Chemical Identity Crisis: Glass and Glassblowing in the Identification of Organic Compounds.

This essay explains why and how nineteenth-century chemists sought to stabilize the melting and boiling points of organic substances as reliable characteristics of identity and purity and how, by the end of the century, they established these values as 'Constants of Nature'. Melting and boiling points as characteristic values emerge from this study as products of laboratory standardization, developed by chemists in their struggle to classify, understand and control organic nature. A major argument here concerns the role played by the introduction of organic synthesis in driving these changes. Synthetic organic chemistry vastly increased the number of known organic substances, precipitating the chemical identity crisis of my title. Successful natural product synthesis, moreover, depended on chemists' ability to demonstrate the absolute identity of synthetic product and natural target--something late nineteenth-century chemists eventually achieved by making reliable, replicable melting and boiling point measurements. In the period before the establishment of national standards laboratories, chemists and scientific glassblowers worked together to standardize melting and boiling points as physical constants, such collaborations highlighting the essential importance of chemical glassware and glassblowing skill in the development of nineteenth-century organic chemistry.

[Nepenthe].

Iliad and Odyssey are two major literary sources on various phenomena related to human experience and knowledge. In the Odyssey we find references to the nepenthes, a mythical substance which can change the mood, causing sorrow and anger to be forgotten. We can not identify it with any of the well known substances that have these properties, such as opium from the opium poppy, the Egyptian kyfi or cannabis in the Scythians. Ancient Greeks used various anxiolytic, hypnotic and narcotic substances, but phenomena of addiction or withdrawal are not clearly described, with the exception of wine. Wine was used to lighten peoples minds and hearts, as well as a vehicle for drugs. Many ancient sources describe the negative effects of wine abuse. The study of ancient texts, from Homer's epics to Christian literature, allows a fundamental insight into the influence of psychotropic substances and alcohol on the human psyche.

Overview on the history of organofluorine chemistry from the viewpoint of material industry.

Fluorine (from "le fluor", meaning "to flow") is a second row element of Group 17 in the periodic table. When bound to carbon it forms the strongest bond in organic chemistry to give organofluorine compounds. The scientific field treating them, organofluorine chemistry, started before elemental fluorine itself was isolated. Applying the fruits in academia, industrial organofluorine chemistry has developed over 80 years via dramatic changes during World War II. Nowadays, it provides various materials essential for our society. Recently, it utilizes elemental fluorine itself as a reagent for the introduction of fluorine atoms to organic molecules in leading-edge industries. This paper overviews the historical development of organofluorine chemistry especially from the viewpoint of material industry.

Gas chromatographic and mass spectrometric investigations of organic residues from Roman glass unguentaria.

A combination of gas chromatographic (GC) and mass spectrometric (MS) techniques, including direct exposure-MS (DE-MS), high-temperature GC-MS (HTGC-MS) and GC-MS of neutral and acid fractions, was employed to study the composition and recognise origin of the organic materials used to manufacture balm residues surviving in a series of glass unguentaria recovered from excavations of a Roman villa (Villa B) in the ancient town of Oplontis (Naples, Italy). DE-MS provided comprehensive 'fingerprint' information on the solvent soluble components of the contents of the unguentaria, while GC-MS analyses provided detailed molecular compositions, highlighting the presence of a wide range of compound classes including mid- and long-chain fatty acids, long-chain hydroxy-acids, n-alkanols, alkandiols, n-alkanes, long-chain monoesters, phytosterols and diterpenoid acids. Characteristic biomarkers and their distributions indicate the presence of beeswax, Pinaceae resin and another wax, as the main organic constituents of all of the preparations examined. In particular, the occurrence of phytosterols and long-chain monoesters, in which the acyl moiety was not exclusively palmitic acid, suggested the presence of a second waxy-lipid constituent of plant origin. The results are consistent with beeswax being used in the preparation of the cosmetics preserved in the unguentaria, while the other lipids are most likely the residue of some as yet unidentified plant extract(s), possibly deriving from the cuticular waxes of flowers and/or leaves. The composition of the extracts are consistent with the ancient practices of maceration and/or "enfleurage", in which lipid-based materials, such as beeswax, animal fat or vegetables oils, were used to extract aromatic and fragrant substances from resin, flowers, spices and scented wood, in order to produce unguents and balms.

