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12th February 2014 @ 23:56

I am following the method used by Eduvie Omene (Repeat of Synthesis of 6-chloropyrazine-2-carboxylic Acid EO 7-3, Repeat of Synthesis of 6-chloropyrazine-2-carboxylic Acid EO 7-2 and Synthesis of 6-chloropyrazine-2-carboxylic Acid EO 7-1)

Methyl 6-chloro-2-pyrazinecarboxylate (5.70 g, 33 mmol, from IT 3-1) was dissolved in ethanol (80 mL). Sodium hydroxide (80 mL, 160 mmol, 2 M, aq.) was added and the reaction mixture left stirring at room temperature for 2 h. Hydrochloric acid (2 M, aq, ~100 mL) was added until pH 3 was reached. The reaction mixture was diluted with water (480 mL) and extracted into ethyl acetate (4 x 320 mL). The organic extracts were washed with brine (320 mL), dried over magnesium sulfate, filtered and concentrated in vacuo to afford a pale yellow powder of 6-chloropyrazine-2-carboxylic acid (1.45 g, 9.15 mmol, 27.7 %, m.p. 151.7 - 153.3 °C (commercial m.p. 154.8 - 158.2 °C).

The NMR of this product showed the presence of a small amount of impurities (8.3-7.3 ppm). A recrystallisation from hexane was conducted to yield pure 6-chloropyrazine-2-carboxylic acid (0.5950 g, 3.75 mmol, 11.4 %).

Hazard Assessment

Synthesis of IT 4 6-chloropyrazine-2-carboxylic acid.docx

IT 4-1.png

InChI

InChI=1S/C6H5ClN2O2/c1-11-6(10)4-2-8-3-5(7)9-4/h2-3H,1H3

to

InChI=1S/C5H3ClN2O2/c6-4-2-7-1-3(8-4)5(9)10/h1-2H,(H,9,10)

1H NMR (200 mHz, CDCl3)

After column:

H NMR IT 4-1 after column CDCl3.pdf

Commercial 6-chloropyrazine-2-carboxylic acid:

H NMR 6-chloropyrazine-2-carboxylic acid_commercial_CDCl3.pdf

After recrystallisation from hexane:

1H NMR IT 4-1 after recryst ppt CDCl3.pdf

Linked Posts
Attached Files
Synthesis of IT 4-1.png
Synthesis of IT 4 6-chloropyrazine-2-carboxylic acid.docx
IT 4-1.png
H NMR IT 4-1 after column CDCl3.pdf
H NMR 6-chloropyrazine-2-carboxylic acid_commercial_CDCl3.pdf
1H NMR IT 4-1 after recryst ppt CDCl3.pdf
Comments
Re: Synthesis of 6-chloropyrazine-2-carboxylic acid (IT 4-1) by Alice Williamson
13th February 2014 @ 00:30
HIRAC seen and approved.