Butanols derivative spectra

The one-dimensional variations of the INADEQUATE experiment suppress the intense C- C main signal, so that both AX and AB systems appear for all C— C bonds in one spectrum. The two-dimensional variations segregate these AB systems on the basis of their individual double quantum frequencies (the sum of the C shifts of A and B) as a second dimension. Using the simple example of 1-butanol (12), Fig. 2.12a demonstrates the use of the two-dimensional INADEQUATE technique for the purpose of structure elucidation. For every C—C bond the contour diagram gives an AB system parallel to the abscissa with double quantum frequency as ordinate. By following the arrows in Fig. 2.12a, the carbon connectivities of butanol can be derived immediately. The individual AB systems may also be shown one-dimension-ally (Fig. 2.12b) the C- C coupling constants often provide useful additional information. 

In the deprotection of peracetylated polyphenolic compounds a somewhat different scheme has emerged. In this area, a broader spectrum of lipases has been used successfully. For example, the pentaacetyl derivative of catechine 179 was treated with PSL under alcoholysis conditions (THF, n-butanol) to give the 3,3, 4 -trisacetate in 50% yield after 12 hours12781. On longer exposure to the biocatalyst, the 3-monoacetyl derivative was isolated in 95 % yield. 

Sanchez and Brown have obtained a new harman derivative from Aspi-dosperma exalatum Monachino (121). The alkaloid was obtained from a butanol extract, and in the IR spectrum it showed principal absorptions at 1925 cm-1 for an immonium ion, at 1610 cm-1 for a carboxylate anion, and at 748 cm-1 for a disubstituted benzene. In the mass spectrum a molecular ion was observed at m/e 226 and a base peak at m/e 182 (M+ —44). An aromatic methyl group and five aromatic protons were observed in the PMR spectrum. Consideration of this data together with the UV spectrum led to deduction of the structure of the alkaloid as 268, harman carboxylic acid. The ethyl ester (269) was also isolated but it was probably an artifact. 

In some cases, components in a mixture can be determined quantitatively without prior separation if the mass spectrum of each component is sufficiently different from the others. Suppose that a sample is known to contain only the butanol isomers listed in Table 10.17. It can be seen from Table 10.17 that the peak at miz = 33 is derived from butanol, but not from the other two isomers. A measurement of the miz = 33 peak intensity compared to butanol standards of known concentration would therefore provide a basis for measuring the butanol content of the mixture. Also, we can see that the abundances of the peaks at m z = 45, 56, and 59 vary greatly among the isomers. Three simultaneous equations with three unknowns can be obtained by measuring the actual abundances of these three peaks in the sample and applying the ratio of the abundances from pure compounds. The three unknown values are the percentages of butanol, 2-butanol, and 2-methyl-2-propanol in the mixture. The three equations can be solved and the composition of the sample determined. Computer programs can be written to process the data from multicomponent systems, make all necessary corrections, and calculate the results. 

The first overtone of a free hydroxyl group in dilute CCI4 solution or a low-density gas is at about 7090 cm (1410 nm). This peak is at different positions for primary, secondary, and tertiary alcohols, as seen in Figure 5.1. Primary and secondary butanols can be split into doublets by rotational isomerization. The splits are better seen in Figure 5.2, in the second derivation spectra of the same spectral region. Maeda et al. observed an additional peak in the first overtone region when they subtracted the spectrum at a lower temperature from that at a higher one. They felt that temperature effects further separated species that were weakly bonded to the carbon tetrachloride solvent and a terminal free OH of a self-associated species. 

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