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09-06-2016, First step in synthesis of the hetero-oxadiazole, reaction of 2-6 dichloropyrazine with malononitrile, following procedure from Nikishkin et al (2013)
09-11-2016, Work up of the second attempt at step 1
09-23-2016. Step 1 redo, on 5 gram scale
09-24-2016. Work up of 09-23-2016
09-29-2016, work up and purification of [4]
09/28/2016 Step 4, on a larger scale this time. Conversion of methyl 6-chloropyrazine-2-carboxylate [3] to methyl 6-hydrazineylpyrazine-2-carboxylate [4] using hydrazine according to AEW 85-5
10/07/2016 GC mass spec characterization of rxn from [4]->[5]
10/18/16: Trial work up of reaction of 6-chloropyrazinecarbonitrile and hydrazine
10/4/16: Trial of Step 4:Product [4] to Product [5]
10/6/16: Trial Synthesis of 6-hydrazinelypyrazine-2-carbonitrile and from 6- hydrazinelypyrazine-2-carboximidhydrazide from chloropyrazinecarbonitrile
9/12/16 Step 2 in synthesis. Going from [2]->[3]
9/13/16: Work-up of product [3] and TLC plates
9/15/16: Second Synthesis of Methyl 6-chloropyrazine-2-carboxylate [product 3]
9/18/16-9/20/16: Trial Synthesis of Methyl 6-hydrazineylpyrazine-2-carboxylate (Product 4)
9/22/16: Inconclusive Trial Synthesis of Methyl 6-hydrazineylpyrazine-2-carboxylate (Product 4)
9/25/16-9/27/16: Synthesis of Product 3, methyl 6-chloropyrazine-2-carboxylate
9/27/2016 Late Night
9/29/2016 HNMR of product 4, and HNMR of product 4 after D2O exchange 01/10/2016
9/8/16-Continued Synthesis of 2-(6-chloropyrazin-2(1H)-ylidene)malononitrile
CNMR so far
HNMR so far, of all relevant compounds
The Synthetic scheme of Hetero-oxadiazole Synthesis
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8th September 2016 @ 22:16

While our reflux (from 9/6/16) was running (a 20 hour period), one of the septums that was used to close the 3-neck round bottom flask popped off. This was not discovered until the end of the reflux, so the product was dried. We decided to continue the work-up, assuming that the reaction worked, even if it did not go to completion.

Today we began our work-up of  2-(6-chloropyrazin-2(1H)-ylidene)malononitrile from 9/6/16. We also repeated our procedure from 9/6/16 (Nikishkin et al (2013)) to try to obtain a better yield of 2-(6-chloropyrazin-2(1H)-ylidene)malononitrile. See attached file for illustration of the reaction.

Work-up: 15 mL HCl and 80 mL THF were added to our reflux product from 9/6/16. The solution turned from a yellow-brown to red. The mixture was poured into a separatory funnel, which was shaken to separate the organic and aqueous layers. The aqueous layer gathered at the bottom of the funnel and was removed. Volatiles were removed by vacuum. 65 mL of ethyl ether and 65 mL of H2O were added to the solution, which precipitated the product, which we assume is 2-(6-chloropyrazin-2(1H)-ylidene)malononitrile. Vacuum filtration was used to separate our solid product from the solution. The product was light red in color. Next we will use TLC and NMR to determine if the product is indeed 2-(6-chloropyrazin-2(1H)-ylidene)malononitrile.

While the product from 9/6/16 was worked-up, we repeated the same procedure from 9/6/16 (Nikishkin et al (2013). The only differences were that we added THF in increments of 30 mL, 20 mL, 25 mL, and then 5mL when we were dissolving the malononitrile. Also, we used parafilm over the septums and stoppers of our reflux system, so hopefully the system will stay closed for the 20 hour reflux period. 

 

Citations

Nikishkin, Nicolai I. et al. "Pyrazine-Functionalized Calix[4]Arenes: Synthesis By Palladium-Catalyzed Cross-Coupling With Phosphorus Pronucleophiles And Metal Ion Extraction Properties". New J. Chem. 37.2 (2013): 391-402. Web. 4 Sept. 2016. .

Attached Files
step 1.png
Comments
Re: 9/8/16-Continued Synthesis of 2-(6-chloropyrazin-2(1H)-ylidene)malononitrile by Mandrake Fernflower
9th September 2016 @ 01:54
Good stuff but minor problem - the IUPAC name given is wrong - it should be
2-(6‐chloro‐1,2‐dihydropyrazin‐2‐ylidene)propanedinitrile