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 74-86^oC 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 130^oC 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 72-80^oC 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 73-75^oC and liquid crystalline behaviour was observed when preparing a liquid crystal display.

Answer 1

Cholesteryl nonanoate is a liquid crystal with melting point in the range of 77 to 82 °C. If the prepared sample is not showing liquid crystal behavior, then the synthesis is unsuccessful

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

Here percent yield is high, but liquid crystalline behavior was not observed. Therefore this is not a successful synthesis

This is not true

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

Here percent yield is good, however melting point was above the melting point of Cholesteryl nonanoate. Therefore this is not a successful synthesis

This is not true

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

Here percent yield is good, liquid crystalline behavior was observed and a range of melting point was comparable to Cholesteryl nonanoate. Therefore this is not a successful synthesis

This is true

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

Here percent yield is very low, liquid crystalline behavior was observed

Therefore this is not a successful synthesis

This is not true

Answer:

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