Lab 20 report PDF

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lab report...

Description

Reaction of Iodoethane with Sodium Saccharin, an Ambident Nucleophile

Exp. No. 20

Date experiment performed: Thursday, Oct 17th, 2019

Date experiment submitted: Thursday, Oct 24th, 2019

Results:

Product

Mass (g)

Sodium saccharin Watch glass

2,053 18,220

Watch glass + ethylsaccharin ethylsaccharin ethylsaccharin theoretical Melting point range:

19,804

Product

1,584 2,112

Start (°C)

End (°C)

81,0 91,6

85,5 180,3

Yellow product White product 1 H NMR: δ (ppm) 8.25-7.6 4.5-4.75 3.7-4 2.7-3.1 1.3-1.7

Hight (cm) 10.77 1.00 4.34 0.82 8.05

Reaction mechanism:

Or

*drawn with ChemSketch program

Split Multi Quartet Quartet Doublet 2 triplets

Possible structure H- benzene CH2O CH2N ? CH3

Calculations: mass of dry product = (Watch glass + dry product)- Watch glass = 19.804-18.220= 1.584g Yield: 2.053g of Sodium saccharin Mol wt= 205.2g/mol Mass/mol wt = 2.053g/205.2g/mol =0.0100 mol 0.0100 mol of Sodium saccharin => 0.0100 mol of ethylsaccharin Mol wt= 211.2g/mol Mol*mol wt= 0.0100mol*211.2g/mol= 2.112g %Yield: theoretical mass = 2.112g experimental mass = 1.584g 1.584/2.112*100= 75% % composition of products: integration N-ethylsaccharin: 4.34 cm O-ethylsaccharin: 1.00 cm Total : 5.34 cm N −ethylsaccharin 4.34 ∗100=81.3 % ∗100= of N-ethylsaccharin 5.34 Total And 100%-81.3%= 18.7% of O-ethylsaccharin

Observations:

Sodium saccharin was a white solid

- N,N-dimethylformamide was a clear liquid - Iodoethane was a yellow liquid The 2.053g of Sodium saccharin dissolved quickly The original solution is clear. After adding the iodomethane the solution turns yellow. We had 2 product, white powder and then yellow clumpy substance.

Discussion: 1

The Objective of the lab to obtain a mix of either or both N- ethylsaccharin and Oethylsaccharin and determine the major and minor compounds. It was done by reacting sodium saccharin and iodoethane, using N-N- dimethylformamde(DMF) as a solvent. This reaction carries out as a nucleophilic substitution. The nucleophile in this reaction can be either oxygen or nitrogen, that’s why the product names start with O and N. DMF is used as the solvent because it lets the nucleophile attack the substrate and increases the rate of the reaction. Heating throughout the reaction ensures that we get the thermodynamic product as the major product. The mixture of sodium saccharin and DMF was kept homogeneous by stirring and heating. After adding the iodoethane, the flask had to be sealed with Parafilm to prevent any evaporating, since the temperature of the solution was very close to the iodoethane’s boiling point of 720°C. By adding water, we took away the polarity of the product and it was no longer soluble in the polar solvent, so it precipitated. We then collect into solid by vacuum filtration. The melting point range the final product was taken to compare with N-ethylsaccharin and Oethylsaccharin melting points (respectively 95 and 211°C). The H NMR spectrum was taken to identify the % composition of each possible products. For the results, we got a final mass of sodium saccharin of 1.584g which Gives us a percent yield of 75%. Since we had two distinctly colored products, we tried to test them separately and for the melting point ranges we had a mostly yellow product that ranged from 81.0 to 85.5°C and a 1 « Introductory organic chemistry 2 Lab manual », CHEM 222, Concordia University, p.55, 23/10/19

mostly white product that ranged from 91.6 to 180.3°C. Considering the products were probably not pure the yellow one was most likely mixed with iodine impurities and the white one was most likely O-ethylsaccharin mixed with N-ethylsaccharin, since it started to melt at a m.p. close to the 95 and finished higher because of the mix with O-ethylsaccharin. In the NMR we identified two important peaks N-ethylsaccharin at 3.7-4ppm integrated at 4.34cm and for O-ethylsaccharin at 4.5-4.75ppm integrated at 1.00cm. Therefore, the final product has a percent composition of 81.3% N-ethylsaccharin and 18.7% O-ethylsaccharin. Some causes of error may have come from the fact that a lot of product remained on the flask after the transfer to vacuum filtration and then on the filtration paper. And also that we seemed to have iodine impurities left. Apart from the final mass of product, the rest of our results or pretty accurate....