Molecular formulas, using mass spectroscopy determine

Nuclear Magnetic Resonance spectrometry is used for many types of analytical work but is key in the elucidation of structures of chemical compounds. When used in conjunction with mass spectrometry and infrared spectroscopy, the three techniques make it possible to determine the complete structures of novel compounds. Mass spectrometry is used to determine the size of a molecule and its molecular formula and infrared spectroscopy help identify the functional groups present in a molecule. NMR spectroscopy is used to determine the carbon-hydrogen framework of a molecule and works with even the most complex molecules. NMR is now being used to elucidate complicated protein structures ... 

Mass spectrometry and IR spectroscopy give valuable but limited information on the identity of an unknown. Although the mass spectral and IR data reveal that X has a molecular formula of C4Hg02 and contains a carbonyl group, more data are needed to determine its complete structure. In Chapter 14, we will learn how other spectroscopic data can be used for that purpose. 

In this scheme, the most computationally time-consuming procedure is the connection of the atoms or substructures to generate structure candidates. We illustrate this scheme via elucidation of the structure of gib-berellic acid (GBA). The molecular formula of gibberellic acid was determined as C19H22O5 from mass spectroscopy. By using a C distortionless... 

Today, a number of different instrumental techniques are used to identify organic compounds. These techniques can be performed quickly on small amounts of a compound and can provide much more information about the compound s structure than simple chemical tests can provide. We have already discussed one such technique ultraviolet/visible (UVA/is) spectroscopy, which provides information about organic compounds with conjugated double bonds. In this chapter, we will look at two more instrumental techniques mass spectrometry and infrared (IR) spectroscopy. Mass spectrometry allows us to determine the molecular mass and the molecular formula of a compound, as well as certain structural features of the compound. Infrared spectroscopy allows us to determine the kinds of functional groups a compound has. In the next chapter, we will look at nuclear magnetic resonance (NMR) spectroscopy, which provides information about the carbon-hydrogen framework of a compound. Of these instrumental techniques, mass spectrometry is the only one that does not involve electromagnetic radiation. Thus, it is called spectrometry, whereas the others are called spectroscopy. 

In the beginning of this chapter, we defined spectroscopy as the study of the interaction between matter and electromagnetic radiation. In contrast, mass spectrometry is the study of the interaction between matter and an energy source other than electromagnetic radiation. Mass spectrometry is used primarily to determine the molecular weight and molecular formula of a compound. 

The structure of an organic molecule is usually determined using spectroscopic methods such as mass spectrometry and infrared spectroscopy. Mass spectrometry (MS) tells the molecular weight and formula of a molecule infrared (IR) spectroscopy identifies the functional grou[is present in the molecule. 

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