Saturday 26 December 2009

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At the beginning of the nineteenth century, chemists generally thought that compounds obtained from living organisms were too complex to be obtained synthetically. According to the concept of vitalism, organic matter was endowed with a 'vital force'. They named these compounds 'organic' and directed their investigations toward inorganic materials that seemed more easily studied

Over the course of the first half of the nineteenth century, it was realized that organic compounds could in fact be synthesized in the laboratory. Around 1816 Michel Chevreul started a study of soaps made from various fats and alkali. He separated the different acids that, in combination with the alkali, produced the soap. Since these were all individual compounds, he demonstrated that it was possible to make a chemical change in various fats (which traditionally come from organic sources), producing new compounds, without 'vital force'. In 1828 Friedrich Wöhler produced the organic chemical urea (carbamide), a constituent of urine, from the inorganic ammonium cyanate NH4OCN, in what is now called the Wöhler synthesis. Although Wöhler was, at this time as well as afterwards, cautious about claiming that he had thereby destroyed the theory of vital force, historians have looked to this event as the turning point.

A great next step was when in 1856 William Henry Perkin, while trying to manufacture quinine, again accidentally came to manufacture the organic dye now called Perkin's mauve, which by generating a huge amount of money greatly increased interest in organic chemistry.

The crucial breakthrough for the organic chemistry was the concept of chemical structure, developed independently and simultaneously by Friedrich August Kekule and Archibald Scott Couper in 1858. Both men suggested that tetravalent carbon atoms could link to each other to form a carbon lattice, and that the detailed patterns of atomic bonding could be discerned by skillful interpretations of appropriate chemical reactions.

The history of organic chemistry continued with the discovery of petroleum and its separation into fractions according to boiling ranges. The conversion of different compound types or individual compounds by various chemical processes created the petroleum chemistry leading to the birth of the petrochemical industry, which successfully manufactured artificial rubbers, the various organic adhesives, the property-modifying petroleum additives, and plastics.

The pharmaceutical industry began in the last decade of the 19th century when acetylsalicylic acid (more commonly referred to as aspirin) manufacture was started in Germany by Bayer. The first time a drug was systematically improved was with arsphenamine (Salvarsan). Numerous derivatives of the dangerously toxic atoxyl were examined by Paul Ehrlich and his group, and the compound with best effectiveness and toxicity characteristics was selected for production.

Although early examples of organic reactions and applications were often serendipitous, the latter half of the 19th century witnessed highly systematic studies of organic compounds. Beginning in the 20th century, progress of organic chemistry allowed the synthesis of highly complex molecules via multistep procedures. Concurrently, polymers and enzymes were understood to be large organic molecules, and petroleum was shown to be of biological origin. The process of finding new synthesis routes for a given compound is called total synthesis. Total synthesis of complex natural compounds started with urea, increased in complexity to glucose and terpineol, and in 1907, total synthesis was commercialized the first time by Gustaf Komppa with camphor. Pharmaceutical benefits have been substantial, for example cholesterol-related compounds have opened ways to synthesis of complex human hormones and their modified derivatives. Since the start of the 20th century, complexity of total syntheses has been increasing, with examples such as lysergic acid and vitamin B12. Today's targets feature tens of stereogenic centers that must be synthesized correctly with asymmetric synthesis.

Biochemistry, the chemistry of living organisms, their structure and interactions in vitro and inside living systems, has only started in the 20th century, opening up a new chapter of organic chemistry with enormous scope. Biochemistry, like organic chemistry, primarily focuses on compounds containing carbon as well.

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