Talk:Terpene

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Edits
I've made some extensive changes to this article, trying to expand it from the bare bones state that it was in. If anyone has any suggestions for improvement or additional information needed, please let me know and I'll try to add it or feel free to just make the changes. I would like to redo some of the images so that they are presented in a consistent style (I used some images from different articles, using them as place-holders for now.)  The article is still sparse in the later sections, but at least the current article provides a framework for filling in, I think. Edgar181 05:01, 17 December 2005 (UTC)

IPP + DMAPP -> GPP
I would like a tad more information about how isoprenes combine. The diagram of GPP looks like 2 x DMAPP with the PPi thrown away, but the text says it's IPP + DMAPP. If so, the IPP must have isomerized to DMAPP in the reaction (flipping the double bond 'inward'). So for a complete ignoramus like me looking to learn, this explanation is missing an essential step. Isn't it? And where does the spare PPi go, anyway? ~Anon~

Etymology
The 'terp' root of the word... where does that come from? Turtles? I suppose the rings can look sort of turtle-like... but seriously, this is something that I have not been able to find out, even after consulting the multivolume Oxford English Dicionary at school.
 * I don't know for sure, but my guess is that the word terpene is derived from turpentine, which in turn is probably derived from the plant source it was originally produced from. --Ed (Edgar181)
 * Wouldn't turpentine be a derivative from Terpene, as turpentine is made of terpenes?Atebo88 (talk) 05:23, 30 November 2009 (UTC)
 * It's explained under turpentine. 84.227.252.224 (talk) 20:26, 14 October 2014 (UTC)

Alleopathy?
Any discussion about terpenes and their role in possibly alleopathic plants like salvia leucophylla or eucalyptus?

Toxicity?
leathal doses..etc.. —Preceding unsigned comment added by 71.42.147.99 (talk) 08:08, 18 September 2007 (UTC)

Terpene versus terpenoid (isoprenoid)
A brief statement about the differences between terpene and terpendoid would be helpful to me. 67.232.173.26 (talk) 12:15, 26 April 2011 (UTC)IJV

Hop Compunds?
I was reading about beer and noticed that the hops page under "brewing" and the terpene page list different chemicals as the "four major components of hop essential oils". One shows pinene, the other farnesene. I'm not sure if there's a contradiction there, but it should be looked at by someone who knows. Ramireja (talk) 13:52, 6 January 2012 (UTC)

Types
Many of the examples given are terpenoids rather than terpenes (and therefore do not have the molecular formulas given). I doubt all diterpenes have antimicrobial and antiinflammatory activity; this should probably read "Some are known to be antimicrobial and antiinflammatory." In norisoprenoids peroxydases should be peroxidases. Glycosidases would not produce norisoprenoids. 69.72.92.118 (talk) 05:42, 10 September 2014 (UTC)
 * Thanks for your suggestions for correcting and improving this article. The terms "terpene" and "terpenoid" are often used interchangeably.  As this article says, "Some authors will use the term terpene to include all terpenoids".  So in that context I don't see an issue with how the article may conflate the two, but for clarity it is probably better to include the names of the terpenoid subtypes so I have done so.  I agree with you about the statement regarding antimicrobial and antiinflammatory activity and have simply removed it.  I corrected the misspelling of peroxidases.  Finally, the reference given for the statement about glycosidases producing norisoprenoids seems to support the statement.  The abstract says that glycosidase activities increase the levels of C13-norisoprenoids (I don't have access to the full article, only the abstract, so I'm not sure if this is a direct or indirect effect).  -- Ed (Edgar181) 12:42, 10 September 2014 (UTC)

Biosynthesis
"Terpenes are derived biosynthetically from units of isoprene"

I don't think this phrase is entirely accurate because terpenes are not actually built up from isoprene units. This is clarified in the next paragraph where the article talks about biosynthesis from IPP and DMAPP.

I think it should be clarified that the isoprene rule for predicting the structure and that it is not descriptive of the biosynthetic pathway.

For example, it could say: "Terpenes can be viewed as oligomers of five carbon isoprene units, with the formula C5H8" Beanstash (talk) 18:22, 18 September 2014 (UTC)

Aromatic statements doubtful
(1) Were aromatic compounds really named for their strong aromas? The aromaticity article says both a qualified, careful no (at the top) and yes (in the body). The terpene article says yes.

