Schweizer's reagent is a
metal ammine complex with the formula
salt
In common usage, salt is a mineral composed primarily of sodium chloride (NaCl). When used in food, especially in granulated form, it is more formally called table salt. In the form of a natural crystalline mineral, salt is also known as r ...
consists of tetraamminediaquacopper(II) cations () and hydroxide anions ().
It is prepared by dissolving copper(II) hydroxide in an aqueous solution of ammonia.
It forms an azure solution. Evaporation of these solutions leaves light blue residue of copper hydroxide, reflecting the lability of the copper-ammonia bonding. If conducted under a stream of ammonia, then deep blue needle-like crystals of the tetrammine form. In presence of oxygen, concentrated solutions give rise to
nitrites . The nitrite results from
oxidation
Redox ( , , reduction–oxidation or oxidation–reduction) is a type of chemical reaction in which the oxidation states of the reactants change. Oxidation is the loss of electrons or an increase in the oxidation state, while reduction is ...
of the ammonia.
Reactions with cellulose
Schweizer's reagent was once used in production of
cellulose
Cellulose is an organic compound with the chemical formula, formula , a polysaccharide consisting of a linear chain of several hundred to many thousands of glycosidic bond, β(1→4) linked glucose, D-glucose units. Cellulose is an important s ...
products such as
rayon
Rayon, also called viscose and commercialised in some countries as sabra silk or cactus silk, is a semi-synthetic fiber made from natural sources of regenerated cellulose fiber, cellulose, such as wood and related agricultural products. It has t ...
and
cellophane (see
cupro). Cellulose, which is quite insoluble in water (hence its utility as clothing), dissolves in the presence of Schweizer's reagent. Using the reagent, cellulose can be extracted from wood pulp, cotton fiber, and other natural cellulose sources. Cellulose precipitates when the solution is acidified. It functions by binding to vicinal
diols.
Presently, the reagent is used in the analysis of the
molecular weight
A molecule is a group of two or more atoms that are held together by Force, attractive forces known as chemical bonds; depending on context, the term may or may not include ions that satisfy this criterion. In quantum physics, organic chemi ...
of cellulose samples.
History
These properties of Schweizer's reagent were discovered by the Swiss chemist
Matthias Eduard Schweizer (1818–1860), after whom the reagent is named. The French chemist Louis-Henri Despeissis then proposed a procedure where cellulose is extruded into diluted sulphuric acid. This leads to the complex no longer being stable enough to hold the cellulose in solution and it precipitates out forming strings. These strings were later used in industry to make artificial silk which was called rayon in the US and viscose in the UK. It was also originally used to make cellophane.
See also
*
Tetraamminecopper(II) sulfate
Footnotes
References
*
*{{cite journal, author =George B Kauffman, title = Eduard Schweizer (1818-1860): The Unknown Chemist and His Well-Known Reagent, journal = J. Chem. Educ., year = 1984, volume = 61, issue = 12, pages = 1095–1097, doi = 10.1021/ed061p1095, bibcode = 1984JChEd..61.1095K
Copper complexes
Hydroxides
Ammine complexes
Tetraamminecopper(II) compounds