[Mimic]

In tea leaves, caffeine is present along with other compounds such as tannins and cellulose. Tannins are a class of compounds forming part of the esters, and by hydrolysis they form the corresponding acid, the gallic acid, and the corresponding phenol, glucose. Cellulose, on the other hand, is a polymer of glucose, practically insoluble in water.
The derivatives of tannins hydrolysis  can be precipitated as little calcium-soluble salts with the addition of CaCO₃. So, gallic acid can be preciptated by the reaction

$$2 \ce{R-COOH + CaCO_{3}}  \rightarrow \ce{(R-COO)_{2}Ca\downarrow + \; CO_{2} + H_{2}O}$$

Glucose can precipitate in the same way? If can do it, what is the reaction?

Thanks in advance

[Borek]

Gallic acid precipitates as a salt, glucose in general is not acidic and doesn't form salts.

[Mimic]

So, glucose will be separated together with the cellulose during the extraction with diethyl ether?

[Arkcon]

In tea leaves, caffeine is present along with other compounds such as tannins and cellulose.

A clear fact, as stated.

Tannins are a class of compounds forming part of the esters, and by hydrolysis they form the corresponding acid, the gallic acid, and the corresponding phenol, glucose.

That is one way to explain the relation between gallic acid and tannins.  But tannins are generally defined as polyphenoic compounds, sometime made up of gallic acid.  https://en.wikipedia.org/wiki/Tannin#Structure_and_classes_of_tannins  I don't know why you mention esters here -- one ester group makes something an ester, but the properties of a large molecule, with meany other groups, isn't the same those of a simple ester.

There's nothing technically wrong with what you've written, but stung together, you may be heading to incorrect conclusions.

https://en.wikipedia.org/wiki/Tannin#Structure_and_classes_of_tannins

Cellulose, on the other hand, is a polymer of glucose, practically insoluble in water.

A clear fact, as stated.

The derivatives of tannins hydrolysis  can be precipitated as little calcium-soluble salts with the addition of CaCO₃. So, gallic acid can be preciptated by the reaction

$$2 \ce{R-COOH + CaCO_{3}}  \rightarrow \ce{(R-COO)_{2}Ca\downarrow + \; CO_{2} + H_{2}O}$$

An interesting fact that I didn't know.

Glucose can precipitate in the same way? If can do it, what is the reaction?

No.  Can you tell us why you think you can?  Do you think you have explained why you think it should be so in this thread?  Because when I split each statement up, you should be able to see there are non sequiturs.