A mass spectrometer produces a spectrum of masses based on the structure of a molecule. It is a spectrum or plot of the distribution of ion masses corresponding to the formula weight of a molecule, fragments derived from the molecule, or both

These spectra are often called carbon magnetic resonance (CMR) spectra or 13C NMR spectra. In some important ways 13C spectra are usually les complex and easier to interpret than proton (1H) NMR spectra

How are molecular structures determined? One way is though the use of spectroscopic methods. Spectroscopy is the study of the interaction of energy with matter. When energy is applied to matter it can be absorbed, emitted, cause a chemical change, or be transmitted

There is a group of compounds in which carbon forms only two bonds. These neutral divalent carbon compounds are called carbenes. Most carbenes are highly unstable compounds that are capable of only fleeting existence. Soon after carbenes are formed they usually react with another molecule

本文参考国内外文献总结了近几年来抗生素去除方法的研究近况。主要包括:(1)抗生素的定义及主要分类;(2)环境中抗生素的来源:(3)抗生素的去除方法(传统处理法、氧化法、吸附法、电化学处理法、薄膜法、超声法、微生物降解法等),详细阐述了每一种处理方法的作用机理及去除效果:(4)对各种抗生素处理方法进行优缺点的总结并对未来应用做了展望

In the addition of HX to an unsymmetrically substituted alkene, the hydrogen atom adds to the carbon atom of the double bond that already has the greater number of hydrogen atoms and that the X group adds to the carbon having more alkyl substituents. Markovnikov’s rule can be restated by saying that, in the addition of HX to an alkene, the more stable carbocation intermediate is formed

Compounds were classified as being either aliphatic or aromatic in the latter part of the nineteenth century. To be classified as aliphatic meant then that the chemical behavior of a compound was “fatlike”. To be classified as aromatic meant then that the compound had a low hydrogen/carbon ratio and that it was “fragrant

1. The experimental conditions — temperature and acid concentration — that are required to being about dehydration are closely related to the structure of the individual alcohol. The relative ease with which alcohols undergo dehydration is in the following order:

A UV-Vis spectrophotometer measures the amount of light absorbed at each wavelength of the UV and visible regions of the electromagnetic spectrum. λmax— the wavelength of maximum absorption

SN2 reactions are highly useful in organic synthesis because they enable use to convert one functional group into another —— functional group transformation (functional group interconversion)