We do not know why Mr. Robiquet has not published the analysis of coffee which he read to the Pharmacy Society. Its publication would have allowed us to make caffeine better known and give us accurate ideas of coffees composition ...
Robiquet was one of the first to isolate and describe the properties of pure caffeine, whereas Pelletier was the first to perform an elemental analysis.In 1827, M. Oudry isolated "théine" from tea, but in 1838 it was proved by Mulder and by Carl Jobst that theine was actually the same as caffeine. In 1895, German chemist Hermann Emil Fischer (1852–1919) first synthesized caffeine from its chemical components (i.e. a "total synthesis"), and two years later, he also derived the structural formula of the compound. This was part of the work for which Fischer was awarded the Nobel Prize in 1902. Historic regulations
Because it was recognized that coffee contained some compound that acted as a stimulant, first coffee and later also caffeine has sometimes been subject to regulation. For example, in the 16th century Islamists in Mecca and in the Ottoman Empire made coffee illegal for some classes. Charles II of England tried to ban it in 1676, Frederick II of Prussia banned it in 1777, and coffee was banned in Sweden at various times between 1756 and 1823.
This is presumably due to the need for a higher intake to achieve a comparable desired effect, not that the gene led to a disposition for greater incentive of habituation. Chemistry
Pure anhydrous caffeine is a bitter-tasting, white, odorless powder with a melting point of 235–238 °C. Caffeine is moderately soluble in water at room temperature (2 g/100 mL), but very soluble in boiling water (66 g/100 mL). It is also moderately soluble in ethanol (1.5 g/100 mL). It is weakly basic (pKa of conjugate acid = ~0.6) requiring strong acid to protonate it. Caffeine does not contain any stereogenic centers and hence is classified as an achiral molecule.The xanthine core of caffeine contains two fused rings, a pyrimidinedione and imidazole. The pyrimidinedione in turn contains two amide functional groups that exist predominantly in a zwitterionic resonance the location from which the nitrogen atoms are double bonded to their adjacent amide carbons atoms. Hence all six of the atoms within the pyrimidinedione ring system are sp2 hybridized and planar. Therefore, the fused 5,6 ring core of caffeine contains a total of ten pi electrons and hence according to Hückels rule is aromatic. Synthesis
The biosynthesis of caffeine is an example of convergent evolution among different species.Caffeine may be synthesized in the lab starting with dimethylurea and malonic acid.Commercial supplies of caffeine are not usually manufactured synthetically because the chemical is readily available as a byproduct of decaffeination. Decaffeination
Extraction of caffeine from coffee, to produce caffeine and decaffeinated coffee, can be performed using a number of solvents.