Aleksandr Pavlovich Dianin (; 20 April 1851 – 6 December 1918) was a Russian

chemist A chemist (from Greek ''chēm(ía)'' alchemy; replacing ''chymist'' from Medieval Latin ''alchemist'') is a graduated scientist trained in the study of chemistry, or an officially enrolled student in the field. Chemists study the composition of ...

from

Saint Petersburg Saint Petersburg, formerly known as Petrograd and later Leningrad, is the List of cities and towns in Russia by population, second-largest city in Russia after Moscow. It is situated on the Neva, River Neva, at the head of the Gulf of Finland ...

. He carried out studies on

phenol Phenol (also known as carbolic acid, phenolic acid, or benzenol) is an aromatic organic compound with the molecular formula . It is a white crystalline solid that is volatile and can catch fire. The molecule consists of a phenyl group () ...

s and discovered a phenol

derivative In mathematics, the derivative is a fundamental tool that quantifies the sensitivity to change of a function's output with respect to its input. The derivative of a function of a single variable at a chosen input value, when it exists, is t ...

now known as

bisphenol A Bisphenol A (BPA) is a chemical compound primarily used in the manufacturing of various plastics. It is a colourless solid which is Solubility, soluble in most common organic solvents, but has very poor solubility in water. BPA is produced on a ...

and the accordingly named Dianin's compound. He was married to the adopted daughter of fellow chemist Alexander Borodin. In 1887, Dianin succeeded his father-in-law as chair of the Chemistry Department at the Imperial Medical-Surgical Academy in St. Petersburg (now the S.M. Kirov Military Medical Academy).

Bisphenol A and Dianin's compound

Dianin's method for preparing

from 1891 remains the most widely-known approach to this important compound, though the method has been refined for industrial-scale synthesis. It involves the catalysed

condensation Condensation is the change of the state of matter from the gas phase into the liquid phase, and is the reverse of vaporization. The word most often refers to the water cycle. It can also be defined as the change in the state of water vapor ...

of a 2:1 mixture of

and

acetone Acetone (2-propanone or dimethyl ketone) is an organic compound with the chemical formula, formula . It is the simplest and smallest ketone (). It is a colorless, highly Volatile organic compound, volatile, and flammable liquid with a charact ...

in the presence of concentrated

hydrochloric acid Hydrochloric acid, also known as muriatic acid or spirits of salt, is an aqueous solution of hydrogen chloride (HCl). It is a colorless solution with a distinctive pungency, pungent smell. It is classified as a acid strength, strong acid. It is ...

sulfuric acid Sulfuric acid (American spelling and the preferred IUPAC name) or sulphuric acid (English in the Commonwealth of Nations, Commonwealth spelling), known in antiquity as oil of vitriol, is a mineral acid composed of the elements sulfur, oxygen, ...

. The reaction proceeds readily at room temperature producing a crude product containing a great variety of side products (including Dianin's compound) in a matter of hours. The overall equation is simple, with water as the only

by-product A by-product or byproduct is a secondary product derived from a production process, manufacturing process or chemical reaction; it is not the primary product or service being produced. A by-product can be useful and marketable or it can be cons ...

Mechanistically, the acid catalyst converts the acetone to a carbenium ion that undergoes an

electrophilic aromatic substitution Electrophilic aromatic substitution (SEAr) is an organic reaction in which an atom that is attached to an aromatic ring, aromatic system (usually hydrogen) is replaced by an electrophile. Some of the most important electrophilic aromatic substitut ...

reaction with the phenol, producing predominantly ''para''-substituted products. A second carbenium species is produced by protonation and loss of the aliphatic

hydroxyl In chemistry, a hydroxy or hydroxyl group is a functional group with the chemical formula and composed of one oxygen atom covalently bonded to one hydrogen atom. In organic chemistry, alcohols and carboxylic acids contain one or more hydroxy ...

group, leading to bisphenol A (4,4'-isopropylidenediphenol) after a second aromatic substitution reaction. The process is not very selective, and a great number of minor products and side reactions are known. Dianin

Side products that are

isomer In chemistry, isomers are molecules or polyatomic ions with identical molecular formula – that is, the same number of atoms of each element (chemistry), element – but distinct arrangements of atoms in space. ''Isomerism'' refers to the exi ...

s of bisphenol A result from the formation of ''ortho''-substituted products, and include the 2,2'- and 2,4'- isomers of isopropylidenediphenol. Other side reactions include the formation of triphenol I, 4,4'-(4-hydroxy-''m''-phenylenediisopropylidene)diphenol, from the attack of a carbenium

electrophile In chemistry, an electrophile is a chemical species that forms bonds with nucleophiles by accepting an electron pair. Because electrophiles accept electrons, they are Lewis acids. Most electrophiles are positively Electric charge, charged, have an ...

on a bisphenol A molecule and the formation of triphenol II, 4,4',4''-(2-methyl-2-pentanyl-4-ylidene)triphenol, when an

elimination reaction An elimination reaction is a type of organic reaction in which two substituents are removed from a molecule in either a one- or two-step mechanism. The one-step mechanism is known as the E2 reaction, and the two-step mechanism is known as the E1 r ...

converts the carbenium to a reactive

olefin In organic chemistry, an alkene, or olefin, is a hydrocarbon containing a carbon–carbon double bond. The double bond may be internal or at the terminal position. Terminal alkenes are also known as α-olefins. The International Union of Pu ...

. Catalysed dimerisation of acetone via an aldol condensation is well known, and yields diacetone alcohol and (by

dehydration In physiology, dehydration is a lack of total body water that disrupts metabolic processes. It occurs when free water loss exceeds intake, often resulting from excessive sweating, health conditions, or inadequate consumption of water. Mild deh ...

) mesityl oxide in both acidic and basic conditions. The ''in situ'' generation of mesityl oxide adds another reactive olefin to the mixture. In cases where an olefinic moiety can interact with a phenolic hydroxyl group (typically as a result of ''ortho''-substitution), rapid

cyclisation A cyclic compound (or ring compound) is a term for a chemical compound, compound in the field of chemistry in which one or more series of atoms in the compound is connected to form a ring (chemistry), ring. Rings may vary in size from three to man ...

reactions producing flavans and chromans occur. This is the source of Dianin's compound in the mixture, and Dianin subsequently demonstrated that the compound can be produced in much greater yield by reacting phenol with mesityl oxide directly. Later work has shown that production of bisphenol A can be made much more selective by using a reaction mixture with a considerable excess of phenol rather than a

stoichiometric Stoichiometry () is the relationships between the masses of reactants and products before, during, and following chemical reactions. Stoichiometry is based on the law of conservation of mass; the total mass of reactants must equal the total m ...

2:1 composition, greatly suppressing side reactions.

Bisphenol A and Dianin's compound

References

Further reading