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Diagram of cis-polyisoprene
The image of the repeat unit structure of cis-polyisoprene indicates a carbon atom in the bottom right that only has 3 bonds. Is this correct? A quick image search pulls up two images which contradict this unique carbon. Examples: http://web.tock.com/kalee/chem32/pol/Image11.gif , http://www.physics.ncsu.edu/stxm/polymerspectro/figures/CisPI.gif
These indicate that the repeating unit is uniform over the three displayed in the picture. Can someone verify this?
- It is incorrect. I will bring that to the attention of the gentleman that drew it in the first place.JSR (talk) 17:02, 2 October 2012 (UTC)
Just corrected some major mistakes
This is my first post on wikipedia and I welcome your criticism/comments. I found quite a bit of misinformation in this article since I study isoprene myself.
1. the original writer was apparently confused about isoprene, which specifically refers to 2-methyl-1,3-butadiene, and “isoprenes”, which is a common name for isoprenoids (terpenoids). In my opinion the use of “isoprenes” is imprecise and should not be used in articles. Isoprene is made exclusively in the non-mevalonate pathway (MEP pathway). Its synthesis is not related to mevalonic acid pathway at all and therefore not inhibited by statin but by fosmidomycin, an MEP pathway inhibitor. The statin section should be either taken out altogether, or moved to the terpenoid article.
2. it is okay to say isoprene is a common structure motif, but not okay to say it is a precursor for other isoprenoids. Dimethylallyl diphosphate / isopentenyl diphosphate (isoprene with 2 phosphate groups on) are the precursors for isoprenoids.
3. “In virtually all organisms, isoprene derivatives are synthesized by the HMG-CoA reductase pathway.” This is incorrect. Most plants and bacteria uses MEP pathway + MVA pathway. The author may have referred to a paper published before 1993, the time at which a non-MVA pathway was discovered.
4. Research on isoprene emission from plants and industrial production of isoprene and related products is very active and research articles are abundant. This article was short for such an important topic. I will try to expand it if time permits.
Isoprene emission by plants in nature and industrial isoprene production are two separate topics so I have separated them here. Also I’ve modified the article at some minor points to make it flow better. I will also add most of the citations later on. Please feel free to criticize/comment/request citation.
On a side note, the nomenclature of isoprene/terpene/isoprenoids/terpenoids here is very messed up. In reality, the terms isoprene and terpene are used interchangeably, and isoprenoids and terpenoids are used interchangeably. What makes things complex is that “isoprenes”/ “terpenes” are also used by people to refer to isoprenoids. The terpene article is apparently duplicating this article (they are essentially the same thing). This could be very confusing for people. I think an ultimate solution is to only have two articles, “isoprene” and “isoprenoids”, and then redirect terpene and terpenoids respectively into these two articles; while making clear in the article that “isoprenes” sometimes are used to refer to isoprenoids. I just don’t know how to start such a proposal here.
Maybe a link explaining what those diagrams mean (I think I remember from high school chemistry, but not everyone did high school chemistry) would be good. --Robert Merkel
- If you are asking if we need a large article on chemical nomenclature, we probably do. However that kind of article could reach the size of a small book in no time flat. Most people learn nomenclature as they go because there is too much of it to swallow at once. Someone wanting to track down what those "diagrams mean" might fruitfully be pointed to a pre-college introduction to the subject of organic chemistry. Isaac Asimov, if I recall correctly, has a book covering that kind of thing. Again, that's a huge topic and outside the scope of my interests.
In short, however, the diagram uses a kind of organic chemistry shorthand. The lines represent carbon-carbon bonds, double lines represent double bonds, and the vertices are tetravalent carbon atoms binding covalently. If, by counting, there are fewer than 4 bonds to carbon, you have to assume that there is a carbon-hydrogen linkage (i.e. a C-H bond ). Dwmyers 18:55, 18 Sep 2003 (UTC)
Atmospheric role of isoprene
As isoprene is the most emitted non-methane volatile hydrocarbon in the atmosphere, and as it plays a crucial role in atmospheric chemistry, a separate section on its atmospheric role might be appropriate. —Preceding unsigned comment added by Karlc1980 (talk • contribs) 17:05, 10 May 2010 (UTC)
'About 95% of isoprene production is used to produce cis-1,4-polyisoprene - a synthetic version of natural rubber.
Natural rubber is a polymer of isoprene - most often cis-1,4-polyisoprene...
Unclear. Isn't second 'cis-1,4-polyisoprene' misplaced?
NantucketNoon 15:06, 7 August 2007 (UTC)
Someone needs to check the density of natural rubber. I believe natural rubber density is of the order of 1gm/cc (Powel, P. C., Engineering with Polymers, Chapman & Hall, London, (1983) pg 16. —Preceding unsigned comment added by 184.108.40.206 (talk) 06:11, 31 August 2008 (UTC)
Isoprene is a major source of volatile organics in the atmosphere, which will photo-oxidise to form aerosol particles, but to call it pollution would be quite misleading. —Preceding unsigned comment added by 220.127.116.11 (talk) 10:45, 16 October 2009 (UTC)
This treatment ignores some of the most important aspects of isoprene. It is produced mostly by plants and in absolutely huge amounts. I don't know what happened to earlier information about isoprene but I will try to find time to add the relevant information. I have personally measured that humans make about 4 mg per day but the source is not known. The vast majority of isoprene is made by plants by the NON-mevalonate pathway, the methyl erythritol pathway. The EPA is going to start regulating isoprene as a possible carcinogen. I routinely measure 100 ppb in my breath and almost everyone I have tested has at least 10 ppb in their breath. You can "stomp" environmental impact, but it doesn't change the fact that incredible amounts of isoprene is made, primarily by oak and aspen trees. This isoprene will react with NOx and sunlight to make isoprene. The solution is not to cut down all the oak trees, but rather we learn that there is even more reason to reduce NOx. 18.104.22.168 (talk) 02:29, 17 May 2010 (UTC)Tom Sharkey, Professor and Chair of Biochemistry and Molecular Biology, Michigan State University
Very poorly written
"Isoprene derives from rubber and is mostly a natural substance which dates back to 1500 b.c.e."
What does this even mean? SOME isoprene may derive from rubber, but as mentioned above "It is produced mostly by plants and in absolutely huge amounts". This has been the case since long before 1500 BCE ...
And what is the function of 'and' in the quoted sentence "Isoprene derives from rubber and ..."? It is logically confused.