Question

Write a chemical reaction to show that the open structure of D-glucose contains the following :  

Five alcohol groups

Answer 1

Acetylation of glucose with acetic anhydride gives glucose pentaacetate which confirms the presence of five -OH groups. Since it exists as a stable compound, five -OH groups should be attached to different carbon atoms. 

\[\begin{array}{cc}
\ce{CHO} \phantom{.........................}\ce{CHO}\phantom{.........................}\\
\phantom{}|\phantom{..............................}|\phantom{............................}\\
\ce{(CHOH)4 + 5 (CH3CH)2O->(CHOCOCH3)4 + 5CH3COOH} \\
\phantom{}|\phantom{.........}\text{Acetic anhydride}\phantom{.....}|\phantom{........}\ce{O}\phantom{..................}\\
\ce{CH2OH}\phantom{........................}|\phantom{........}||\phantom{...................} \\
\text{Glucose} \phantom{........................}\ce{\underset{\text{Glucose Penta acetate}}{CH2O-C-CH3}}\phantom{.............}
\end{array}\]