In ancient Greece, wounds were flushed with spirits or vinegar. In the 15th century, papal physician Johann Vigo (1460-1520) advocated cauterizing gunshot wounds with scalding oil. For centuries, people disinfected wounds using materials they already had on hand.
That situation did not change until the late 19th and 20th centuries, when scientists gained a clearer understanding of what gave certain substances their disinfecting properties. The realization slowly emerged that the formulation as a whole – and not solely the active agent – was what determined how well a disinfectant really worked.
Depending on the application, formulations are now enhanced with corrosion inhibitors, wetting agents, viscosity and pH stabilizers, defoamers, chelating agents, pigments and fragrances, and substances such as moisturizers that improve skin tolerance. Other formulation aids include stabilizers, emulsifiers, solvents, and solubilizers.
From tires to toothpaste
Many additives have their own exciting stories to tell as well.
Take fumed silicas: scientists at the former Degussa company in the 1930s searched for a material to replace carbon black, an increasingly scarce resource used as a reinforcing filler in tires, among other applications. Harry Kloepfer, a chemist in the early 1940s, came up with the idea of making a replacement for carbon black from readily available raw materials such as sand and silicates. So instead of oil, he fed silicon tetrachloride into the production furnace, yielding an extremely finely divided silica: AEROSIL®, in other words.
The product has been developed continuously ever since, with the portfolio expanding to encompass a wide range of new variants. In the decades that followed, fumed silicas have been used for polishing microchips, enhancing the pourability of many different powders, making finishes more scratch-resistant, optimizing the flow characteristics of toothpaste, and improving the material properties of engineering rubber products.
And the 2019/2020 coronavirus crisis added one more job to that list: alcohol-based hand sanitizers usually contain carbomers to achieve the proper viscosity. This polyacrylic acid fell into short supply, however, as demand for disinfectants rose steadily. Adding AEROSIL® to disinfectants drastically reduced the amount of carbomer needed.
From fuel to disinfection
Another example is tert-butanol: in Marl, Germany, Evonik’s predecessor Hüls began manufacturing this tertiary alcohol via sulfuric acid extraction back in 1953. The original use for the product was as an antiknock agent or as a fuel additive to prevent carburetor icing. Scientists have since come to use it as a solvent for gas chromatography and, especially, as a precursor in organic peroxides and antioxidants. Initially produced in Marl as a water-alcohol mixture known as an azeotrope, tert-butanol was converted to anhydrous production at the Chemical Park in early 1965. As of 2020, tert-butanol can also be found in alcohol-based hand sanitizers, where it serves as a denaturant, altering the natural smell or taste of the alcohol so that alcohol taxes will not apply.