Phenolic active ingredients in modern disinfectant formulations
Dr Kelly Board , head of R & D – actives at Lanxess ’ s Material Protection Products business unit , reviews the current and potential applications of phenolics
Phenolic compounds have a long and established history as antimicrobial agents that can be traced back over 200 years . 1 Joseph Lister ’ s pioneering work in the 1860s used phenol ( carbolic acid , as it was known then ) to clean wounds and sterilise instruments . At around the same time , the coal industry discovered the disinfectant properties of coal tar acids obtained from the fractional distillation of coal . These complex mixtures were comprised primarily of phenols , cresols and xylenols . Fast-forward to today and the highly regulated world of the disinfectant industry - synthetic phenolic compounds have superseded toxic phenol and coal tar acids . But what are these compounds and what makes them a viable choice for today ’ s disinfectant formulators ? Synthetic phenolic compounds are substituted phenol moieties that are produced efficiently and at scale . The substituents on the phenyl ring can be aryl , alkyl and / or halo groups , amongst others , and the type and position of the substituents influence the biocidal properties .
Impact of regulations
When it comes to selecting a phenolic active ingredient for a disinfectant formulation , the first step in the process is not necessarily ‘ What can the active do ?’ but rather ‘ Which active am I allowed to use ?’ In Europe , active substances must be approved according to the Biocidal Products Regulation ( EU ) 528 / 2012
( BPR ) in the appropriate Product Type ( PT ) for the end use application . Table 1 shows examples of commercially available synthetic phenolic compounds and their BPR status . One consequence of this legislation is the reduced number of supported and approved active substances and products available on the market . Formulators are constantly challenged with making new products with fewer active ingredients . Compounding this challenge are the financial and regulatory commitments required to bring an authorised disinfectant product to market . The formulator must have confidence that
Table 1 – Common commercially available synthetic phenolic compounds & their BPR status
Chemical name Alternative name
BPR biocidal active substance status 2 *
Biphenyl-2-ol o-phenylphenol ( OPP ) Approved : PT 1 , 2 , 3 , 4 Chlorocresol p-chloro-m-cresol ( PCMC ) Approved : PT 1 , 2 , 3 5-chloro-2- ( 4-chlorophenoxy ) phenol DCPP Approved : PT 1 , 2 , 4 Chloroxylenol p-chloro-m-xylenol ( PCMX ) Not supported 2-phenoxyethanol Ethylene glycol monophenyl ether Approval in progress : PT 1 , 2 , 4 . Not approved : PT 3 Salicylic acid 2-Hydroxybenzoic acid Approval in progress : PT 2 , 3 , 4 Triclosan TCS Not approved : PT 1 , 2
* Considering PTs under Main Group 1 – disinfectants only . PT 1 - Human hygiene , PT 2 - Disinfectants & algaecides not intended for direct application to humans or animals , PT 3 - Veterinary hygiene , PT 4 - Food & feed area
54 SPECIALITY CHEMICALS MAGAZINE ESTABLISHED 1981