the present is a deserved gentle thrashing of Privalov and Gill (which our confident student contributors should take to heart). That something is published does not make it correct; without the experience or hard work to discern the true preponderance of relevant scientific opinion—of the players who ought to be trusted with your faith in the final understanding—there is no chance of "getting it right". (Though the majority will at times get it wrong, Tanford, Dill, etc. etc., have not.) Le Prof Leprof 7272 (talk) 00:41, 21 May 2014 (UTC)

I think that since you seem to have read more on the subject than most other editors of this article, it would probably help if you assume the role of expert yourself and try to improve the article as much as you can. And please don't be angry with confused students who are trying their best - le prof doit être patient avec les étudiants! Dirac66 (talk) 00:54, 21 May 2014 (UTC)

This is a good article. It provides a lot of information. It does not need to be perfect or conform to one particular point of view on the subject. Please add content to the article instead of tags. I am removing the tag because I do not think that it applies. M stone (talk) 23:32, 22 May 2014 (UTC)

Nevertheless it mixes different concepts and pretends to know the ultimative answer. This is not concensus in science today. Entropy as the origin of the hydrophobic effect is disputed!!--92.204.107.5 (talk) 19:48, 24 May 2014 (UTC)

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Narrow scope?

This article seems to be limited to biological effects. What about all the industrial applications, such as hydrophobic concrete (I am no expert, but there must be many other examples as well). --Remotelysensed (talk) 13:15, 4 May 2017 (UTC)