Mindblown: a blog about philosophy.

Naturally occurring carbon is composed almost entirely of the carbon-12 isotope, which has no magnetic moment and thus is not detectable by NMR techniques. However, carbon-13 (13C) atoms, which make up about 1 percent of all carbon atoms, do absorb radio-frequency waves in a manner similar to hydrogen. Thus, 13C NMR is possible, and the technique…

Proton NMR spectra yield a great deal of information about molecular structure because most organic molecules contain many hydrogen atoms, and the hydrogen atoms absorb energy of different wavelengths depending on their bonding environment. NMR absorbances appear in a spectrum as a series of sharp spikes or peaks. Although there is no vertical scale on…

bsorption of long-wavelength (1–5 m) low-energy radiation in the radio-frequency region of the electromagnetic spectrum is due to the atomic nuclei in a molecule. Many (but not all) atomic nuclei have a small magnetic field, which makes them behave somewhat like tiny bar magnets. When placed in a strong external magnetic field, such nuclei can assume…

In organic compounds, atoms are said to be bonded to each other through a σ bond when the two bonded atoms are held together by mutual attraction for the shared electron pair that lies between them. The two atoms do not remain static at a fixed distance from one another, however. They are free to…

Most organic compounds are transparent to the relatively high-energy radiation that constitutes the ultraviolet (200–400 nm) and visible (400–700 nm) portion of the electromagnetic spectrum, and consequently they appear colourless in solution. This is because the electrons in the σ bonds of organic molecules require wavelengths of even higher energy (such as those of X-rays) to excite…

Until the mid-20th century, most organic compounds were distinguished from one another largely on the basis of simple physical and chemical properties. Knowledge of these properties, however, yields only superficial clues about a compound’s molecular structure, and the determination of that structure was a complicated process (for large molecules at least) that involved careful analysis of several…

The product of a synthesis is normally contaminated with reagents used in the synthesis, by-products, and possibly some unchanged starting material; these contaminants must be removed in order for a pure product to be obtained. In a multistep synthesis, it is normally desirable to purify the product from each step before proceeding to the next.

Three factors must be borne in mind when evaluating a particular synthetic plan. The first is cost—of far greater importance in industrial, large-scale synthesis than in laboratory work in which a particular synthesis may be carried out only once, as in the total synthesis of a naturally occurring compound, and which in any case is likely to…

The range of compounds that are capable of being synthesized is essentially limitless. In practice, the synthesis of a preselected compound is made possible by particular functional groups undergoing transformations that, while they are dependent on the conditions applied to the compound, are largely independent of the structure of the remaining part of the molecule. Thus, the combination…

Chemical synthesis is concerned with the construction of complex chemical compounds from simpler ones. A synthesis usually is undertaken for one of three reasons. The first reason is to meet an industrial demand for a product. For example, ammonia is synthesized from nitrogen and hydrogen and is used to make, among other things, ammonium sulfate, employed as a fertilizer; vinyl chloride is made from ethylene and is…