Properties of caffeine

Caffeine (C8H10N4O2, molar mass of 194.1906 g/mol, also known as 1H-Purine-2,6-dione, 3,7-dihydro-1,3,7-trimethyl- or 1,3,7-trimethyl-2,6-dioxopurine). Caffeine is a methylxanthine alkaloid found in the seeds, nuts, or leaves of a number of plants native to South America and East Asia that is structurally related to adenosine and acts primarily as an adenosine receptor antagonist with psychotropic and anti-inflammatory activities.

Caffeine is found in many commonly consumed foods, including most commonly coffee. Substantive levels of caffeine can also be found in some teas, energy drinks, sodas, and chocolate.

Caffeine is a simple purine base compound and it is a moderately soluble about 2 g/100 mL in water at room temperature. It tastes bitter, white with melting point 235-238°C. Coffee and tea have owed stimulant properties to caffeine, a simple trimethyl purine derivative. It has an imidazole ring fused to a pyrimidine ring and it is aromatic according to huckle’s rule despite of the two carbonyl groups.

Caffeine appears as odorless white powder or white glistening needles, usually melted together. Bitter taste. Solutions in water are neutral to litmus.

It is a stimulant and the form I of caffeine is metastable. This form is only stable at temperatures ranging from 155°C to 237°C. The form II is stable at room conditions, as 20–25°C.
Properties of caffeine