My watch list  


IUPAC name 2-Amino-2-(hydroxymethyl)propane-1,3-diol
Other names TRIS, Tris, Tris base, Tris buffer,
TrizmaTM, Trisamine, THAM,
Tromethamine, Trometamol, Tromethane
CAS number 77-86-1
RTECS number TY2900000
Molecular formula C4H11NO3
Molar mass 121.14 g mol-1
Appearance White crystalline powder
Melting point

>175-176°C (448-449 K)

Boiling point

219°C (492 K)

Solubility in water 220 g/100 ml (20°C) in water
Acidity (pKa) 8.1
MSDS External MSDS
Main hazards Irritant
NFPA 704
R-phrases R36, R37, R38.
S-phrases S26, S36.
Flash point Non-flammable
Except where noted otherwise, data are given for
materials in their standard state
(at 25 °C, 100 kPa)

Infobox disclaimer and references

Tris is an abbreviation of the organic compound known as trishydroxymethylaminomethane, with the formula (HOCH2)3CNH2. In biochemistry, tris is widely used as a component of buffer solutions, such as in TAE and TBE buffer, especially for solutions of nucleic acids. It is a primary amine and thus undergoes the reactions associated with typical amines, e.g. condenstations with aldehydes.


Buffering features

Tris has a pKa of 8.3 (at 20 °C), which implies that the buffer is effective pH range between 7.0 and 9.2. Being slightly basic, tris forms an effective buffer for slightly basic solutions, which keeps DNA deprotonated and soluble in water. Tris is commonly combined with EDTA to make "TE buffer" for stabilization and storage of DNA. EDTA binds to divalent cations, particularly magnesium (Mg2+). which is a co-factor for many DNA-modifying enzymes.

Buffer details

Because of its widespread use of tris buffers, detailed information on its use is available. Some features:

  • The pKa declines approximately 0.03 units per degree Celsius rise in temperature.
  • Tris reacts strongly with pH electrodes.[citation needed]
  • It is toxic to mammalian cells.


Tris is prepared in two steps from nitromethane via the intermediate (HOCH2)3CNO2 . Reduction of the latter gives tris(hydroxymethyl)aminomethane.[1]

Other uses

Tris is used as an intermediate for the preparation of surface active agents, vulcanization accelerators, and pharmaceuticals, and used as a titrimetric standard.


  1. ^ Sheldon B. Markofsky “Nitro Compounds, Aliphatic” Ullmann's Encyclopedia of Industrial Chemistry 2002 by Wiley-VCH, Wienheim, 2002. DOI: 10.1002/14356007.a17_401.
This article is licensed under the GNU Free Documentation License. It uses material from the Wikipedia article "Tris". A list of authors is available in Wikipedia.
Your browser is not current. Microsoft Internet Explorer 6.0 does not support some functions on Chemie.DE