Kinetics of Mutarotation

By Amatullah Shahid Lab Partners: Lucas Bertolami Zachary Roncallo Kinectics Of Mutarotation Sunday, October 9, 2022 Kinetics of Mutarotation Page 1

Glucose is an enantiomer with the ability to switch between a α and β form while in solution. A polarimeter cell is used to determine the rotation degrees of an optically active molecule. The room temperature was 18.5 °C and the pressure was 763.3 mmHg for the day the experiment was done. This resulted in an average of 3.2773 for the equilibrium constant and a standard deviation of 0.17996. These numbers helped to established the confidence interval at 95%. With these parameters we found that the reaction favored the β formation while the α wasn't as favored. Abstract Wednesday, October 26, 2022 9:09 PM Kinetics of Mutarotation Page 2

Introduction: Glucose is a simple sugar with the chemical formula of C6H12O6. One of the most abundant monosaccharides. Glucose has two forms: an α -glucose and a β -glucose. Optical isomers are a form of stereoisomers that possess the ability to rotate plane polarized light. Optical isomers have the same number of atoms and bonds but have a different arrangement which makes them non- superimposable mirror images. Glucose has the ability to have mutarotation because the α and β are able to interconvert between each other, Mutarotation is the change in optical rotation in equilibrium between two anomers, when corresponding stereocenters interconvert. Optical Rotation is the angle that a plane of polarization is rotated when polarized light passes through a liquid or the solution that is to be used in the experiment. In this experiment, electronic polarimeter will be used to acquire the angle to determine the mutarotation to establish the equilibrium of the α and β forms of glucose. Introduction Wednesday, October 26, 2022 9:09 PM Kinetics of Mutarotation Page 4

Diagram of Polarimeter Friday, October 28, 2022 10:07 AM Kinetics of Mutarotation Page 5

1st Run Time (minutes) α (Ln{(α 0 - α eq )/(α t - α)})/t = k obsd 0 8.091 #DIV/0! 1 7.968 0.031352 2 7.884 0.026671 2nd run Time (minutes) α (Ln{(α 0 - α eq )/(α t - α)})/t = k obsd 0 8.412 1 8.264 0.039127 2 8.135 0.037263 3 8.007 0.036979 4 7.885 0.036729 How to find the concentrations of [A] eq and [B] eq : [α]D T =10(αobsd)/cl 112=10(4.106)/(0.0802g/mLX 10cm)=51.2 1/51.2=0.0195 g/mL 0.0802 g/mL - 0.0195g/mL= 0.0607 Results Table 1 Glucose Weight g [G] g/ml α eq [A] eq [B] eq K eq Averag e Standard Deviation Confidence Interval 1 4.011 0.0802 4.106 0.0195 0.0607 3.1128 3.2773 0.179963 0.17636 2 4.038 0.08076 4.555 0.0177 0.063 3.5607 3 3.994 0.07988 4.305 0.01855 6 0.0613 2 3.305 4 4.013 0.0826 4.131 0.01999 0.0626 3.131 12.4 M HCl not PCA 1.8 mL of HCl to reach 2.32 M Atmospheric pressure 763.3mmHg Temp 18.5 degrees Celsius Results Wednesday, October 26, 2022 9:09 PM Kinetics of Mutarotation Page 7

2 7.884 0.026671 3 7.802 0.025095 4 7.722 0.024292 5 7.643 0.023852 6 7.565 0.023593 7 7.488 0.023439 8 7.412 0.02335 9 7.337 0.023305 10 7.264 0.02326 11 7.191 0.023271 12 7.122 0.023217 13 7.052 0.023238 14 6.983 0.023271 15 6.915 0.023314 16 overnight 4.106 4 7.885 0.036729 5 7.765 0.036724 6 7.651 0.03663 7 7.538 0.036709 8 7.43 0.03673 9 7.325 0.036782 10 7.222 0.036894 11 7.123 0.036978 12 7.027 0.037072 13 6.936 0.037105 14 6.845 0.037238 15 6.759 0.037308 16 overnight 4.555 3rd Run Time (minutes) α (Ln{(α 0 - α eq )/(α t - α)})/t = k obsd 0 8.333 #DIV/0! 1 8.148 0.047017 2 7.986 0.045043 3 7.833 0.04418 4 7.686 0.043775 5 7.546 0.043478 6 7.409 0.04343 7 7.28 0.043289 8 7.154 0.043288 9 7.034 0.043259 10 6.918 0.043277 11 6.809 0.043216 12 6.704 0.043185 13 6.602 0.043205 14 6.505 0.043201 15 6.412 0.0432 16 overnight 4.305 #DIV/0! 4th run Time (minutes) α (Ln{(α 0 - α eq )/(α t - α)})/t = k obsd 0 7.906 #DIV/0! 1 7.731 0.047467 2 7.564 0.047483 3 7.403 0.047666 4 7.249 0.047802 5 7.105 0.047699 6 6.962 0.047962 7 6.83 0.047931 8 6.705 0.047867 9 6.582 0.047989 10 6.466 0.048039 11 6.352 0.048222 12 6.246 0.048279 13 6.144 0.048367 14 6.047 0.04844 15 5.953 0.048564 16 overnight 4.131 #DIV/0! Kinetics of Mutarotation Page 8

Kinetics of Mutarotation Page 10

Confidence Interval for K eq is 95% 3.1128+35607+3.305+3.131 =3.2773 4 Kinetics of Mutarotation Page 11