To really evaluate the success of this synthesis, you will need to carefully con

Question

To really evaluate the success of this synthesis, you will need to carefully consider the following; purity, percent yield, melting point behaviour.

To say your experiment was a success and that you have made a reasonable amount of cholesteryl nonanoate, you want to make sure all of these were successful.

Which of the following statements is true?

1- Cholesteryl nonanoate has been successfully prepared if the percent yield is 90%, the melting point was 74-86oC and liquid crystaline behaviour was not observed when preparing a liquid crystal display.

2- Cholesteryl nonanoate has been successfully prepared if the percent yield is 80%, the melting point was 130oC and liquid crystalline behaviour was observed when preparing a liquid crystal display.

3- Cholesteryl nonanoate has been successfully prepared if the percent yield is 60%, the melting point was 72-80oC and liquid crystalline behaviour was observed when preparing a liquid crystal display.

4- Cholesteryl nonanoate has been successfully prepared if the percent yield is 20%, the melting point was 73-75oC and liquid crystalline behaviour was observed when preparing a liquid crystal display.

Explanation / Answer

Cholesteryl nonanoate Melting point is 77 to 82 °C in crystalline state. A substance (solid) containing soluble impurities usually melts at a lower temperature than the pure compound. It can also melt over a wide range of temperatures. This is called the “melting point depression”. In general, the smaller the range of melting temperatures, the higher the purity of the sample.

1- Cholesteryl nonanoate has been successfully prepared if the percent yield is 90%, the melting point was 74-86oC and liquid crystaline behaviour was not observed when preparing a liquid crystal display. - looks good for a reasonable. Hence this is correct answer.

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