Tuesday, August 02, 2005

UREA WAS NOT THE FIRST EVER ORGANIC COMPOUND SYNTHESIZED IN THE LABORATORY, FROM INORGANIC MATERIALS

Apiece of Research Work in the History of Organic Chemistry
By
Sarabjeet Singh Johar
( President, Chemistry for Humanity & Divinity)

Correction of an historical misrepresentation


The general conception as advanced by our text books of organic chemistry -- Indian or foreign -- that the German chemist FRIEDRICH WOHLER was the pioneer to carry out the first ever synthesis of an organic compound, UREA, by heating ammonium cyanate, must now be discarded. The impression that by synthesizing urea in the laboratory in the year 1828, FREDRICH WOHLER inflicted a death blow to the mysterious “Vital Force Theory” of JONS JAKOB BERZELIUS propounded by him in 1815, is far from truth. It appears that authors of text books as well as historians of chemistry throughout world have overlooked a landmark reaction carried out by a German physicist rather than a German chemist that led to the synthesis of the first ever synthetic organic substance, seven years earlier ( in 1821 ) than the reported work of FRIEDRICH WOHLER ( in 1828 ). Incidentally, the credit of first ever organic synthesis goes to a man namesake of WOHLER ( actually A. WOHLER ). The compound synthesized by A. WOHLER was comparatively complex in structure as compared to simple structural nature of urea prepared, by F. WOHLER. That is why, the problem of resolving the true structure of the “first” organic compound in the history of chemistry continued for 140 years.

When the Vital Force Theory of BERZELIUS was only 6 years old, A. WOHLER had carried out an historical reaction between ammonium thiocyanate and concentrated hydrochloric acid, and isolated a pale yellow crystalline solid, m.p. 200 degree centigrade ( decompn ). It was shown to be a pure organic substance, having the molecular formula H2C2N2S3, and hitherto not isolated from any of the natural sources—plants or animals, was immediately published ( Ann. Physik, 69, 273, 1821 ), but as to the structural formula of the compound, the problem remained unsolved.

NH4CNS + HCl --- H2C2N2S3

This 19th century compound, named isoperthiocyanic acid, remained in total darkness even upto the middle of 20th century. It was only in the year 1961 ( 140 years after its first isolation ) that the structure of isoperthiocyanic acid was resolved by A. HORDVIK ( Acta Chem. Scand., 15, 1186, 1961 ) when he published its electron density maps which showed the presence of two adjacent sulphur atoms in a five-membered ring. The work of A. HORDVIK as well as that of EMELEUS et al. ( H. J. Emeleus, A. Haas, and N. J. Shepperd, J. Org. Chem., 3165, 1963 ) have proved that isoperthiocyanic acid is actually 3-Amino-5-thione-1,2,4-dithiazole.

Laten on, in Germany, United States, and USSR, isoperthiocyanic acid was found useful as a vulcanizing agent for polychloroprene rubber and for chemical colouring of nonferrous metals. It has also found use as an analytical reagent in the laboratory.
Thus, isoperthiocyanic acid has been used for the selective detection of nitrite ion ( G. S. Johar, G. Majumdar, and J. P. Singh, Mikrochim. Acta, 47, 79, 1972 ), determination of cadmium ( M. I. Lebedeva et al., Zh. Anal. Khim., 79, 1440, 1974 ) and determination of niobium ( B. Tamhina and C. Djordjevic, Croat. Chem. Acta, 47, 79, 1975 ). D. A. EDWARDS et al. ( Inorg. Chim. Acta, 23, 215, 1977 ) have worked out the complex formation potential of isoperthiocyanic acid, and have prepared and characterized its palladium( II ), platinum( II ), and copper( I ) complexes.

It should therefore be clear, once and for all, to all the chemistry people -- teachers, researchers, students, etc. -- that it was A. WOHLER who in 1821 had synthesized the first ever organic compound ( isoperthiocyanic acid or 3-Amino-5-thione-1,2,4-dithiazole ) in the laboratory, from inorganic sources. Consequently, the credit of disproving the vital force theory of BERZELIUS goes to A. WOHLER, and not to F. WOHLER.
The sulfocyanic theory on the origin of life

In the early 1930s, Alfonso L. Herrera proposed his so-called sulfocyanic theory on the origin of life, an autotrophic proposal on the first living beings according to which NH4SCN and H2CO ( formaldehyde ) acted as raw materials for the synthesis of bio-organic compounds inside primordial photosynthetic protoplasmic structures. Although the work of Herrera has been frequently cited in historical analysis of the development of the origin of life studies, but confirmatory attention to the chemical significance of the Herrera’s reactions has been given only recently by L. Perezgasga, E. Siilva, A. Lazcano, & A. Negron-Mendoza [ International Journal of Astrobiology (2003), 2:301-306 ]. In their paper the authors have reported the results of their search for amino acids obtained from a reactive mixture used by Herrera from 1933 onwards. Chromatograms using the high-pressure liquid chromatography (HPLC) technique suggest the presence of several amino acids, the total yield being 2% of the initial thiocyanate used. Preliminary identification based on HPLC retention times suggests the presence of glycine, alanine, cysteine and methionine. Alanine was the most abundant amino acid in all samples of fractionated material analysed. Although the starting materials used by Herrera were determined by his autotrophic hypothesis on the origin of cells, but the results obtained by A. Lazcano et al. showed that Herrera’s experiments may provide insights into the abiotic synthesis of sulfur-containing amino acids within the framework of a heterotrophic emergence of life.

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