Diethyl squarate Chemical Properties

Melting point:

13-18 °C

Boiling point:

95 °C0.1 mm Hg(lit.)

Density 

1.15 g/mL at 25 °C(lit.)

refractive index 

n20/D 1.509(lit.)

Flash point:

>230 °F

storage temp. 

2-8°C

form 

Liquid

color 

Clear yellow to light brownish

Water Solubility 

insoluble

BRN 

640626

InChIKey

DFSFLZCLKYZYRD-UHFFFAOYSA-N

CAS DataBase Reference

5231-87-8(CAS DataBase Reference)

NIST Chemistry Reference

3,4-Diethoxy-3-cyclobutene-1,2-dione(5231-87-8)

Safety Information

Hazard Codes 

Xn,Xi

Risk Statements 

36/37/38-42/43

Safety Statements 

7-26-37/39-24-23

WGK Germany 

3

RTECS 

GU1772466

F 

10

Hazard Note 

Irritant

HS Code 

29145090

MSDS

• Language:English Provider:SigmaAldrich
• Language:English Provider:ACROS
• Language:English Provider:ALFA

Diethyl squarate Usage And Synthesis

Chemical Properties

clear yellow to light brownish liquid

Uses

3,4-Dethoxy-3-cyclobutene-1,2-dione is used as a starting material for synthesis of furanones and quinones. It undergoes ethoxy substitution with amines and unsaturated organosilanes.

Uses

Diethyl squarate is an intermediate for pharma products, for photochemicals used in the dry-view process, in synthesis of photosensitive squaraine dyes (eg. laser dyes used in CD-Rom) and as intermediate for functional polymers.

General Description

The reaction of 3,4-diethoxy-3-cyclobutene-1,2-dione (squaric acid diethyl ester) with glycosylamines (formed by reducing oligosaccharides) was studied. The derivatives formed were linked to amino-functionalized lipids, solids or proteins.

Synthesis

1. Squaric acid (1.0023 g) was dissolved in 30 mL of anhydrous ethanol and heated to reflux overnight. After the reaction was completed, the reaction solution was concentrated and purified by fast column chromatography to give 0.7430 g of diethyl ester of squaric acid in 50% yield. 2. The resulting diethyl (ethyl) squarate, 2-aminopyridine (100 mg, 0.588 mmol) and triethylamine (10 drops) were dissolved in dichloromethane (10 mL) and stirred at room temperature overnight. After completion of the reaction, the reaction solution was concentrated under reduced pressure and purified by fast column chromatography (petroleum ether/ethyl acetate, 2:1) to afford compound 6 as a white solid in 73% yield. 3. The NMR data of compound 6 were as follows: 1H NMR (400 MHz, acetone-d6) δ 10.26 (s, 1H), 8.50-8.29 (m, 1H), 7.98-7.78 (m, 1H), 7.68 (d, J = 8.3 Hz, 1H), 7.14 (dd, J = 6.9, 5.3 Hz, 1H), 4.85 (q, J = 7.1 Hz, 2H), 1.48 (t, J = 7.1 Hz, 3H); 13C NMR (100 MHz, acetone-d6) δ 186.42, 180.83, 170.33, 166.86, 152.22, 149.33, 139.43, 120.17, 113.63, 70.65, 16.06.

References

[1] Journal of Materials Chemistry A, 2015, vol. 3, # 6, p. 2883 - 2894
[2] Angewandte Chemie - International Edition, 2017, vol. 56, # 22, p. 6181 - 6186
[3] Angew. Chem., 2017, vol. 129, # 22, p. 6277 - 6282,6
[4] Journal of the Chemical Society, Perkin Transactions 1: Organic and Bio-Organic Chemistry (1972-1999), 1993, # 2, p. 263 - 272
[5] Chemical Communications, 2013, vol. 49, # 89, p. 10465 - 10467

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