Chemistry in service to Mankind

Dyes and Drugs

DyesDyes are the natural or synthetic coloured substances, which are used in imparting colour to textiles, silk, wool, foodstuff, leather etc.Characteristics of dyes: All coloured substances are n...

What is the difference between a dye and a pigment?

Dyes and pigments are the main forms of colourant i.e.to provide colour to materials, whether they are textiles or paints.

While dyes are soluble in mediums like water, pigments a must be converted to a coarser powder after which it is mixed with a dispersing agent before application. Dyes do not scatter light and look transparent.Another difference is thatpigment particles are much larger in composition size.

Polymers

Polymers: A polymer is defined as a macromolecule, formed by the combination of a large number of small molecular units called monomers. Monomers: They are the small molecular weight molecules tha...

NEB 2080/23 Compulsory Nepali Model Question for Class 12

How would you obtain: anisole from phenol?

Dollar Card : WHY, HOW, USE

If you don’t Know, let me tell you that Dollar Card has been in use in Nepal since March 21, 2021. The Nepal Rastra Bank had announced that Nepali Banks can now issue foreign-currency prepaid cards...

Define: a. Perkin's condensationb. Aldol condensationc. Cannizaro reactiond. Benzoin condensation e. Wolf Kishner reactionf. Carbylamine reaction

a. Perkin's condensation:The reaction between an aromatic aldehyde and the anhydride of an aliphatic acid in the presence of sodium salt of the same acid, leading to the formation of an alpha, beta unsaturated acid is called Perkin's reaction. For example, benzaldehyde and acetic anhydride give cinnamic acid.

benzaldehyde + acetic anhydride --CH₃COONA (455K)----> Cinnamic acid + CH₃COOH

b. Aldol Condensation:Aldehydes and Ketones having at least one alpha-hydrogen atom in the presence of...