Synthesis
The aromatic components are derived from phenol, resorcinol or pyrogallol, For phenol, the aldehyde most often used is simply formaldehyde, while larger aldehydes (acetaldehyde, or larger) are generally required in condensation reactions with resorcinol and pyrogallol. The chemical reaction ranks under electrophilic aromatic substitutions followed by an elimination of water and then a second aromatic substitution. The reaction is acid catalysed or base catalysed. Calixarenes are difficult to produce because it is all too easy to end up with complex mixtures of linear and cyclic oligomers with different numbers of repeating units. With finely tuned starting materials and reaction conditions synthesis can also be surprisingly easy. In 2005, research produced a pyrogallolarene by simply mixing a solvent-free dispersion of isovaleraldehyde with pyrogallol and a catalytic amount of p-toluenesulfonic acid in a mortar and pestle. Calixarenes as parent compounds are sparingly soluble and are high melting crystalline solids.
Read more about this topic: Calixarene
Famous quotes containing the word synthesis:
“Our art is the finest, the noblest, the most suggestive, for it is the synthesis of all the arts. Sculpture, painting, literature, elocution, architecture, and music are its natural tools. But while it needs all of those artistic manifestations in order to be its whole self, it asks of its priest or priestess one indispensable virtue: “faith.””
—Sarah Bernhardt (1845–1923)
“The spider-mind acquires a faculty of memory, and, with it, a singular skill of analysis and synthesis, taking apart and putting together in different relations the meshes of its trap. Man had in the beginning no power of analysis or synthesis approaching that of the spider, or even of the honey-bee; but he had acute sensibility to the higher forces.”
—Henry Brooks Adams (1838–1918)
“The invention of photography provided a radically new picture-making process—a process based not on synthesis but on selection. The difference was a basic one. Paintings were made—constructed from a storehouse of traditional schemes and skills and attitudes—but photographs, as the man on the street put, were taken.”
—Jean Szarkowski (b. 1925)