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{Chemical drawing needed} - Notice removed as drawing has been added. Dirac66 03:07, 1 November 2007 (UTC)

Would whoever posted this notice please indicate what drawing exactly is requested and why? There are many possible structures and reactions which could be illustrated.Dirac66 01:51, 29 October 2007 (UTC)

After writing the above I checked the history and found that the notice was posted by a bot, whose owner has since informed me that the posting is based on this discussion, based on the suggestion that EVERY article in the category Chemical Compounds needs a picture.

So do the editors of this article feel it needs a picture? If so, my suggestion would be the anhydrous (blue) and hydrated (pink) forms of Cobalt (II) chloride, which are used to detect moisture. Would anyone like to copy the images from the CoCl2 article to this article? Are there other suggestions? Dirac66 02:33, 30 October 2007 (UTC)

Opposite of hydrate[edit]

"The opposite of a hydrate is an anhydrate, such substances contain no water or form no water upon heating." I am pritty sure they can from water from heating but, but the prosses is ireversible, for instance when sucrose caramleizes.

I have now rewritten this sentence to include the possibility of loss of further water upon strong heating. Dirac66 19:49, 28 October 2007 (UTC)

In computer science, hydrate is analogous to deserialization, the opposite of which is serialization. —Preceding unsigned comment added by (talk) 22:14, 11 April 2008 (UTC)

Recent Edit For Fire Protection and Construction Issues[edit]

As far as the removal of the reference box: I also did not see a book or a website reference, but this is pretty basic chemistry. The references to construction, passive fire protection, refractories, such as sodium silicate and space physics are all internal to Wikipedia by now. As far as the hydration energy, there is more than one way to look at that. If you look at the topic of heat of hydration in cement chemistry, as well as the energy it takes to liberate hydrates, which thus takes energy photons away from the fire or the heat that is experienced during atmosspheric re-entry, it will shed light on the subject matter.--Achim 22:29, 4 May 2006 (UTC)

I'm very unclear about the appropriateness of substances such as Ethanol as a hydrate in the sense that the water can be eliminated. Clearly Ethanol is usually found bound with water (cf. anhydrous alcohol) which can be eliminated to a degree by distallation --- but the substance itself I'm not so sure. Now I understand that Ethyl Hydrate is sometimes used as synonym to Ethanol but I think the distinction should be made more clearly - what do others think? The same surely applies to hydroxide. Water cannot be removed from a hydroxide - any more than an oxide or a carbonate (except of course where there is molecular water integrated into the crystal structure). CustardJack 11:43, 11 May 2005 (UTC)

Am I correct in assuming that hydration energy is the enrgy in Hydrates? Or merely the energy in water? Bug 09:18, 16 December 2005 (UTC)


Or perhaps factories? OlavN 07:21, 6 July 2007 (UTC)

== Claim of contradiction ==lddldlldlldl;safk

User MrBell has added (23:31 and 23:34, 8 July 2009) a Contradict Template and hidden comment as follows:

Contradiction: why is ethanol considered ethylene hydrate (CH2=CH2-OH2) but methanol cannot be considered methyl hydrate (CH3-OH2)?

I have moved this to the discussion page where it is more appropriate to answer.

Answer: The experimental formulas and structures of ethanol and methanol have been determined by methods which are too long to explain here, but can be found in textbooks of organic chemistry. Ethanol is CH3-CH2-OH or H-CH2-CH2-OH, with the same overall formula (C2H6O) as you have written but a different structure. It corresponds to adding H to one C and OH to the other C, so that the overall molecule added to H2C=CH2 is H2O and it is therefore a hydrate of ethylene.

For methanol the correct structure is CH3-OH and not CH3-OH2. Oldest experimental proof: combustion analysis gives empirical formula CH4O and not CH5O. Modern proof: proton NMR spectroscopy. Also there are the rules of chemical valence, since CH3-OH2 would have an unstable trivalent neutral oxygen. Dirac66 (talk) 03:20, 9 July 2009 (UTC)

Clathrates in two sections[edit]

Today a paragraph on clathrates was added to the organic section. But we already have a paragraph on clathrates in the inorganic section which has some of the same material. It would be better to have it all in one place. I suggest a separate section for all the clathrate material, since clathrate hydrates of organic and inorganic molecules resemble each other more strongly than they resemble other types of organic and inorganic hydrates. In fact that is probably why methane clathrate was already in the "inorganic" section. Dirac66 (talk) 02:19, 10 September 2010 (UTC)