(2) Is it really true that terpenes are often (chemically speaking) aromatic? The aromaticity article says no (at the top), the terpene article says yes (at the top).

(3) Do strong-smelling substances and/or terpenes really have a protective function due to their ability to drive off parasites? The terpene article says yes, but in view of the other doubtful statements about strong aromas, I'd like to see some evidence. 84.227.252.224 (talk) 20:38, 14 October 2014 (UTC)

When organic chemists talk about aromaticity, they are talking about conjugated rings with alternating single and double carbon-carbon bonds. They do not mean to imply odoriferous, a more precise term for the widespread character of terpenes. The important characteristics of 'aromatic' compounds (as used by organic chemists) are their significant absorption in the ultraviolet spectrum and their chemical reactivity. Many polynuclear aromatic compounds (PNAs) are so large that they have little vapor pressure and so have little odor. The word aromatic in this context is a holdover from early chemists' generalizations.

Untitled
I would like to see the difference between cannabis and non cannabis derived terpenes and a break down of their common uses. Mr Terpenes — Preceding unsigned comment added by 2601:6c1:c000:3370:6923:7c0c:e965:a23b (talk • contribs)

What is a terpene
This artyicle says how terpenes are biosynthaszed, but I did not see an explication of what they are. At a minimum I recommend including the statement from the page Category:Terpenes and terpenoids, "A terpene is a naturally occurring hydrocarbon based on combinations of the isoprene unit." I also recommend including a link to this very helpful page, should there be a way to do that Category:Terpenes and terpenoids.

I don't know why this article has so much to say about terpenoids when there is a separate article about them, but if the terpenoid material must stay, I suggest also including the other statement, "Terpenoids are compounds related to terpenes, which may include some oxygen functionality or some rearrangement, however, the two terms are often used interchangeably." Page Notes (talk) 13:10, 15 April 2019 (UTC)

"120 Compounds" needs to be clarified
Are there about 120 compounds found in Cannabis, or 120 terpenes & terpenoids found in Cannabis?

Biosynthesis
Terpenes are a vast and interesting class of compounds. I could write a book on this topic and never need to go into this kind of detail. I think this section is abstracted from someone’s PhD dissertation. It dominates the article with intellectual obtuseness. Really. I’m very much more chemically literate than the average American college science graduate, and this section is non-accessible. It has to go. It could be replaced for the average high school or community college American with a one accessible vernacular paragraph about plant synthesis. To write such a paragraph is a substantially greater challenge than the abstract here. Sbalfour (talk) 21:46, 3 November 2020 (UTC)

The text says: "Terpenes are derived biosynthetically from units of isopentenyl pyrophosphate (IPP)." And this rather complex organic substance IPP magically appears in the water, soil or air? If it doesn't, where does it come from? If plants makes it (dubious), convince me. I'm not a PhD biochemist, but have a decent grasp of organic chemistry. There's a big chunk of stuff (like the most important part of the synthesis) missing here. Sbalfour (talk) 18:47, 6 November 2020 (UTC)

Physical and chemical properties
A large block of info on the general properties of these compounds is missing: i.e. in addition to being smelly and oily generally, they’re highly non-polar liquids at room temperature, so extraction requires petroleum solvents. And they’re often volatile, flammable, toxic, the lighter molecular weight ones may be absorbed thru the skin, and they’re solvents themselves, so how they’re stored and collected needs to be carefully considered. As a practical matter, working with these chemicals requires expertise because they’re not very pleasant, though most of the time we don’t find these outside a chemical laboratory or industrial complex. Turpentine is exemplary of them. Sbalfour (talk) 11:13, 5 November 2020 (UTC)

Cannabinoids
Given there are many thousands of named terpenes and terpenoids and probably millions with substantive industrial and commercial applications, do we really want to emphasize recreational cannabinoids? They’re still strictly illegal in most places. I think this whole rather lengthy paragraph would be better placed in the Cannabis sativa article. It’s a subtle brand of ‘aggrandizing erudition’. Sbalfour (talk) 12:18, 5 November 2020 (UTC)

