Talk:Hydrogenation

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Hydrogenes[edit]

Why is there no mention of Hydrogenes, the ancient greek scientist who first discovered the phenomenon? --Dante Alighieri 09:37 18 Jul 2003 (UTC)

Because noone has written it yet? Why don't you :) Mat-C 12:52, 29 Apr 2004 (UTC)

Margaret Thatcher as a chemist[edit]

Rumour has it that Margaret Thatcher (the English Prime Minister) invented/developed hydrogenated fats in her previous career as a chemist, does anyone have any hard facts on this? Mat-C 12:52, 29 Apr 2004 (UTC)

Well, the first patent on the process as we know it was by the German chemist Wilhelm Normann in 1902, so we know she did not start it. There have been improvements over the years though. I saw some patents mentioned as late as 1959. From the web I see that she worked as a research chemist for about 4 years, 47-51, and one thing she worked on was a process for mixing air into ice cream. It seems unlikely that she made any major contributions to hydrogenation. AJim 04:10, 30 Apr 2004 (UTC)
Yes, it was air into ice-cream. -- The Anome 07:17, 30 Apr 2004 (UTC)
omg don't even tell me she invented hydrogenation. if that was the case i would believe that the devil exists and that thatcher is the incarnation of satan. —The preceding unsigned comment was added by 72.139.207.240 (talk • contribs) .

chinese version link[edit]

the link to the chinese language version directs to http://zh.wikipedia.org/wiki/%E8%84%B1%E6%B0%A2, which is for 脱氢, DEhydrogenation.

shouldn't it be directed to hydrogenation, http://zh.wikipedia.org/wiki/%E6%B0%A2%E5%8C%96, ie, 氢化?—Preceding unsigned comment added by 24.63.106.230 (talk • contribs) June 25, 2006 (UTC) gorganites and gimli —Preceding unsigned comment added by 88.105.236.193 (talk) 20:01, 3 May 2010 (UTC)[reply]

Depending on where equilibrium is, it is the same process. It is reversible. Gah4 (talk) 21:41, 22 July 2021 (UTC)[reply]

partially hydrogenated[edit]

isn't this very bad for the human body?? why don't some one school me in this. i was told that this causes trans fats in food products, is this correct? i was also told that this hydrogenated oil covers the cells,(the fatty acids job), coats it and does not let the good things(vitamins, nutrients)come in the cell and pretty much tells the fatty acids to take a hike, so the fatty acids then go toward the skin like your face, hips, stomach, thighs and anywhere else people tend to gain weight at. the man made hydrogenated oils do not let the good things come in the cell, but yet allow the bad things to come in. thus we have diabetes, heart disease, obesity and all sorts of health issues, all because we want a longer shelf life on a food product, all because we can make more money, that is why people are going so health nutty and buying all organic food, cuz it has fatty acids, like omega 3, which are very good and natural which the body can use and break down. i heard the human body does can not even use or break down this hydrogenated oil. ??? can some one clear this up??? —The preceding unsigned comment was added by 163.181.251.10 (talk • contribs) .

The American Heart website says that full hydrogenation does not produce trans fatty acids [1], and I think that information should be included in the article. 65.222.231.2 (talk) 14:09, 24 June 2008 (UTC)[reply]

  • Consensus is that trans fatty acids are indeed bad for you. See Trans fat#Health effects.
  • I don't think your explanation of the process by which they do harm is correct (but then again, who knows?). Also, you seem to separate everything into neat categories of "good things" and "bad things", when the truth is that too much of anything is bad for you. Example: potassium is an essential mineral, but it's also the main component of lethal injections. —Keenan Pepper 23:13, 8 September 2006 (UTC)[reply]

The "Health implications" section of this article is completely incomplete. Every single statement in that short paragraph relate to trans fats. The implication is that partial hydrogenation by definition produces primarily trans facts. This is incorrect. Refer to the "Further reading" section of this article: Jang ES, Jung MY, Min DB (2005). "Hydrogenation for Low Trans and High Conjugated Fatty Acids". That article discusses a process proving my point. Therefore and in summary, this paragraph should be moved to Trans fat#Health effects in its current state, and new content written addressing the health implications of hydrogenated oils with AND without trans fats. Leafgreen (talk) 19:22, 26 September 2009 (UTC)[reply]

Let's put this in context. I have in front of me 17 different packages of foods by manufacturers such as Kraft, Nestle, McKee and IBC. Each have in the list of ingredients "partially hydrogenated...oil" as the ONLY fat/oil. On every one of the the Nutrition Facts panels, no trans fat is listed. Therefore, these manufacturers are using a type of partially hydrogenated oil that has less than 0.5 grams of trans fat. Is this formulation of partially hydrogenated oil cardiopathic? Leafgreen (talk) 19:22, 26 September 2009 (UTC)[reply]

