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In 1871 he discovered the synthesis of phenolphthalein by condensation of phthalic anhydride with two equivalents of phenol under acidic conditions (hence the name). That same year he was the first to obtain synthetic fluorescein , a fluorophore pigment which is similar to naturally occurring pyoverdin that is synthesised by microorganisms (e.g ...
Phenolphthalein is slightly soluble in water and usually is dissolved in alcohols in experiments. It is a weak acid, which can lose H + ions in solution. The nonionized phenolphthalein molecule is colorless and the double deprotonated phenolphthalein ion is fuchsia. Further proton loss in higher pH occurs slowly and leads to a colorless form.
Phenolphthalein can be synthesized by the condensation of phthalic anhydride with two equivalents of phenol under acidic conditions (hence the name). It was discovered in 1871 by Adolf von Baeyer . [ 8 ] [ 9 ] [ 10 ]
Strong bases hydrolyze in water almost completely, resulting in the leveling effect." [7] In this process, the water molecule combines with a strong base, due to the water's amphoteric ability; and, a hydroxide ion is released. [7] Very strong bases can even deprotonate very weakly acidic C–H groups in the absence of water.
In a pH range of about 0-8, the molecule has three aromatic rings all bonded to a tetrahedral sp 3 hybridized carbon atom in the middle which does not make the π-bonding in the aromatic rings conjugate. Because of their limited extent, the aromatic rings only absorb light in the ultraviolet region, and so the compound appears colorless in the ...
The best-selling drug in the U.S., Acetaminophen, also known as Paracetamol, is a phenol. There are various classification schemes. [ 15 ] : 2 A commonly used scheme is based on the number of carbons and was devised by Jeffrey Harborne and Simmonds in 1964 and published in 1980: [ 15 ] : 2 [ 16 ]
In coordination with these concepts, in 1833 the French chemist Marc Antoine Auguste Gaudin presented a clear account of Avogadro's hypothesis, [10] regarding atomic weights, by making use of "volume diagrams", which clearly show both semi-correct molecular geometries, such as a linear water molecule, and correct molecular formulas, such as H 2 O:
The distinction is not very clear-cut. For example, in the formation of an ammonium ion from ammonia and hydrogen the ammonia molecule donates a pair of electrons to the proton; [11] the identity of the electrons is lost in the ammonium ion that is formed. Nevertheless, Lewis suggested that an electron-pair donor be classified as a base and an ...