# Does glucose react with Brady's reagent?

A couple of reactions of glucose have been a source of great confusion to me. One of them is it's reaction with the Brady's reagent. It's pretty debatable whether the result is positive or negative. Could someone please shed some conclusive light onto this?

Furthermore, Glucose itself successfully produces an oxime with hydroxylamine. In contrast, it's pentaacetate fails to do so. Why does this occur? Why can't the pentaacetate, like glucose, "break out" of it's cyclic form to give a positive hydroxylamine test?

Edit: I found out about the oxime test, I had overlooked the fact that glucose pentaacetate doesn't have any hemiacetal. The Brady's test though, is still open for debate.

• I have found that glucose fails to show the 2,4 DNP test and fails to show nucleophilic addition by sodium bisulphite. Since the cyclic form of glucose is in equilibrium with the open form, I cannot think of any reason why they do not, however. – Charles Aug 28 '15 at 6:38

The reaction of $\ce{NH2OH}$ with an aldehyde or ketone produces an oxime.
$$\ce {R2C=O + NH2OH·HCl + NaOH → R2C=NOH + NaCl + H2O}$$
A positive test is signaled by a yellow, orange or red precipitate (known as a dinitrophenylhydrazone). $$\ce {RR'C=O + C6H3(NO2)2NHNH2 → C6H3(NO2)2NHNCRR' + H2O}$$