Mindblown: a blog about philosophy.

The formation of new bonds in a molecule by the removal of atoms takes place in an elimination reaction. These reactions are often responsible for the formation of double bonds, as in the formation of an alkene from an alcohol by the action of concentrated sulfuric acid, and for the thermal elimination of hydrogen chloride to make chloroethene.

The simple replacement of one atom or group of atoms in a molecule by a second atom or group of atoms is called a substitution reaction. An illustrative example is the conversion of benzyl bromide to benzyl alcohol, using a solution of sodium hydroxide in water. In this reaction the bromine atom of the benzyl bromide has been replaced by the hydroxyl group of…

The electronic features of functional groups are responsible for the types of reactions that are characteristic of each group. Because there is a great deal of similarity in the electronic characteristics of the different functional groups, there is a corresponding similarity in the types of reaction that different groups undergo. Just as the properties of…

Mass spectrometry differs from the types of spectroscopy previously discussed because the molecular information that the technique provides does not depend on absorption of electromagnetic radiation. In a mass spectrometer, molecules are converted to charged fragments called ions, which are then separated according to their masses. The chart that records the masses of the fragments…

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…