Indole-3-acetic acid
| Indole-3-acetic acid | |
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2-(1H-indol-3-yl)acetic acid |
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Other names
Indole-3-acetic acid, |
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| Identifiers | |
| CAS number | 87-51-4  |
| PubChem | 802 |
| ChemSpider | 780 |
| DrugBank | DB07950 |
| KEGG | C00954 |
| ChEBI | CHEBI:16411 |
| ChEMBL | CHEMBL82411 |
| Jmol-3D images | Image 1 |
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| Properties | |
| Molecular formula | C10H9NO2 |
| Molar mass | 175.184 |
| Appearance | white solid |
| Melting point |
168-170 °C (441-443 K) |
| Solubility in water | moderate |
 (verify) (what is:  / ?)Except where noted otherwise, data are given for materials in their standard state (at 25 °C, 100 kPa) |
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| Infobox references | |
Indole-3-acetic acid, also known as IAA, is a heterocyclic compound that is a phytohormone called auxin. This colourless solid is native plant compound, potent and the most important auxin.[1] The molecule is derived from indole, containing a carboxymethyl group (acetic acid).
[edit] Biosynthesis and biological activity
IAA is predominantly produced in cells of the apex (bud) and very young leaves of a plant. Plants can synthesize IAA by several independent biosynthetic pathways, four of them starts from tryptophan, but there is also biosynthetic pathway independent of tryptophan.[2] Plants mainly produce IAA from tryptophan through indole-3-pyruvic acid.[3][4] IAA is also produced from tryptophan through indole-3-acetaldoxime in Arabidopsis.[5]
IAA has many different effects, as all auxins do, such as inducing cell elongation and cell division with all subsequent results for plant growth and development. On larger scale, IAA serves as signaling molecule necessary for development of plant organs and coordination of growth.
There are less expensive and metabolically stable synthetic auxin analogs on the market for use in horticulture, such as indole-3-butyric acid (IBA) and 1-naphthaleneacetic acid (NAA).[citation needed]
Studies of IAA in the 1940s led to the development of the phenoxy herbicides 2,4-dichlorophenoxyacetic acid (2,4-D) and 2,4,5-trichlorophenoxyacetic acid (2,4,5-T). Like IBA and NAA, 2,4-D and 2,4,5-T are metabolically and environmentally more stable analogs of IAA. However, when sprayed on broad-leaf dicot plants, they induce rapid, uncontrolled growth, eventually killing them. First introduced in 1946, these herbicides were in widespread use in agriculture by the middle of the 1950s.
[edit] Synthesis
Chemically, it can be synthesized by the reaction of indole with glycolic acid in the presence of base at 250 °C:[6]
Many methods for its synthesis have been developed since its original synthesis from indole-3-acetonitrile.[7]
[edit] References
- ^ Simon, S; Petrášek, P (2011). "Why plants need more than one type of auxin". Plant Science 180 (3): 454–460. doi:10.1016/j.plantsci.2010.12.007. PMID 21421392. http://www.sciencedirect.com/science?_ob=ArticleURL&_udi=B6TBH-51S6X51-2&_user=625101&_coverDate=03%2F31%2F2011&_rdoc=8&_fmt=high&_orig=browse&_origin=browse&_zone=rslt_list_item&_srch=doc-info(%23toc%235143%232011%23998199996%232867740%23FLA%23display%23Volume)&_cdi=5143&_sort=d&_docanchor=&_ct=20&_acct=C000031698&_version=1&_urlVersion=0&_userid=625101&md5=d1409d89eff55b90161ef75e1ff59679&searchtype=a.
- ^ Zhao, Yunde (2010). "Auxin Biosynthesis and Its Role in Plant Development". Annual Reviews of Plant Biology 61: 49–64. doi:10.1146/annurev-arplant-042809-112308.
- ^ Mashiguchi K, et al. (2011). "The main auxin biosynthesis pathway in Arabidopsis". Proc. Natl. Acad. Sci. U.S.A. 108 (45): 18512–18517. doi:10.1073/pnas.1108434108. PMC 3215075. PMID 22025724. http://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=3215075.
- ^ Won C, et al. (2011). "Conversion of tryptophan to indole-3-acetic acid by TRYPTOPHAN AMINOTRANSFERASES OF ARABIDOPSIS and YUCCAs in Arabidopsis". Proc. Natl. Acad. Sci. U.S.A. 108 (45): 18518–18523. doi:10.1073/pnas.1108436108. PMC 3215067. PMID 22025721. http://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=3215067.
- ^ Sugawara S, et al. (2009). "Biochemical analyses of indole-3-acetaldoxime-dependent auxin biosynthesis in Arabidopsis". Proc. Natl. Acad. Sci. U.S.A. 106 (13): 5430–5435. doi:10.1073/pnas.0811226106. PMC 2664063. PMID 19279202. http://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=2664063.
- ^ Herbert E. Johnson and Donald G. Crosby (1973), "Indole-3-acetic Acid", Org. Synth., http://www.orgsyn.org/orgsyn/orgsyn/prepContent.asp?prep=CV5P0654; Coll. Vol. 5: 654
- ^ R. Majima and T. Hoshino (1925). "Synthetische Versuche in der Indol-Gruppe, VI.: Eine neue Synthese von beta-Indolyl-alkylaminen". Berichte der deutschen chemischen Gesellschaft 58 (9): 2042. doi:10.1002/cber.19250580917.
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