Aniline, as important as it is invisible

From the morning run to the moment we go to bed, aniline marks a discreet presence, enabling the existence of a thousand and one products in our daily lives whose function we do not do without.

Shared by many indispensable goods, aniline has particularities that are different from any other product, which make this raw material one of the most important chemicals in our daily lives.

Also known as aminobenzene or phenylamine, it is a substance belonging to the family of primary amines – an important compound in the manufacture of dyes.

Its formula is C₆H₅NH₂ and, in its pure state and under normal conditions of temperature and pressure, it is a colorless and oily liquid. Aniline is obtained by hydrogenation of nitrobenzene and in the presence of a catalyst. It is susceptible to oxidation and, although it has no color, it darkens when exposed to air, even turning yellow or even almost red, which anticipates its propensity for the manufacture of dyes.

To trace the origins of aniline, we have to go back to the 19th century, when it was isolated for the first time in 1826, by Otto Unverdorben, using the process of destructive distillation of indigo vegetable dye. Initially named Crystallin, the synthesis of aniline passed through the hands of several chemists, until 1843, when August Wilhelm von Hofmann demonstrated that it was the same substance, henceforth known as aniline.

Interestingly, the etymology of this name, attributed by Carl Fritzsche, one of the many “discoverers” of aniline, takes us to Portugal, where the word indigo comes from and which refers to the plant also known as indigo, from the Indigofera suffruticosa family.

The first steps towards the integration of aniline in the chemical industry took place in 1856, when William Perkin, a student of von Hofmann, discovered purple aniline while trying to synthesize quinine, opening the door for other dyes derived from aniline to be discovered.

The basis for the presence of aniline in numerous products is the transformation into Methylene Diphenyl Diisocyanate (MDI), which since the 1980s has driven the integration of aniline as an essential substance for the comfort of modern life.

It is using this compound that rigid polyurethane foam is produced, used in the manufacture of rubber, later applied in the soles of shoes, tires and car steering wheels, in foam mattresses and in the insulation of buildings and refrigeration systems.

In the agricultural industry, aniline is used in the manufacture of herbicides and fungicides, essential in the control of pests and weeds. It also allows the manufacture of synthetic dyes, such as indigo, applied in the coloring of jeans, as well as in the production of photographic reagents and stabilizers for the latex industry.

No less relevant is the use of aniline in the manufacture of aramid fibers, which are lightweight products that are highly resistant to heat and shock. These products are the ones chosen by fire brigades and also by military and police forces (such as bulletproof vests) for the most risky interventions.

Bondalti, the largest Portuguese chemical company, is the leader in aniline sales in Europe and one of the world's largest non-integrated producers of this compound.

Production using proprietary technology, resulting in a high quality of the final product, is internationally recognized and the motto for exports to numerous geographies.

The company supplies aniline through pipelines, always respecting the most demanding environmental and safety standards. In Portugal, the Bondalti plant occupies around 3% of the world's installed aniline capacity.

The chemicals that Bondalti produces at its industrial units have a vast field of application, which extend far beyond the manufacture of rubbers and foams. An undeniable truth about aniline – it is an essential good for our daily lives.