Indole-3-acetic acid

From Wikipedia, the free encyclopedia

Indole-3-acetic acid

General
Systematic name	1H-indole-3-acetic acid
Other names	indole-3-acetic acid indoleacetic acid heteroauxin IAA
Molecular formula	C₁₀H₉NO₂
SMILES	C1=CC=C2C(=C1)C(=CN2)CC(=O)O
Molar mass	175.18 g/mol
Appearance	White powder (unstable)
CAS number	[87-51-4]
Properties
Density and phase	? g/cm³, ?
Solubility in water	sparingly sol.
Melting point	168-170 °C (441-443 K)
Boiling point	? °C (? K)
Acidity (pK_a)	4.75
Hazards
MSDS	External MSDS
Main hazards	?
NFPA 704
Flash point	171 °C
R/S statement	R: ? S: ?
RTECS number	?
Supplementary data page
Structure and properties	n, ε_r, etc.
Thermodynamic data	Phase behaviour Solid, liquid, gas
Spectral data	UV, IR, NMR, MS
Related compounds
Related compounds	auxin indolebutyric acid 1-naphthaleneacetic acid
Except where noted otherwise, data are given for materials in their standard state (at 25 °C, 100 kPa) Infobox disclaimer and references

Indole-3-acetic acid, also known as IAA, is a member of the group of phytohormones called auxins. IAA is generally considered to be the most important native auxin.

1 Auxin
2 Chemical properties of IAA
3 See also
4 Additional images
5 External links

[edit] Auxin

Main article: Auxin

It is produced in cells in the apex (bud) and young leaves of a plant. Plant cells synthesize IAA from tryptophan. It 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. There are less expensive and more stable synthetic auxin analogs on the market for use in horticulture, such as indole-3-butyric acid (IBA) and 1-naphthaleneacetic acid (NAA).

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 chemically 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] Chemical properties of IAA

IAA can be produced by the reaction of indole with potassium glycolate at 250 C, but this compound is chemically unstable in particular when exposed to light or changing temperature.