Caro, H
ACHIEVEMENTS:
Created methylene blue.
DATE AND PLACE OF BIRTH:
?13 February 1834, Poznan, Poland
DATE AND PLACE OF DEATH AND AGE AT DEATH:
11 October 1910, Dresden, Germany. Aged 76
DISCIPLINE:Chemist
FIELD:Dye chemistry
EDUCATION:
High School, Berlin
Technical School, Berlin
MAJOR WORK:None
LIFE AND TIMES:
While training as a dyer at technical school, Caro attended chemistry lectures at Berlin University. In 1855 he began work in a calico printing firm. Caro used his training to demonstrate scientific methods in solving production problems and in 1857 he was sent to England to study the latest dyeing methods.In 1859 he resigned from the calico factory and returned to England where Perkin’s* success in obtaining amauve dye from aniline had triggered a burst of research in synthetic dyes. Caro took a job as analytical chemist for the chemical firm of Roberts, Dale & Co., in Manchester, the centre of the textile industry in the north of England. He discovered a more efficient way of making Perkin mauve and became a partner in the firm.
Over the following five years he kept up with new developments (in particular those of von Hoffman*) on the new aniline dyes, and also pursued his own research. He discovered an aniline dye called induline and in 1864-5, in collaboration with C A Martius, discovered and developed a commercially applicable synthesis for the colours Bismarck brown and Martius yellow. He also began working on the structure of rosaniline dyes.
Like most of his contemporaries, Caro saw that there were more opportunities in the new German synthetic dye industry than in England. In 1866 Caro returned to Germany with his English wife and settled in Heidelberg where he worked as a research chemist in Bunsen's* laboratory. In 1868 he became the director of the Ludwigshafen Badische Anilin- & Soda-Fabrik (BASF), probably the first modern industrial research organisation.
Caro always kept up with current research at all levels and maintained contact with researchers in universities and other laboratories. He was now at the forefront of the rapidly expanding German dye industry. In 1869 laboratory contacts demonstrated their new synthesis of alizarin which was commercially impracticable owing to the high cost of the bromine used in the process to act on anthraquinone. By experiment and good luck, Caro solved the problem (BASF had a large quantity of anthraquinone for which they had not discovered a use. Caro had the idea of making a dye by heating the anthraquinone with oxalic acid and sulphuric acid. He did so and had just noticed that the oxalic acid decomposed and vanished, when he was called away. He came back to find a pink crust on the charred residue. It was alizarin.)
In 1874 he adapted the fluorescein discovered by von Baeyer* to produce eosin, a fluorescent red dye. He worked with Baeyer to make methylene blue (later used by Ehrlich* to stain bacteria) and related dyes. When azo reactions were developed in the mid-1870's, Caro co-discovered and commercially produced chrysoidine, orange and fast red.
In 1879 he discovered naphthol yellow and a year later he again collaborated with Baeyer in an attempt to obtain a commercial synthesis of indigo from cinnamic acid (which was derived from benzal chloride).By now Golgi's* discovery and use of dye in medical science had expanded the application of dyes and German medical scientists were quick to follow suit.
In 1889 Caro resigned as director of research but continued to work, and in 1898 discovered persulphuric acid, which is now known as ‘Caro's acid.’ In addition to his laboratory work Caro contributed to the establishment of efficient patent laws and recorded in articles and speeches the development of the dye industry during his lifetime.
ASSESSMENT: Caro was an outstanding research chemist who was one of the most notable contributors to the successful commercialization of the German syntheticdye industry during the nineteenth century.
EXTRA CONNECTIONS: His work related to that of Fischer*, Kirchhoff*, and Koch*.
ONELINER: Heinrich Caro, outstanding German dye chemist
BIBLIOGRAPHY:
DSB
Singer, C., History of Technology
LANGUAGE:
German
PARENTS:
Unknown
SIBLINGS:
Unknown
SPOUSE:
Edith Eaton
CHILDREN:
Unknown