Combined FT-Raman spectroscopic and mass spectrometric study of ancient Egyptian sarcophagal fragments.

The application of combined Raman spectroscopic and GC-MS analytical techniques for the characterisation of organic varnish residues from Egyptian Dynastic funerary sarcophagal and cartonnage fragments from the Graeco-Roman period, ca. 2200 BP, is described. The nondestructive use of Raman spectroscopy was initially employed to derive information about the specific location of organic material on the specimens, which were then targeted in specific areas using minimal sampling for GC-MS analysis. In the case of the sarcophagal fragment, a degraded yellow-brown surface treatment was identified as a Pistacia spp. resin; this provides additional evidence for the use of this resin, which has previously been identified in Canaanite transport amphorae, varnishes and "incense" bowls in an Egyptian Late Bronze Age archaeological context. The cartonnage fragment also contained an organic coating for which the Raman spectrum indicated a degradation that was too severe to facilitate identification, but the GC-MS data revealed that it was composed of a complex mixture of fatty acid residues. The combined use of GC-MS and Raman spectroscopy for the characterisation of organic materials in an archaeological context is advocated for minimisation of sampling and restriction to specifically identified targets for museum archival specimens.

Perceptions of science. Prebiotic soup--revisiting the Miller experiment.

Also see the archival list of the Essays on Science and Society. PERCEPTIONS IN SCIENCE: Prebiotic Soup--Revisiting the Miller Experiment Jeffrey L. Bada and Antonio Lazcano

Secondary metabolite biosynthesis: the first century.

An account of work on the biosynthesis of secondary metabolites up to 1965 is presented. The earliest suggestions for three of the four major pathways were speculative; for the isoprene rule, hypotheses date to 1877, for the polyketide rule to 1907, and for a role for amino acids in alkaloid biosynthesis to 1910. The fourth major pathway based on intermediates of the shikimic acid pathway has a much shorter history because shikimic acid itself was only identified as a primary metabolite in 1951. In addition to speculation, biomimetic syntheses were carried out in which chemists attempted to duplicate possible biosynthetic pathways in vitro. The classic example was Robinson's synthesis of tropinone in 1917. Direct examination of secondary metabolite biosynthesis was possible with the use of the isotopic tracer technique. This methodology, applied extensively to primary metabolism beginning in 1935 and to secondary metabolism from about 1950, was facilitated by the increasing availability of the 14C isotope. With the use of isotopes as tracers, the broad outlines of secondary metabolite biosynthesis, reviewed here, were established in the period 1950 to 1965.

Materia médica y sustancias psicotropas en el antiguo Perú / Medical material and psychotropas substance in the ancient Perú

Se revisa sucintamente las plantas psicotropas del Perú Precolombino, que forman parte de lo que la medicina occidental llamaba Materia Médica o Farmacéutica, conjunto abigarrado de sustancias orgánicas e inorgánicas suministradas como medicamentos. El conocimiento y el empleo de vegetales de efectos paliativos o curativos era muy importante en las antiguas culturas peruanas, y entre ellas destacaban las alucinógenas. A nivel de conocimiento vegetal, la farmacopea indígena era superior a la que llegaba con los españoles y que reflejaba, en cierta medida, el estado del arte médico en la europa Renacentista. El estudio de las palantas mágicas no puede desligarse del carácter mágico y mítico de la medicina precolombina. Como toda cultura, la defensa instintiva frente al medio agresivo tuvo respuestas místicas e irracionales. Una extensa urdimbre creencial, religiosa, estuvo presente en las diversas etapas de la vida natural del individuo y de la comunidad, por lo que los efectos físicos del uso de los vegetales está enextricablemente unido a las invocaciones y al diagnóstico por adivinación. Los rituales se combinan con los efectos de las plantas en un contexto especial, que aun persiste en la práctica dela medicina tradicional. Finalmente, se examina las áreas de influencia de plantas de efectos psicodislépticos de acuerdo al alcaloide activo: mescalinismo, cocaísmo, harminismo, nicotinismo, daturismo, bufotenismo, entre otros. Se postula una hipótesis sobre el "control social" de esas sustancias en el Perú prehispánico y la presencia vigente de mecanismo similar en nuestros días.