I don't see why cannabis being "illegal in most places" would make it inherently irrelevant to the article, especially since it's a multibillion-dollar-a-year industry even in the United States alone. I expect cannabis terpenes are the primary terpenes that most non-experts have heard about and the primary terpenes that have been mentioned in the popular press. Therefore, I think it would be odd not to mention cannabis terpenes in an article intended to inform people about terpenes. 2603:8000:D4F0:1D50:8D18:B86D:EFFA:D (talk) 09:39, 11 March 2024 (UTC)
 * I am uncertain what the deal is. One issue is that canabinoids are terpenoids not terpenes, and this article is about the latter.  But casual readers wont know that distinction and will be disappointed.  In any case, I inserted a picture of tetrahydrocannabinol.--Smokefoot (talk) 13:31, 11 March 2024 (UTC)

Terminology
This section seems superfluous, a whole level 2 section for two sentences? Other organic chemical articles don’t have terminology sections. This is interesting footnote type info. There’s already an elaboration of the term “terpenoid” in the lead, so we don’t need it here. Sbalfour (talk) 22:49, 5 November 2020 (UTC)

Isomers
We’ve mentioned beta carotene and α-pinene in the article without any elaboration of what these signify. The isomeric structure of terpenes is evident and prominent, and in various areas like diet and pharmacology, the differences cannot be ignored. I propose some discussion of this on the Structure section. Sbalfour (talk) 14:36, 6 November 2020 (UTC)

Structure and types
This section is more aptly named "Taxonomy". There's little or nothing here about the structure of terpenes, which would include exposition of isomers, cyclic and chain structures, chirality, homology and possibly crystallography. So I think the section should be split off and renamed, and a separate section Structure added. Sbalfour (talk) 19:54, 11 November 2020 (UTC)

Uses from Ullmann
According to Ullmann's "the industrially most important terpenes": --Smokefoot (talk) 23:36, 13 November 2020 (UTC)
 * Myrcene: precursor to resins
 * p-Menthane: precursor to "1-isopropyl-4-methylcyclohexane hydroperoxide" (rad inititor)
 * α-Terpinene, 1,8-Cineole, 3-Carene, pinane, terpinolene: precursors to perfumes or odorants
 * p-Cymene: solvent and perfume precursor, economically noncompetitive precursor to terephthalic acid
 * 2-Pinane hydroperoxide for polymerization of dienes
 * 2-Pinanol: precursor to linalool
 * Camphene: odorant; intermediate to camphor, isobornyl esters, and Toxaphen
 * The most common commercial terpenes are the pinenes and d-limonene. Sbalfour (talk) 19:03, 15 November 2020 (UTC)

Loss of information
Recent changes to the Applications and Physical and chemical properties sections have lost some information. Specifically, turpentine is for all practical (and even laboratory purposes) pinene, with a few percent volatile contaminants, and the original statement noted the constituents. That has been lost - turpentine is not a generic mixture of turpenes. In the other section, the statements on volatility, miscibility and molecular weight versus volatility were lost. Miscibility is a property separate from solubility, as anyone who has tried to rinse away turpentine with water can readily note. Miscibility is about density, whereas solubility is about polarization. I'm rapidly enlarging the section on properties, and expect it to grow by a factor of 10 or even 20, though I'm starting modestly. So loss or compression of information is not the way to go here. Sbalfour (talk) 19:14, 15 November 2020 (UTC)
 * Hi Sbalfour: the main thing is to thank you for taking leadership in upgrading the article. That effort is surely going to help many readers into the future. to help resolve the frustration you are experiencing, I will give my "gut" responses now and then I will take a more careful look.