No comments on the above after 3 months, so I have now combined the two existing clathrate paragraphs in one new section. It needs more editing to eliminate the duplication and inconsistencies, but first I have two questions:
1) The second paragraph (moved from the organic section) says that nonpolar molecules form clathrate hydrates, but then gives THF which is (somewhat) polar as an example. Also the examples in the clathrate hydrate article include H2S. Should we say that the guest molecules are usually nonpolar? Or that guests are nonpolar or slightly polar?
2) The same paragraph says that guest molecules which form H-bonds include cyclopentane and THF. How can cyclopentane (an unsubstituted hydrocarbon) form H-bonds?? If this is an error, what is meant, please? Dirac66 (talk) 22:22, 15 December 2010 (UTC)
I apologize in my huge delay in responding to this. When I added this information (with citation) last September, I had free on-line access to the article I was citing. But the article now requires purchase (which I am unwilling to do). I do not believe that I would have provided incorrect information, but I am unable to substantiate this now. So I defer to your edit, Dirac66. --Ben Best (talk) 15:13, 4 February 2011 (UTC)
I don't have free access to J.Chem.Phys. either, but I have found a free abstract for the article in question here. It does mention five guest molecules starting with cyclopentane and THF, but then goes on to say that only THF and THP (tetrahydropyran) form H-bonds with the cage water hydrogen atoms of the clathrate, while the other 3 guests considered (including cyclopentane) do not. This supports my deletion of cyclopentane as an H-bond former. Dirac66 (talk) 17:23, 4 February 2011 (UTC)

Maybe useful here or at water of Crystalisation[edit]

There is a section on terminology, but I think it would be useful to indicate how hydrates are named eg penta- decca etc. anyone else agree a brief list of the why and wherefore would be useful. — Preceding unsigned comment added by Merlin-UK (talkcontribs) 13:29, 1 December 2012 (UTC)

There was a list of numerical prefixes (mono, di, tri, etc.) in the inorganic section. I have added the corresponding numbers to make it clearer. Dirac66 (talk) 18:58, 1 December 2012 (UTC)


I dont know how to rewrite the lead, but an organic hydrate doesnt necessary contain water. Ethanol does not contain water. Maybe the inorganic part should be merged with Water of crystallizationChristian75 (talk) 21:02, 22 March 2014 (UTC)

I will change the lead to say water or its elements as in the organic section. Ethanol is more often described as the product of the hydration reaction of ethene.
The inorganic part I would prefer to leave as is, since the term hydrate is used in inorganic chemistry, and water of crystallization is not an obvious place to look. Dirac66 (talk) 19:29, 23 March 2014 (UTC)

Distinction between different usages of "hydrate"[edit]

In a recent edit, I tried to clarify the multiple usages of "hydrate" more sharply.

Under Organic Chemistry, there are three usages, the third one being "frozen-in historical usages".

(1) Is the first usage under Organic Chemistry (the product of a hydration reaction) really a very common and productive usage of "hydrate"? It says that ethanol can be considered as the ethene of hydrate. Is this just an academic point or do people actually express it this way?

(2) The second usage under Organic Chemistry (water that gets trapped in a crystal) seems to be quite similar to the usage under Inorganic Chemistry.

I did notice that Water of Crystallization, while referenced here under Organic Chemistry, deals exclusively with inorganic hydrates. So there might be a reason to treat these two usages separately. But if the relationship is real, it should at least be acknowledged and discussed.

Alternately, perhaps the division into Organic Chemistry and Inorganic Chemistry is artificial here, since there is a strong affinity between the second usage under Organic Chemistry and the usage in Inorganic Chemistry. In this case these two divisions (Organic Chemistry, Inorganic Chemistry) can be refactored to these three:

  • Products of hydration reactions
  • Water trapped in crystals -- organic and inorganic
  • Historical usages (in organic chemistry, based on empirical formulas or outdated theories)

Of course the section on clathrate hydrates would remain as it is.

An expert can do this writing better than I can. (And with apter names.) (talk) 20:17, 28 January 2015 (UTC) (talk) 19:52, 28 January 2015 (UTC)

I think you have a valid point that dividing this article into organic and inorganic sections is artificial. Hydrates should really be classified by the state of the water in the compound, rather than by whether or not the compound contains carbon.
So perhaps the first section should be molecules containing H2O as a unit, with subsections for different types of bonding to H2O: coordinative covalent (normally inorgnic), hydrogen bond, clathrate hydrates, etc.
Then a section for molecules containing H and OH separately, with subsections for Products of hydration reactions, and historical usages such as glucose and methanol. Dirac66 (talk) 02:54, 31 January 2015 (UTC)