Grignard Reaction Lab Report

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Abstract: The Grignard reaction was successfully accomplished. An amount of 1.20 ml of 2-methyl-2-pentanol was collected, and 9.60% yield was calculated based on the theoretical yield. Despite the low amount of 2-methyl-2-pentanol, its identity was confirmed by comparing the experimental refractive index and infrared spectrum to the literature refractive index and infrared spectrum of 2-methyl-2-pentanol.

Statement and purpose
The purpose of this experiment is to synthesize a specific alcohol by using the Grignard reaction. The product is then determined by spectral and physical properties.
Introduction
The Grignard reaction is one of the most important reactions in organic chemistry. The reaction involves the Grignard reagent, which is formed
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An amount of 1.20 ml of the alcohol product was measured and the mol of the product was calculated to be 0.00951 mol. Compared to the theoretical value, the amount of the experimental product was rather very low, 1.20ml (experiment) vs 12.5ml (theoretical). The % yield of the product was calculated to be 9.60%. The reason why the result was dramatically low was due to the fact that multiple of trials were performed. The ether layer was transferred between trials causing it to evaporate off and carry some of the alcohol vapor with it. Multiple trials were carried out because the wrong method of distillation was used. At the first trial, simple distillation was used and the result wasn’t as expected. The boiling point of the alcohol product wasn’t the boiling point of the expected alcohol 2-methyl-2-pentanol. The boiling point of 2-methyl-2-pentanol is 120-122oC (ref.6); however, the boiling point of the alcohol product was about 76-80oC. Simple distillation is useful if the difference between 2 products boiling point is more than 100oC; however, the difference of boiling point between ether and 2-methyl-2-pentanol is less than 100oC, so this method cannot be used. Therefore, when the ether was distilled off, the alcohol vapor was carried over by ether vapor causing the lowered reading of the thermometer. After the ether layer solution was transferred over …show more content…
The theoretical yield of 2-methyl-2-pentanol was calculated below:
0.0992 mol ×102.175g / 1 mol × 1ml / 0.81 g = 12.5ml
The % yield was calculated as below:
1.20ml / 12.5ml × 100 = 9.60 %
Conclusion
After the separation of the alcohol from ether layer, despite the fact that multiple of trials were performed, the product was still be separated and taken IR and refractive index. According to the IR and refractive index, the product was confirmed to be the expected product, 2-methyl-2-pentanol. The amount of product was calculated to be 1.20 ml and the % yield of the product was calculated to be 9.60%. The reason the experimental yield and % yield was very low due to the wrong distillation method used and some of the product was evaporated off with the ether during the transfer between

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