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16th December 2016 @ 16:07

The idea was that the when we treat the product of our first reaction with four equivalents of hydrazine, the Cl will be cleaved and the hydrazine will be attached giving 6-hydrazineylpyrazine-2-carbohydrazide. Which when treated with KOH can give us Methyl 6-hydrazineylpyrazine-2-carboxylate, where the hydrazine on the side of the carboxylic will be cleaved yielding way for the formation of an ester, which is the third product of our proposed synthesis.



Scheme: /Users/Darshan/Desktop/Screen Shot 2016-12-16 at 2.13.55 AM.png

Table of Reagents (Synthesis of 6-hydrazineylpyrazine-2-carbohydrazide

)

     

Reagent

mass (g)

mols

Molecular Weight (g/mol)

Volume (mL)

Density (g/mL)

6-chloropyrazine-2-carbohydrazide

0.407

0.00236

172.5700

   

Hydrazine Hydrate

 

0.00472

32.0452

0.185

1.020

100% Ethanol

 

0.120

46.0684

7.0

0.789

Product (Synthesis of 6-hydrazineylpyrazine-2-carbohydrazide)

 

0.00236

168.1600

   
 

Theoretical

Percent Yield

 

Actual Yield: 0.162

0.397

40.8%






0.185 ml of (80%) Hydrazine was added.

Sample after hours of reflux.

A, Filtrate of the 6-chloropyrazine-2-carbohydrazide and hydrazine reaction.

B, shows the precipitate of the same reaction.



The Filtrate was then rotovapped, giving a bright orange color.

We couldn’t properly analyze the data for this one  because the NMR was down. However, we leave this project on the verge of a big breakthrough. If our idea of the formation of Methyl 6-hydrazineylpyrazine-2-carboxylate was correct then we’ll have found a way to get to the third product with a good yield and short wait time.

16th December 2016 @ 15:39

Scheme:


/Users/Darshan/Desktop/Screen Shot 2016-12-16 at 2.13.45 AM.png

Table of Reagents (Synthesis of 6-chloropyrazine-2-carbohydrazide)

       

Reagent

mass (g)

mols

Molecular Weight (g/mol)

Volume (mL)

Density (g/mL)

6-chloropyrazine-2-carboxylic acid

0.747

0.00471

158.5400

   

Hydrazine Hydrate

 

0.00471

32.0452

0.185

1.020

100% ethanol

 

0.120

46.0684

7.0

0.789

Product (6-chloropyrazine-2-carbohydrazide)

 

Theoretical Yield: 0.00471

172.5700

   

Actual Yield: 0.623 g

0.813

Percent Yield: 76.6%

     


Synthesis

  1. In a 50 mL round-bottom flask, 0.747 grams of 6-chloropyrazine-2-carboxylic acid and (MW 158.5400g/mol, 4.71 mmol) was combined with 7 mL of ethanol.

  2. 0.185 mL hydrazine hydrate (~80% in H2O) was added dropwise using syringe to the round-bottom flask. The solution started off brown, and gradually turned yellow.

  3. The solution was refluxed for 5 hours.







TLC was run on the product obtained, and it showed that the starting material had been converted to something else. This was a good sign going further into the synthesis.



Left to right, 1st wash, 2nd wash, 3rd wash and 4th wash. We did a TLC test on the four washes. The results were very interesting. 1&2 had a somewhat identical TLC while 3&4 also enjoyed the same relationship at a different rf value from the 1 and 2. A decison was made to mix each of those two together. The reaction was conducted by dividing the whole thing in to three. The precipitate, the 1 & 2, and the 3 & 4. 

bromocresol green data back

bromocresol green data front. 

The data was better visible from the back. Indicated acidity.

GC MS was also run on the system. Our product was supposed to be 6-chloropyrazine-2-carbohydrazide , and as a result we expected the a mass of 172. Only to find a mass of 195. We checked for solvent shifts, but the only legible shift at +23 involved a compound we didn’t so we had to rule out the idea of a contamination. With the help of Rob we came to the conclusion that the we might not have the molecule we thought we had after all.