But how much of that partially hydrogenated stuff is in a serving? I'm looking at a package of cookies that have a serving size of 31 g. The total fat content is only 2g per serving. If something actually had 0.5 g of trans fat (these cookies are listed as having 0 g of trans fat), that would be 25% of the total fat. At these quantities, the numbers are often very misleading. For instance, as I mentioned earlier, these cookies have 2 g of fat (total) per serving. Further reading shows that this is made up of 0 g saturated fat, 0 g of monounsaturated fat and 1 g of polyunsaturated fat. This doesn't add up. Those three numbers are all possible types of fat there are (trans fat being a type of unsaturated fat), but half of the fat is missing. What really needs to happen is that the government needs to make packaging information more reasonable, so that you don't get people thinking that 0 + 0 + 1 = 2. —Preceding unsigned comment added by 67.116.29.174 (talk) 00:33, 28 February 2011 (UTC)[reply]

Hydrogenation vs. Protonation[edit]

What is the difference between hydrogenation and protonation? Is it simply that hydrogenation is the addition of H2 while protonation is the additon of H+? This should be addressed in the article. --Ttownfeen 00:43, 28 February 2007 (UTC)[reply]

  • The answer to your own question is correct and yes this bit of information must be included in the article , consider it done V8rik 22:15, 28 February 2007 (UTC)[reply]

Butter[edit]

I understand that the process for making butter from cream is very different than that for hydrogenating vegetable oils into margarine, but is there any chemical similarity in the result? Can one say that butter is "naturally hydrogenated" to some extent, or is it instead the case that butter's solidity at room temperature is different than margarine's?

(Trying to partially deflate an email that makes out margarine to be the devil. I say it's only a minor demon.) 69.248.200.36 17:26, 19 August 2007 (UTC)[reply]

Hydrogenation is the chemical process of adding H atoms to stuff, converting unsaturated molecules into molecules that are more saturated. Making butter from cream is a physical process that congeals the fat globules (the whiteness of milk or cream) without changing the degree of saturation of these fats. Butterfat in these globules is 65% saturated. Margerine has a lower percentage of saturated fat than does butter.--Smokefoot 00:17, 21 August 2007 (UTC)[reply]

measuring gas used[edit]

Anyone know (or better also have a picture) of the apparatus used to measure the amount of H2 taken up in the reaction? I recall using an apparatus which appeared to be a burette with a pipe connected to a separating funnel full of a coloured liquid and sort of lining up the levels of a liquids in the funnel and the burette and measuring the volume removed (something to do with pressure equalization ... bit of a sketchy description I know! -- Quantockgoblin (talk) 16:55, 28 April 2008 (UTC)[reply]

Hydrogenated protein?[edit]

What is the purpose of hydrogenating protein? I bought some peanuts that have "hydrogenated soy protein" listed as an ingredient. What is the purpose of this?--Hraefen Talk 18:50, 23 June 2008 (UTC)[reply]

There are so few results after searching for "hydrogenated soy protein" in Google Books, Google Scholar, and even Google, that I wonder if this is not a mistake. On the other hand, there are lots of results if you search for "hydrogenated soy oil", which makes sense. --Itub (talk) 08:05, 26 June 2008 (UTC)[reply]

Use of non-SI units[edit]

If possible, it would be nice to get the diagrams on the page to follow a standard format i.e. converting pressures from Pounds per square inch to bar. Does anyone have the source diagrams to alter them? --Dumas 1830 (talk) 16:39, 7 August 2008 (UTC)[reply]

You'd have to contact the people who created the diagrams (or redraw them from scratch). --Itub (talk) 16:50, 7 August 2008 (UTC)[reply]
I am thinking about replacing the figs and omitting units and many details, which would be difficult to understand to the non-specialist and not needed by the specialist. Suggestions are welcome. Compare

with

I need suggestions for finding the chem equations related to trans fats, which is what people are probably seeking here.--Smokefoot (talk) 17:36, 7 August 2008 (UTC)[reply]
The trans fat article has nice figures of oleic acid and its hydrogenation and isomerization (i.e., trans) products, but it doesn't say much about the reaction itself or the catalyst used.
I understand the motivation for removing unnecessary detail from the equations, but perhaps it would be useful to keep a distinction between the hydrogenation reactions that occur at normal pressures and those that require high pressure? There are significant practical differences between hydrogenating something at 1 atm vs doing it at 100 atm! --Itub (talk) 12:05, 8 August 2008 (UTC)[reply]
New tests. Here are the suggested replacements for the hydrogenation reactions in hydrogenation. Comments welcome. I was thinking that there may be too many equations in the current page so I selected some. Questions, did I select good ones, is the layout and content okay?