 * gut reaction.
 * "Specifically, turpentine is for all practical (and even laboratory purposes) pinene, with a few percent volatile contaminants, and the original statement noted the constituents. That has been lost - turpentine is not a generic mixture of turpenes." Depends on the turpentine one is using, but good point. The other thing about turpentine is that it is chump change in terms of use, as I tried to re-emphasize in that article.
 * your understanding of miscibility vs solubility are incorrect. They are the same thing for the purposes of this article and our readers. Also, terpenes are colorless.  Of course they are flammable.  The info conveyed in this section is fine.  These things are just C10-C15-C20 generic organic compounds, property wise.  Fairly unreactive.  Fairly inconsequential commercially.
 * the biosynthesis section needs help. Fewer short sections.  Ditch the idea that isoprene has anything to do with terpenes. The connection to rosin acids, tall oil, and related exudates is probably something readers are seeking. Cheers,--Smokefoot (talk) 20:21, 15 November 2020 (UTC)

Glad to have some help. I’m not a chemist, but have reasonable general chemistry background. I probably wouldn’t blow up a lab. We’re creeping into the general area of chirality and isomerization in two different sections, and yah, it’s both complex and rather vital. And yes, I agree the biosynthesis section needs a little reorg, and I’m worried about accessibility there. If I can’t understand it with a modest chemical background, the average reader is lost. Sbalfour (talk) 06:50, 16 November 2020 (UTC)

I know isoprene doesn't have anything to do with the chemistry of terpenes, and I didn’t introduce the precept, someone else sourced it, probably from an elementary text. And calling isoprene a “hemiterpene” is belaboring the point. I like the idea that terpenes are bundles of C5H8 units, though they don’t decompose that way and you don’t build anything starting with isoprene. I’ll see if I can backtrack on it.Sbalfour (talk) 07:17, 16 November 2020 (UTC)
 * Sbalfour it is great to have this article edited by experienced editor who is not necessarily card-carrying super-chemist. The result will be more readable and touch on topics that elude chemists perhaps. The Chemistry Project here is fairly active, so any real big problems will be addressed.  Just push back when needed. And feel free to ask for help.--Smokefoot (talk) 21:24, 16 November 2020 (UTC)
 * The lede has been rewritten, and to substantive improvement. I am a scientist, a computer scientist if it matters. My intention as a senior editor is to make articles accessible and sensible to most readers, whom I take as scientifically naive (correct me here). The lede, as another wiser editor than myself, once pontificated, is introduced by a sentence structured as (if "foo" is the title of the article) "a foo is a bar baz quux". So, if I run into a "foo", I have no doubt that I saw a "foo" because "bar baz and quux" are familiar to me in my lived experience. What's a terpene? Precious few will understand any chemical formula, or know that it's (C5H8)n. "Natural product" today means gluten-free flour. So, is a terpene more like wood chips, petroleum, or methane gas, all natural products?  If I run into one, what do I experience? That usually comes down to see, hear, feel, taste and smell. "A terpene is an oily, smelly volatile liquid hydrocarbon produced by plants". Someone with a high school education can readily understand that. Smelly isn't a technical term, but "aromatic" in the technical sense isn't strictly true with respect to terpenes, though its vernacular definition is, and it's better encyclopedic diction. It's not everything you need to know: heptane fits the description but is not a terpene. That's where we need a more precise chemical definition, and that's possibly the second sentence. If one should get so unlucky, one may discover that terpines are also quite flammable, and that's worth mentioning for anyone handling a can of turpentine.  So, I'm proposing replacing the opening sentence of the lede, to increase accessibility. Sbalfour (talk) 18:06, 26 November 2020 (UTC)
 * What's a terpene? Precious few will understand any chemical formula, or know that it's (C5H8)n. Yes, very good point but I dont buy it. Look at amino acid (a more important topic).  Readers are free to ignore the formula and keep reading.  It seems to be asking a lot that readers of terpene will be able to smoothly digest every single point in the intro to a technical topic.
 * "Natural product" today means gluten-free flour. Maybe in your commune, but not if one clicks natural product, one is immediately confronted by a terpenoid. Can't we assume that the reader knows that reading Wikipedia requires use of links. Or maybe you can take your attention to that article.
 * "A terpene is an oily, smelly volatile liquid hydrocarbon produced by plants". good idea
 * heptane fits the description but is not a terpene. Heptane is odorless, or nearly so

In any case, take a try. Big articles take effort. Thanks for the robust feedback. Best wishes, --Smokefoot (talk) 19:31, 26 November 2020 (UTC)
 * terpines are also quite flammable, and that's worth mentioning for anyone handling a can of turpentine. Cars are made of metal, shouldnt that article mention that? Name a hydrocarbon that is not flammable?