We then decided to attack the product that we thought was 6-chloropyrazine-2-carbohydrazide with four equivalents of hydrazine.


Attached Files
16th December 2016 @ 12:43

pyrfiltrate (1).pdf
H and C NMR were conducted on the orange precipitate, 6-hydrazinopyridine-2-carbonnitrile.

Data was pretty inconclusive as well as inconsistent so we decided to take the H and C NMR of the precipitate to see incase we had a mixed product.



H NMR literature value

H NMR of the precipitate

δ 8.98

δ 9.23

δ 8.84

δ 9.13

-

δ 7.47


This table is from the many different NMR results obtained for that sample. We found more peaks than we found in the literature value. The GC MS machine was out of order, and in the meantime we set out to do the same for the filtrate. The C NMR also showed a slight difference when comparing to literature values. δ 150, δ 147, δ 130, δ 115,δ  70 and δ  40 for the sample; δ 149, δ 147, δ 147, δ131 and δ 115 for literature value.






11/16/2016

H and C NMR test was run on the filtrate which we  expected to be 6-hydrazinopyridine-2-carboxiamidhydrazide or a mix. We had observed more peaks than expected and that contamination must have occurred.


The results from the H and C NMRs proved to be inconclusive as to what our product was. That made progress at that point impossible. We were forced to stop the current reaction workup, which was a follow up on Ben and Audrey's reaction and attempt the alternative synthesis route we discovered. 

Attached Files
16th December 2016 @ 12:15

 

Name

MW (g/mol)

mmol

Mass(g)

Density

(g/ml)

Voulme

(mL)

6-chloropyrazinecarbonitrile

139g/mol

4.01mmol

0.56g

1.43 g/cm³

/

Ethanol

46.1g/mol

120

/

789 kg/m³

7 mL

Hydrazine hydrate

32.0452 g/mol

4.01 mmol

/

1.02 g/cm³

0.157mL

Product (Unindentified)

?

Theoretical=4.01 mmol

?

?

 



Scheme:

step 1 screen shot.png




Procedure:


  1. In a 50 mL round-bottom flask, 0.56 grams of 6-chloropyrazinecarbonitrile (MW 139g/mol, 4.01 mmol) was combined with 7 mL of ethanol.

  2. 0.157 mL hydrazine hydrate (~80% in H2O) was added dropwise using syringe to the round-bottom flask. The solution started off clear, turned yellow, and then subsequently turned red.

  3. The solution was refluxed for 5 hours.

  4. After allowing to cool to room temperature, vacuum filtration was performed to separate orange precipitate from red filtrate.

  5. Small amount of ethanol was used for wash.

  6. The solvent from filtrate was removed using a rotovap. The orange precipitate was expected to be 6-hydrazinopyridine-2-carbonnitrile while  the filtrate was expected to be 6-hydrazinopyridine-2-carboxiamidhydrazide.

  7. Both were refluxed with 15% aq. KOH for 2 hrs and after cooling there was a work up with dilute HCl and recrystallization from water melted at 250°C  to obtain the same product 6-hydrazinopyridine-2-carboxylic acid.



Smiles

ClC1=CN=CC(C#N)=N1>[H2NH2,H2O]>N#CC2=NC(NN)=CN=C2


HNMR:




TLC: Showed UV activity

S,C & P

S= Starting material

C= Starting + Product

P= product


10% Ethanol 90% Ethylacetate

10% Methanol, 90% EtOH.JPG

The uncrystallized, crystallized and filtered tests showed the same exact value.

RF of S and C = 1

RF of P = 0



1:3 Hexane to ethyl acetate


Crystallized: RF for S&C = 0.72


Filtered: S, S&C = 0.65

Uncrystallized: RF for S&C = 0.56



3:1 Hexane to ethyl acetate


Crystallized: RF for S&C = 0.83



Filtered:S, S&C = 0.90

Uncrystallized: RF for S&C = 0.85



KMnO4 test

This showed us that the product was different from the starting material. We prepared the sample for further analysis.