--Smokefoot (talk) 13:20, 8 August 2008 (UTC)[reply]

Great stuff... If only I could create (easily) chemical diagrams, then I could change the psi to atm or bar without having to ask you people (thanks though!).

Smokefoot, looks like a good selection. --Dumas 1830 (talk) 18:47, 8 August 2008 (UTC)[reply]

There are free chemical drawing programs out there. Here's a review of several free and commercial programs. http://www.cic.klte.hu/~gundat/rajzprogramok/dprog.html Dikbrown (talk) 00:47, 28 February 2011 (UTC)[reply]

Is it possible to hydrogenate solids (like nuts, whole chuncks of pork fat, suet)?[edit]

Can solids ever by hydrogenated? Like, could you ever find whole nuts that have been hydrogenated? How can you tell if pig fat (unrendered lard) that you buy in whole chucks at the meat section in the supermarket is hydrogenated? —Preceding unsigned comment added by Jacktherrr (talk • contribs) 13:58, 22 January 2009 (UTC)[reply]

No, this only works in solution. Cacycle (talk) 14:57, 22 January 2009 (UTC)[reply]
No, it's not possible, because the alkene bond must adsorb on the catalyst surface for the reaction to occur. This is possible only for fluids. Hydrogenation without a catalyst does not occur at reasonable temperatures. As for pig fat, there's no reason to hydrogenate it. Partial hydrogenation is/was used for converting cheaper plant oil (liquid unsaturates) into a more solid saturate/trans-unsaturate mixture to replace the more expensive saturated fats from animal sources, like butter or lard. When you already have expensive solid fat from an animal source, like lard, there's no point in hydrogenating it. --Vuo (talk) 00:07, 23 January 2009 (UTC)[reply]
Lard and butter is usually hydrogenated to extend shelf life and improve texture, hence they also can't be trusted not to contain artificial trans fat anymore. (Just search for hydrogenated lard) Ma770 (talk) 10:57, 6 May 2010 (UTC)[reply]

Electrolytic Hydrogenation[edit]

Electrolytic hydrogenation is commonly done in lab settings. It gets very high yields when converting ketones to 2ndary alcohols, aldehydes to primary alcohols, and alkenes to alkanes. It just uses an iron cathode which also acts as a catalyst and a sacrificial nickel anode. You can view the source here: http://pubs.acs.org/doi/pdf/10.1021/ed081p1350 I'm not sure if it warrants a spot in this article as it may be too specific of a process. Kasooi (talk) 02:05, 19 August 2011 (UTC)[reply]

The image of the hydrogenation reaction[edit]

I just thought I would mention this tiny mistake, sorry for the pedantry: A triacylglycerol containing two linoleate residues and one oleate residue is shown as being partially hydrogenated to a triacylglycerol containing two oleate residues and one stearate residue. However, the picture incorrectly shows a palmitate residue in place of the stearate. I don't know how to edit images, sorry. — Preceding unsigned comment added by 205.250.1.132 (talk) 03:57, 21 June 2014 (UTC)[reply]

Redirections[edit]

I had commented that hydrogenated vegetable oil should point here, rather than to trans fat because I thought it was misleading. On further thought, it should really point to saturated fat. I would guess most people put these terms in from ingredient labels, and they would be best served by being taken to something relevant to their questions. I believe on US labels, simply saying "hydrogenated" means hydrogenated to saturation. — Preceding unsigned comment added by 71.127.245.95 (talk) 12:51, 2 October 2017 (UTC)[reply]

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Corrections made in Table entitled "Substrates for and products of hydrogenation" in same topic (1.3.)[edit]

-1) header of last column : there must be enthalpy of hydrogenation rather than "heat of hydrogenation", since negative values are given, and the fact that C-C double bond hydrogenation is exothermal (as otherwise mentioned in the text) and the well known relation QR(heat of reaction) = - delHR(enthalpy of reaction) ; -2) values in the last column are much too small (or, in other words, much too high in absolute value) or the unit, kcal/mol, is wrong ! If the unit is changed to kJ/mol, the values ranges given in this last column become acceptable. In conclusion I've changed the unit from kcal/mole to kJ/mole and delete all the minus signs (or replace the 4th column header with Enthalpy of hydrogenation), in order to correct the table.