Confusing statement
The second sentence of the Biosynthesis section reads "The isoprene units are provided from isoprenyl pyrophosphate and dimethylallyl pyrophosphate, which exist in equilibrium." But according to the article to which both those links lead, they are two names for the same substance. Maproom (talk) 22:20, 26 November 2020 (UTC)
 * Well that's a problem. Probably my fault.  A quick check suggests that the two species in equilibrium are isoprenyl pyrophosphate and isopentenyl pyrophosphate.  BTW, you are invited to look over what we have so far.  I redrafted a lot of the first half but another highly experienced editor thinks that the lede especially is too technical and missing info that would be relevant to an nonexpert.--Smokefoot (talk) 23:49, 26 November 2020 (UTC)

Cannabis and Terpenes
I'm not sure what verbose paragraph mentioned above was removed, but the total absence of any mention of the cannabis plant seems like a flaw in this article. Terpenes are (I believe; I'll do the research unless it becomes clear that my change will be reverted) a major component of the effect of cannabis (that is, THC + different native cannabis terpenes can have significantly different psychological effects on humans). Since marijuana is becoming increasingly legal at the state level in the US (and has been effectively legal in Holland and India (a few governmental bhang shops) for a few decades), that seems to be a non-objection. As such, a sentence or two in the "Biological Function" or "Applications" section seems appropriate. Terpenes might (I don't know) even be relevant to the medical uses of cannabis; that would be another relevant area of research.

There are people (such as me) who will do a Wikipedia search on "terpene" to understand their role in the effects of cannabis. It is a reasonable question, and the current article provides *no* relevant information (or any link to a relevant Wikipedia cannabis article).

Thoughts/comments? Finney1234 (talk) 02:13, 21 August 2021 (UTC)
 * You are probably correct that cannibis users will be expecting/hoping that Wikipedia offers some info relevant to the effects or at least the basic chem of that plant. I am pretty sure that the cannabinoids are all terpenoids (modified terpenes, usually O-containing), not terpenes (contain only C and H).  A number of articles exist on cannabinoids, including THC etc.  Not sure if those articles are very good. --Smokefoot (talk) 03:16, 21 August 2021 (UTC)


 * Thanks, Smokefoot, that gives me some good context (I'm not a chemist, though I do have some knowledge of psychopharmacology). I'll look into it. However, if you're correct, it still might be useful to put in (somewhere) a clarificatory comment that cannabis does *not* actually contain terpenes, and add a reference to another relevant article.Finney1234 (talk) 03:32, 21 August 2021 (UTC)


