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carbolic acid / phenol

NAME: Carbolic Acid

ALTERATIVE NAME/S: Phenol, or benzenol

DETAILS/DESCRIPTION: Carbolic acid, or phenol, is an acidic hydrocarbon compound, a colourless, low-melting-point, crystalline solid,  first discovered in 1834 by the German pharmacist Runge* when experimenting with coal tar*.

In 1832 Runge had become a research chemist in a chemical factory at Oranienburg (near Berlin) owned by the German Royal Maritime Society, and began by distilling the coal tar that pervaded the works as a waste product of the gas liquor from the Berlin gas works.

Treating the coal tar distillate with hydrochloric acid in order to prepare sal ammoniac, in 1834 Runge produced an acidic substance he called carbolic acid (now named phenol),  was well as aniline (from which he produced two dyes, aniline blue and black), pyrrole, rosolic acid (aurin), and a mixture which later proved to be made up of quinoline, isoquinoline, and quinaldine.  

Five years later, in 1839, pure carbolic acid was first prepared from coal tar by the French chemist August Laurent at Bordeaux, and in 1843 the German chemist von Hoffmann* successfully converted aniline into carbolic acid.

Meanwhile, during the 1830s Runge, like several others, had also discovered that carbolic acid in its crude form - the sticky tar-like substance known as creosote*, also obtained from coal tar - was extremely useful for stopping woodrot in railway sleepers and in ships timbers.

The ability of creosote both to discourage attack by insects and to inhibit decay gradually alerted pharmacists to the possible medical disinfectant/antiseptic qualities of coal tar derivatives (which had been occasionally used in earlier times in the form of pitch), and in 1844 an English physician named Bayard made a disinfecting powder containing coal tar which he used on dressings and applied directly to wounds. A similar preparation was in use by physicians in France in the late 1850s, while around the same time, at the Royal Institution in Manchester, England, an English chemist named Calvert (who had been trained in France) had recognized carbolic acid's disinfectant properties and had begun using it for the preservation of cadavers.

As a result, in 1857 Calvert began manufacturing carbolic acid on a small scale at the Royal Institute, a concern which by 1865 had grown sufficiently to necessitate transfer to a larger works.  The disinfectant properties of carbolic acid became sufficiently known during the mid-19th century that by 1857, it was being used in Carlisle to treat sewage by controlling its decay.

At Glasgow, Scotland, meanwhile, during the same period (unaware of similar work,  by Lemaire,  until 1867), the English surgeon Lister* was also experimenting with carbolic acid as a disinfectant and antiseptic, and within a decade had revolutionized surgical practice by using carbolic acid (phenol) to exclude atmospheric germs and prevent putrefaction in compound fractures of bones. 

In 1861, Lister had been placed in charge of the new surgical block at the Royal Infirmary, Glasgow, a hospital built according to the latest principles of hygienic hospital construction. The mortality rate there proved to be no better than in other hospitals.   Lister had already studied and published on aspects of wound healing and used microscopic analysis in his work, which had led him to reject the generally-held theory connecting infection with bad air, and instead to suggest a kind of infectious agent, like dust or pollen, carried in the air. 

By 1865, Lister had learned both of Pasteur's work on fermentation and putrefaction and of reports that the use of carbolic acid at the Carlisle sewage works had reduced infection among cattle. Now convinced that carbolic acid affected bacteria, Lister  first used carbolic acid to cleanse the wound, but soon became convinced that it was also necessary to create a barrier against further infection, and that the natural scab should become part of that defence.

From his first trial in August 1865, during which he dressed a compound fracture of the tibia with lint soaked in carbolic acid, Lister's technique proved spectacularly successful.  Between 1865 and 1869 surgical mortality in his Male Accident Ward dropped from 45 to 15 percent. In 1866 Lister began to use his method on abcesses, and in 1867 he first used antisepsis during a surgical operation.   Although the reception to Lister's work was mixed,  gradually his fame and techniques spread.  

By the late 1870s, when Lister performed a series of complex operations in London, his antiseptic regime became almost generally accepted in England.  (In the early 1880s, definitive proof of the germ theory was provided by the German microbiologist Robert Koch, who identified the organisms that cause tuberculosis and cholera, and the antiseptic method was at last universally accepted).

ONELINER: Carbolic acid

OTHER CONNECTIONS: None

BIBLIOGRAPHY:

EB

Encyclopedia of the History of Medicine

Short History of Technology

Wikipedia:

Phenol, also known as carbolic acid, is an aromatic organic compound with the molecular formula C6H5OH. It is a white crystalline solid that is volatile. The molecule consists of a phenyl group (-C6H5) bonded to a hydroxyl group (-OH). It is mildly acidic and requires careful handling due to its propensity to cause chemical burns.

@@Phenol was first extracted from coal tar, but today is produced on a large scale (about 7 billion kg/year) from petroleum. It is an important industrial commodity as a precursor to many materials and useful compounds.[5] Its major uses involve its conversion to plastics or related materials. Phenol and its chemical derivatives are key for building polycarbonates, epoxies, Bakelite, nylon, detergents, herbicides such asphenoxy herbicides, and numerous pharmaceutical drugs.

Although similar to alcohols, phenols have unique distinguishing properties. Unlike in alcohols where the hydroxyl group is bound to a saturatedcarbon atom,[6] in phenols the hydroxyl group is attached to an unsaturated aromatic (alternating double and single bond) hydrocarbon ring such as benzene.[7] Consequently, phenols have greater acidity than alcohols due to stabilization of the conjugate base through resonance in the aromatic ring.

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**wikipedia**