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27th July 2016 @ 23:56

Procedure:

For details of synthesis of hydrazinylpyrazine, see Synthesis of 2-Chloro-6-hydrazinylpyrazine (AEW 85-7)

Hydrazinylpyrazine can also be purchased commercially.

Hydrazinylpyrazine (8.00g, 55.3mmol, 1 equiv.), triethyl orthoformate (16.40g 18.4 ml, 111 mmol, 2 equiv.), and tosylic acid (1.9g, 11.1mmol, 0.2 equiv.) were dissolved in toluene (158ml, 0.35 M with respect to Hydrazinylpyrazine) and heated at reflux for about 24 hours(using Dean Stark Aparatus to set up)

Volatiles were removed under reduced pressure, remaining orthoester was blown off under a gentle stream of nitrogen.

NMR of the crude showed that purification is needed. TLC showed that 6 fractions were spotted. The reaction mixture was dissolved in ethyl acetate and mixed with slica. The solvent (ethyl acetate) was evaporated under reduced pressure. Purified by column chromatography (30 to 100% ethyl acetate in hexanes). All fractions are yellow solid.

Strings:

ClC1=CN=CC(NN)=N1

and

CCOC(OCC)([H])OCC

to

ClC1=CN=CC2=NN=CN21

InChI=1S/C4H5ClN4/c5-3-1-7-2-4(8-3)9-6/h1-2H,6H2,(H,8,9)  

and  

InChI=1S/C7H16O3/c1-4-8-7(9-5-2)10-6-3/h7H,4-6H2,1-3H3  

to  

InChI=1S/C5H3ClN4/c6-4-1-7-2-5-9-8-3-10(4)5/h1-3H

HIRAC

HM 1-3.docx

Log

28th Jul 

Reaction started at 11:40

 

29th Jul 

There was no liquid collected in Dean Stark aparatus and solvent was not refluxing though the temperature of oil bath was 110℃.TLC was performed, showing SM was consumed and 4 product was formed. 

TLC also showed that there was impurity in SM. So I checked two batches of SM(The previous one and new-made one) by TLC. Both of them had two spots.

 

Reaction was switched of at 1:30. Toluene was removed.

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HM 1-3.docx
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Comments
Re: Synthesis of 5-chloro-[1,2,4]triazolo[4,3-a]pyrazine (HM 1-3) by Alice Williamson
28th July 2016 @ 01:04
HIRAC seen and approved. Discussed use of Dean Stark Apparatus.