 * FYI, Smokefoot, I just checked with a friend who *is* a chemist and knows this area well, and some of the significant psychologically effective components in cannabis *are* terpenes. Others are terpenoids, while THC and CBD themselves are cannabinoids but (I believe) not terpenoids. Unfortunately, a number of research articles use the term "terpenoid" as a lump term when they're actually referring to terpenes. So I'll find some references and plan on adding a sentence or two. Finney1234 (talk) 04:08, 21 August 2021 (UTC)
 * You are correct that people are sloppy when distinguishing terpenes from terpenoids. Your friend is mistaken: terpenes are hydrocarbons, a class of compounds with minimal biochemical effects.  It would be awkward to include a comment in the terpene article that "hey if youre looking for info on marijuana, this is not the place, ...".  Otherwise many articles get gummed up with editors second guessing bad search terms.  This will sound prissy, but if someone wants to know more about what's in their cannibis, they need to know some organic chemistry. --Smokefoot (talk) 15:12, 21 August 2021 (UTC)
 * Actually, current research is showing that the terpenes (e.g, myrcene, beta-caryophylene: these are terpenes in the strict sense, correct?) have a significant effect on the way the main psychoactive substance (THC) has psychological (and possibly medical) effects.  Although the terpenes have been shown not to act through the CB1 and CB2 receptors. The reference might require a primary (rather than secondary) source from a high-level peer reviewed journal, but the Terpene article already  seems to use a lot of primary sources anyway (would you agree?). So that is the sentence (or possibly two) that I will add; the "Biological functions" seems to be the most likely location. Thoughts/comments?  (BTW, thanks very much for the interaction and info). Finney1234 (talk) 16:11, 21 August 2021 (UTC)
 * You do what you need to do. I am not in control of this website, I was just offering my views.  Yes, lots of primary sources in all the chem articles.
 * For what its worth, many people are so desperate to find effects of every chemical that of course the terpenes (yes) myrcene and caryophylene show some response, which probably scales with molecular weight and complexity. I mean, we can detect the odor of pentane, so even that bland species interacts with olfactory receptors.  In the end, the question is of significance. In these situations, many folks have their minds made up and will find sources, often narrow, ot ccurrent research" (WP:NOTNEWS) that support their preconceived notions. Not evilness, or even partially evil, but a question of WP:UNDUE.  But like I said, I am prissy.--Smokefoot (talk) 16:29, 21 August 2021 (UTC)
 * Smokefoot You and I obviously have somewhat different perspectives on this (although "prissy" isn't the word I would have chosen). Given that many folks (I was one!) will go to the Terpene page to try to learn *something* about this topic, I think the planned modification is actually important for the quality/usefulness of the article (e.g., the first 10 results of a google search on "terpene" shows up 9 links on cannabis, plus this Wikipedia article). And the terpene research seems pretty solid, at least for early steps on a complex topic.
 * I do know it's not "your" article (WP:OWN), but I still very much appreciate your perspective, comments, and assistance on the topic (as well as your straightforward answers to my questions). In general, I think it's important to try to stick closely to the general approach of a good article (and I'm a big fan of truth and facts). Your comments will greatly improve the planned (potentially controversial) change. Finney1234 (talk) 17:03, 21 August 2021 (UTC)

Cannabis and Terpenes (2)
Not totally surprisingly, some deletions have occurred on the cannabis paragraph in the Terpene article.

1. I consider it important that cannabis be referenced in this article; cannabis is one of the most frequent topics invoked by "terpenes" (do a Google search). Someone who looks up "terpene" for that common reason needs to have some factual information provided.

2. Ferber et al. (2020) is a review article, with 107 primary sources.

3. The 2017 Russo & Marcu review article contains a summary (200 primary sources) of experimentation related to the "entourage" effect. The quote added by 72.249.250.57 is in the abstract of the article, but a (careful) read of the (technical) article shows that that quoted sentence is necessarily based on in-vitro and animal studies, as there are virtually *no* clinical experiments on humans (which is what the original sentence referred to). E.g., Russo's "Conclusion" states "Clinical trials that examine synergistic effects of cannabinoid components are sorely needed". So, currently, it is not known whether the hypothesis is true or false in humans.

4. The widely hypothesized effect of terpenes on cannabinoids is definitely an "application" in the cannabis growth and edibles industry. Again, do a Google search. Finney1234 (talk) 21:15, 5 October 2021 (UTC)

The lede
About a year ago, the lede was fuller, and much more informative. We've lost about 80-90% of it, and I don't know why. Here's what was there:

Terpenes are a large and diverse class of hydrocarbons, produced by a variety of plants, particularly conifers, and by some insects. They often have a strong odor and may protect their hosts by deterring herbivores and by attracting predators and parasites of herbivores.

Terpenes are the major components of rosin and of turpentine produced from resin. They and their derivatives are the primary constituents of the essential oils of many types of plants and flowers. Essential oils are used widely as fragrances in perfumery and traditional medicine, such as aromatherapy.

Terpenes are also major biosynthetic building blocks. Steroids, for example, are derivatives of the triterpene squalene. Synthetic variations and derivatives of natural terpenes also greatly expand the variety of aromas used in perfumery and flavors used in food additives. Alkaloids are obtained by substituting nitrogen atoms for one or more carbon atoms in a terpene.

Extraction of terpenes from plants directly is tedious and labor intensive, so modern industrial processes are used to synthesize them from petrochemicals and byproducts of paper pulp manufacturing.

Terpenes may be conceptualized as consisting of building blocks called isoprenes. The simplest terpene is a pair of isoprenes with formula C10H16. One such simple terpene is pinene, a component of cannabis extracts with a pine forest scent.