Refs: 1. F. A. Carey, Organic chemistry, McGraw-Hill, 2004, 5ed., p. 233, Table 6.1., where (correctly named) positive values given for "Heat of hydrogenation" are ranging between 136 kJ/mole (32.6 kcal/mole) for ethylene and 110 kJ/mole (26.4 kcal/mole) for 2,3-dimethyl-2-butene.

2. In Tables 10.36 (p.374), 10.37 (p.379) of ref. [4] (Barnicki in Kent Handbook, 12th ed.) quoted for the header of 4th column, the correct unit, kJ/mole, is specified. Unfortunately, in the original reference [4] same misleading naming is used, i.e. "Heat of reaction" instead of Enthalpy of reaction, in Table 10.36 for the (negative) values given for hydrogenation of various functional groups and in Table 10.37 for (positive) values listed for dehydrogenation reactions.

Regards, Liv.Ichimescu (talk) 17:36, 18 February 2018 (UTC)[reply]

I agree there were lots of inconsistencies. The cited ref has negative values (and one was also not transcribed correctly) in units of "kJ/gmole", so your kJ/mol is clearly a correct correction. The cited ref notes that the reaction is "highly exothermic" and in previous and subsequent pages appears to use "ΔHrxn" for this idea. Our heat of reaction points to the ΔH sense also, and specifically identifies "Standard enthalpy of hydrogenation" as a known phrase. DMacks (talk) 21:11, 18 February 2018 (UTC)[reply]
Might have been my fault, but in any case it is great that Ichimescu improved the table! It would be good to have an entry for aromatics, showing the the enthalpy is not three times that of isolated alkenes.--Smokefoot (talk) 21:36, 18 February 2018 (UTC)[reply]

Theory of semihydrogenated state (Horiuti-Polanyi mechanism)[edit]

I would write that the mechanism of hydrogenation of olefins is still unknown. “Contact with a hydrogenation catalyst necessarily causes cis-trans-isomerization, because the isomerization is thermodynamically favorable.” However, according to the literature, the hydrogenation of C=C bond at low temperature is usually a syn-addition (especially on Pt, see for example Samuel Siegel and George S. McCaler, J. Am. Chem. Soc. 1959, 81, 14, 3655–3658). There are at least six other arguments that make the Horiuti-Polanyi mechanism questionable. More details on my website http://cz.9e.cz/cz-9e-cz/hgb/ Note: In my opinion, hydrogenation and isomerization during hydrogenation are probably independent parallel reactions:

File:Http://cz.9e.cz/wp-content/uploads/2020/09/KH1 3.jpg
Two-layer hydrogenation
File:Http://cz.9e.cz/wp-content/uploads/2020/09/KH1 5.jpg
Two-layer isomerization
V.heral (talk) 12:42, 23 June 2021 (UTC)[reply]
I suppose the finest detail isn't understood, but roughly the molecule binds to the catalyst, which opens up the double bond. Then, maybe with hydrogen already on the catalyst surface, hydrogenates the bond. But all chemical reactions are reversible (though some with a high energy barrier). As well as I know it, after binding to the catalyst, it can release without hydrogenation, and often comes off trans. It might even be reversed after one hydrogen is attached. From Le Chatelier's principle, increasing the pressure will move the equilibrium toward hydrogenation, but it also speeds up the process. So, recent technology reduces the amount of trans-fat generated. Maybe better catalysts, too. But before people knew that trans fats were bad, there was no reason to change things. Gah4 (talk) 02:05, 24 June 2021 (UTC)[reply]

only hydrocarbons[edit]

The first paragraph mentions hydrocarbons, but it also can be used to hydrogenate hydrocarbon parts of larger molecules, such as (as we well know) fats. Is there a more general word that can be used? Gah4 (talk) 21:58, 22 July 2021 (UTC)[reply]

syn addition[edit]

There is a question about syn addition. It seems that syn addition is important for cyclic molecules, where it can't rotate around the (single) bond after hydrogenation. As well as I know, that isn't usual in the case of hydrogenated fats, but then this article isn't specific to them. But I think the section mentioning syn addition should also mention that it applies for cyclic molecules. Gah4 (talk) 04:31, 8 February 2022 (UTC)[reply]

"Partially hydrogenated oil" listed at Redirects for discussion[edit]

The redirect Partially hydrogenated oil has been listed at redirects for discussion to determine whether its use and function meets the redirect guidelines. Readers of this page are welcome to comment on this redirect at Wikipedia:Redirects for discussion/Log/2023 August 6 § Partially hydrogenated oil until a consensus is reached. Jay 💬 05:20, 6 August 2023 (UTC)[reply]

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