Dissolve Cotton

Cellulose is immune to many well-known solvents like acetone or diluted acids. Using Schweizer’s Reagent we will be able to dissolve and reform Cellulose. 

Key Takeaways

  • Schweizer’s reagent is the chemical complex tetraamminediaquacopper dihydroxide, [Cu(NH3)4(H2O)2](OH)2

    Schweizer’s reagent forms a cellulose-copper complex, which is soluble in water

    Acids will destroy the complex and release cellulose again

What chemicals will dissolve Cotton

First, we have to prepare Schweizer’s Reagent and then we’ll dissolve cotton in it.

How to dissolve Cellulose or Cotton

  1. Make a copper hydroxide solution using the 1.6g NaOH and add it to water with 5g copper (II) sulfate pentahydrate dissolved. Copper hydroxide will precipitate. Collect this precipitate by filtration or wait for the precipitate to settle and decant the liquid.

  2. Add 200mL of ammonium hydroxide to the copper hydroxide. The solution will become a dark blue color.

  3. Slowly add the cotton and stir it occasionally. Once the cotton is fully dissolved, it can be sucked up with a pipette.

  4. To reconstitute the fiber, inject the dissolved cotton in a 10% acid solution. The fiber will then precipitate.

How Schweizer’s Reagent works

Cellulose is water-insoluble because it forms strong inter-molecular bonds (hydrogen bonds). Together, single molecules form a big, crystal-like structure. Water can penetrate through cellulose but is not able to dissolve it.

Schweizer’s reagent is the chemical complex tetraamminediaquacopper dihydroxide, [Cu(NH3)4(H2O)2](OH)2. It dissolves the cellulose, forming an intermediate copper-cellulose complex.

When dissolved cotton is added to an acid bath, the cellulose-copper complex is destroyed and cellulose fiber precipitates.

Experiment Video