"Terpene" is often used interchangeably to refer to the larger class "terpenoid" obtained by substituting (usually oxygen-containing) functional groups for some of the hydrogens in a terpene. Particularly, terpene is often used broadly to refer to terpene alcohols such as linalool.

The current lede is patently deficient, since it does not summarize any part of the article or major sections. Maybe the old lede had deficiencies, but I think it plausible when the current one isn't. I propose replacing the current lede with the old one, and if anyone objects, state exactly what is missing or inaccurate, and let's move to improve it.

Sbalfour (talk) 23:40, 4 April 2022 (UTC)
 * Good idea to have a discussion. I kinda like the current concise lede, which flows well vs the staccato of the factoids above.  Two specific issues:


 * My guess is that this statement is incorrect or misleading "Extraction of terpenes from plants directly is tedious and labor intensive, so modern industrial processes are used to synthesize them from petrochemicals and byproducts of paper pulp manufacturing." The tall oil business is large.
 * The text said extraction from plants is "problemmatical". That's rather vague, but the underlying reason is, it is much more cost effective to refine them from existing large quantities of oil than go find, cut down and process the large number of plants/trees required. Maybe reword? Sbalfour (talk) 16:27, 5 April 2022 (UTC)


 * Resin vs rosin. Rosin, as I recall is gooey stuff from trees (mostly terpenoids) but resin has a broader meaning.--Smokefoot (talk) 23:53, 4 April 2022 (UTC)
 * Correct - rosin may refer to a number of substances, some of which may contain no terpenes at all. Bad example, replace? Sbalfour (talk) 16:27, 5 April 2022 (UTC)


 * I have a more generic issue with the text and/or lede, which is the focus on isoprene as a constituent unit. Isoprene is not a terpene, nor are terpenes built from "isoprene units" by either plants or industrial processes, nor can terpenes be decomposed in any simple way into isoprene units. Yeh, I got it that one possible structure of C5H8 is isoprene, but it's a weasel-y way to present the chemistry. Sbalfour (talk) 16:27, 5 April 2022 (UTC)
 * Oh, isoprene is the key precursor to all terpenes and terpenoids. So if you dont buy that claim as fact and fundamental, then you probably want to announce your views more broadly to the Chemistry project and sort out our basic agreements. To quote the first line of Ullmann's Encyclopedia "Terpenes are natural products, whose structures are built up from isoprene units."
 * Rosin is terpenoids, its resin that has a fairly generic meaning. Smokefoot (talk) 13:02, 6 April 2022 (UTC)

Also as currently stated (C5H8)n, the definition of terpene in the lede would include isoprene, correct? I'm going to add n > 1 in the definition and if I've missed something, I'm sure someone will edit it out quicker than a reference to the sticky icky. briardew (talk) 14:11, 6 November 2022 (UTC)

Terpenes and Cannabis, once again
I am reinstating the sentence about the "Entourage Effect" theory removed recently (for the 2nd time, arbitrarily) by editor Zefr. This was well established as having MEDRS quality review resources back in October, 2021. The theory that terpenes may alter the psychological effects of cannabis is very widespread (do a Google search on "terpene"; about 5 of the first 10 results will involve this), so it is important to have it mentioned here, and to provide a summary of the current scientific evidence related to it. (It will be interesting to see what future clinical research shows.) Finney1234 (talk) 13:41, 17 July 2022 (UTC)
 * A specific role of terpenes in the psychoactive effect of THC is purely hypothetical and currently impossible to prove in clinical studies, so fails MEDRS. Our article on the entourage effect shows the uncertainty of this concept as only conjecture, as does this review. Google searches are not WP:RS sources. Wait for a comprehensive review in a reputable publication. Zefr (talk) 14:52, 17 July 2022 (UTC)

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The deleted sentence (now removed by a second editor (Smokefoot), so I can't fight it) is the following:

"Terpenes (and terpenoids) are prevalent in cannabis (marijuana) and have been postulated to modulate the medicinal or psychological effects of cannabinoids (e.g., THC or CBD) in humans; this is often referred to as the "entourage effect". However, there is currently minimal human clinical data supporting this hypothesis."

