Alcohols

Chemical structure
Alcohol consists of linear or branched hydrocarbon chains with one or several OH groups. If there is more than one OH group chemically bonded in one molecule, one speaks of polyhydric alcohol. Ethylene glycol possesses two OH groups in the molecule and is a divalent alcohol, propantriol (glycerin) as trivalent alcohol has three OH groups. The name of the respective alcohol is derived from the molecular structure of the comparable alkanes and gets the ending ‘-ol’.

Chemical structure of ethanol, 1-propanol and 2-propanol:

Ethanol

1-Propanol

2-Propanol

Characteristics
Alcohols possess a broad antimicrobial spectrum of effect, are volatile, have a rapid effect, are only little toxic, only rarely cause allergies and do not produce resistances. Alcohols’ spectrum of effect comprises bacteria, fungi as well as enveloped and non-enveloped virus types – depending on the formulation of the respective alcohol-based use-solution. But bacterial spores remain uninfluenced. The disinfecting effect of alcohols with longer carbon chains is significantly higher and reaches its maximum with six carbon atoms. Due to their water solubility, only ethanol, n-propanol and iso-propanol are used as active ingredients for disinfection today. Use-solutions used for disinfection possess different alcohol concentrations, e.g. ethanol > 70% v/v, n-Propanol > 50 % v/v and iso-propanol > 60 % v/v. Additives can enhance the alcohol’s efficacy and their skin tolerability respectively. Alcohols are volatile and inflammable. Hence, safety rules have to be observed for the storage of alcohol-based disinfectants in order to avoid fire and explosion hazards. In spite of the excellent activity against microorganisms, alcohols are fast and completely biodegradable.

Effect mechanisms
Alcohols possess an unspecific mechanism of effect. The alcohol molecules affect the outer cell membrane, enter the cytoplasm and destroy the inner structure of the cell molecules and of the cytoplasm’s proteins. This process (referred to as denaturation) and the enzymes’ coagulation leads to a loss of cellular activity resulting in the cell’s death.

Fields of application
Today, alcohols play a major role in the industry, e.g. as preserving agent and solvent. As far as disinfection is concerned, alcohols are predominantly used for skin and hand disinfection as well as for the rapid alcohol-based disinfection of smaller surfaces, due to their fast efficacy, skin and material compatibility.