Functional group, carbon determination

The thermal decomposition model was developed by using parameters derived from the decomposition experiments (1, 2, 3). The observed relationship between the products and the functional group compositions determined from IR measurements indicates that several of these model parameters may be obtained directly from the IR spectra. A comparison of parameters determined from the thermal decomposition experiments with those determined from the IR measurements is made in Figure 14. Figure 14(a) shows the results for aliphatic CH. For the IR determination it has been assumed that the aliphatics have the stoichiometry CHj g (18). Figure 14(b) shows the results for aromatic carbon. 

The functional group that determines an alcohol is —OH. The carbon atom having the —OH group is attached to another carbon atom by a single bond and is sp3 hybridised. The carbon chain of the rest of the alcohol can be saturated or unsaturated. 

Key point. Organic compounds are classified by functional groups which determine their chemistry. The names of organic compounds are derived from the functional group (or groups) and the main carbon chain. From the name, the structure of organic compounds can be drawn using KekuU, condensed or skeletal structures. 

Compound (30) showed a ketone, a carboxylic carbon, one double bond and one oxygenated methine in its 13C NMR spectrum. Its spectroscopic l3C NMR data were very similar of that of ursolic acid [51]. The position of the functional groups were determined by means of a HMBC experiment and the stereochemistry of H-22 was determined based on its coupling constant, indicating an equatorial configuration. Therefore, (30) was elucidated to be 22p-hydroxy-3-oxo-12-ursen-30-oic acid, Fig. (21). 

Compare the number of carbons and functional groups to determine if each compound is soluble in... 

We will examine the products that would result from cleaving of all the possible combinations of bonds in a monosaccharide. We will do so by considering various subunits of the structme. However, all the subunits react, so we must analyze all carbon-carbon bonds and the attached functional groups to determine the products that can form. First, consider the subunit that contains a primary hydroxyl group. This structural feature exists at the highest numbered carbon atom of an aldose. The unit also occurs at C-1 and the highest numbered carbon atom of a ketose. 

Substitutive Nomenclature. The first step is to determine the kind of characteristic (functional) group for use as the principal group of the parent compound. A characteristic group is a recognized combination of atoms that confers characteristic chemical properties on the molecule in which it occurs. Carbon-to-carbon unsaturation and heteroatoms in rings are considered nonfunctional for nomenclature purposes. 

We saw in Chapter 12 that mass spectrometry gives a molecule s formula and infrared spectroscopy identifies a molecule s functional groups. Nuclear magnetic resonance spectroscopy does not replace either of these techniques rather, it complements them by "mapping" a molecule s carbon-hydrogen framework. Taken together, mass spectrometry, JR, and NMR make it possible to determine the structures of even very complex molecules. 

We re almost ready to start naming molecules. We finished learning about the individual parts of a name, and now we need to know how to identify how the pieces are connected. For example, let s say you determine that the functional group is OH (therefore, the suffix is -ol), there is one double bond (-en-), the parent chain is six carbon atoms long (hex), there are four methyl groups attached to the parent chain (tetramethyl), and the double bond is cis. Now you know all of the pieces, but we must find a way to identify where all of the pieces are on the parent chain. Where are all of those methyl groups (and so on). This is where the numbering system comes in. First we will learn how to number the parent chain, and then we will learn the rules of how to apply those numbers in each part of the name. 

The potentiometric titration was carried out in order to determine the functional groups present in the biomass surface. During the titration experiments, the C02-free condition was always maintained to avoid the influence of inorganic carbon on the solution pH. Detailed potentiometric titration procedure and estimation method of functional groups are available in the previous reports [4,6]. 

Previous authors have taught the principles of solving organic structures from spectra by using a combination of methods NMR, infrared spectroscopy (IR), ultraviolet spectroscopy (UV) and mass spectrometry (MS). However, the information available from UV and MS is limited in its predictive capability, and IR is useful mainly for determining the presence of functional groups, many of which are also visible in carbon-13 NMR spectra. Additional information such as elemental analysis values or molecular weights is also often presented. 

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