Note that this paragraph, with MEDRS review sources, has existed in the article for 9 months, following earlier discussion with both of the editors involved in the current deletion. As such, the paragraph had effectively reached consensus. The current removal is random.

A Google search on "terpene" clearly demonstrates that their presence in cannabis is one of the dominant topics involving "terpenes". The first 5 links that show up in a Google search all refer to the "entourage effect", the claim that terpenes modify the effects of THC. My attempt to provide scientific data that there is currently *no* human clinical evidence supporting this widespread claim has now been removed. The cannabis industry thanks you for your assistance. Finney1234 (talk) 16:00, 17 July 2022 (UTC)
 * Let's see what or if others say. Within the huge realm of terpene, the cannibis aspect seems minor.  I am sure that the reverse is untrue, within the world of cannibis, terpenes are a big deal, because they are all terpenoids.  Have at it in the cannibis articles.  My apologies for seeming uncooperative.--Smokefoot (talk) 16:40, 17 July 2022 (UTC)


 * I'm not going to do it (I'm into science, not business), but articles like the following about the economics of terpenes and the cannabis industry (potentially in the billions of dollars) might be relevant to this article (e.g., Applications).Finney1234 (talk) 20:47, 17 July 2022 (UTC)
 * https://www.forbes.com/sites/davidcarpenter/2019/05/28/cbd-may-be-all-the-rage-but-cannabis-terpenes-are-about-to-hit-big/?sh=24c3ef5559d3
 * User:Smokefoot: As I wrote before (10 months ago!), cannabinoids (e.g., THC and CBD) are not terpenoids. And Cannabis plants contain a significant number of both terpenes and terpenoids. Basic, straightforward information that I posted here before. Science and facts are good! Finney1234 (talk) 21:58, 17 July 2022 (UTC)

RFC on Cannabis and Terpenes
Should the following two MEDRS referenced sentences ( diff with references) be included in the article?

"Terpenes (and terpenoids) are prevalent in cannabis (marijuana) and have been postulated to modulate the medicinal or psychological effects of cannabinoids (e.g., THC or CBD) in humans; this is often referred to as the "entourage effect". However, there is currently minimal human clinical data supporting this hypothesis." Finney1234 (talk) 14:32, 26 July 2022 (UTC)


 * A Google search on "terpene" demonstrates that the "entourage theory" is *the* current leading result related to this subject. Providing scientific data about this claim is therefore important. As such, the theory should be mentioned in the article, and the (current) lack of scientific basis for it should be clearly stated.


 * After an extensive debate 9 months ago, these two sentences have been in the Terpene article. However, the same two editors involved in that debate recently removed them.  For the most recent talk page discussion, look here (I admit, I got irritated having to go through this *again*). For the discussions from 9 months ago, see this and this. Finney1234 (talk) 14:33, 26 July 2022 (UTC)


 * Oppose - neither of the two proposed sentences is supported by MEDRS. The first sentence is about a postulated theory, which is too undeveloped for inferring medical effects in an encyclopedic article on terpenes. The second sentence is the nail in the coffin for this proposal: no human studies support the concept, let alone a MEDRS review placing it in context of how cannabinoids and terpenes may interact in humans, i.e., insufficient evidence to justify such content in the terpene article. We have an article on the entourage effect for which Finney1234 has made no contributions. A 2020 expert pharmacological review states the entourage effect is only a marketing device for cannabis retail products. Zefr (talk) 15:10, 26 July 2022 (UTC)
 * Oppose I dont get the reasoning for promoting this esoteric effect.  I can see mentioning (only) cannabanoids, but terpenes and terpenoids are a large classes of natural products, that include many truly important and more pervasive compounds.  Carotenes.  Many fragrances. Pinene.  We dont give biosynthesis of those things so why should this article be pushing one particular set of compounds?  Just seems like WP:UNDUE to me. Distortion of reality.   --Smokefoot (talk) 02:16, 27 July 2022 (UTC)
 * Oppose This is an article about a whole class of compounds. If and when we have a MEDRS-compliant source that says something interesting, it will be for an individual compound or well-defined small set of compounds. Then the information can be added to the specific article(s) on the compound(s). Mike Turnbull (talk) 13:41, 18 August 2022 (UTC)