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5222-73-1 - 3,4-Dimethoxy-3-cyclobutene-1,2-dione, 98% - Dimethyl squarate - Squaric acid dimethyl ester - A18186 - Alfa Aesar

A18186 3,4-Dimethoxy-3-cyclobutene-1,2-dione, 98%

CAS Number
Dimethyl squarate
Squaric acid dimethyl ester

Size Price ($) Quantity Availability
1g 46.20
5g 156.00
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3,4-Dimethoxy-3-cyclobutene-1,2-dione, 98%


Chemical Properties

Formula Weight
Melting point
Very soluble in water.


3,4-Dimethoxy-3-cyclobutene-1,2-dione (Dimethyl squarate) finds it uses in the synthesis of chiral squaramides, highly enantioselective catalyst for the Friedel-Crafts reactions of indoles, 3-(hydroxyamino)-4-methoxy-3-cyclobutene-1,2-dione, squarate derivatives of the O-SP-core antigens, methyl squarate derivative of the Ogawa O-SP-core antigen, o-quinodimethanes, benzocyclobutenes, quinones. It is employed as a starting material in the preparation of o-quinodimethanes, benzocyclobutenes, and quinones.


Store away from oxidizing agents. Keep the container tightly closed and place it in a cool, dry and well ventilated condition.

Literature References

Yong Qian.; Gaoyuan Ma.; Aifeng Lv.; Hai-Liang Zhu.; Jing Zhao.; Viresh H Rawal. Squaramide-catalyzed enantioselective Friedel-Crafts reaction of indoles with imines.Chem Commun (Camb).2010,46(17), 3004-3006.

M Burak Onaran.; Anthony B Comeau.; Christopher T Seto. Squaric acid-based peptidic inhibitors of matrix metalloprotease-1.J Org Chem.2005,70(26), 10792-10802.

GHS Hazard and Precautionary Statements

Hazard Statements: H315-H319-H334-H317-H335

Causes skin irritation. Causes serious eye irritation. May cause allergy or asthma symptoms or breathing difficulties if inhaled. May cause an allergic skin reaction. May cause respiratory irritation.

Precautionary Statements: P284-P261-P280a-P305+P351+P338-P405-P501a

Wear respiratory protection. Avoid breathing dust/fume/gas/mist/vapours/spray. Wear protective gloves and eye/face protection. IF IN EYES: Rinse cautiously with water for several minutes. Remove contact lenses, if present and easy to do. Continue rinsing. Store locked up. Dispose of contents/container in accordance with local/regional/national/international regulations.

Other References

Harmonized Tariff Code


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