儀器分析補(bǔ)充2

1、ExerciseFormula of compound A is C5H8O2, its UV maximum absorption wavelength is 208nm, chemical analysis has proved that it is not ester. Figure 10.4 is IR spectra of the compound, Please give its possible structure.1Degree of unsaturation:=1+n4+(n3-n1)/2=1+5+(0-8)/2=2 According UV spectral charact

2、eristic(lmax =208nm), the compound might be a a,b-single-substituted alkenyl ester (or anhydride or ketone, a,b-單取代烯酯, 烯醛或烯酮) Above result suggests that there are two unsaturated bonds in the molecule, excluding saturated compounds, aromatics以上結(jié)果表明, 該化合物不可能為飽和化合物及芳香族化合物, 可能為雙鍵單取代a,b-不飽和羰基化合物.2In the

3、 IR spectra, there is a strong absorption peak at 1730cm-1, it indicates existence of carboxyl(C=O). A weak peak in the 1600-1680cm-1 means existence of C=C-(stretching vibration)(可能為稀烴)以上特征表明,該化合物不可能為醇, 酚和炔類化合物, 可能含有烯鍵, 和羰基.No absorption bands in the higher frequency region than 3200cm-1, excluding

4、 existence of OH, for example, alcohols, phenols, and acids.No absorption band at 2200cm-1, excluding alkynes(炔).3以上特征表明, 該化合物中含有-CH3, -C=O, 和端基雙鍵An absorption band at 1450cm-1 means existence of CH3(symmetrical bend). Strong peaks in the region of 1150-1200cm-1 suggest C-O .Two peaks at 920cm-1 and

5、 1020cm-1 are respectively out-of- plane bending vibrations of C-H bond of C=CH2 group(端基稀烴) There are some middle strong sharp peaks in the region of 2850-3050cm-1, which indicates existence of unsaturated C=C-H and saturated C-H.-CH2-H-C-O-C=CH-HSaturated & unsaturated C-H3000200010006004根據(jù)題意,該化合物不含醚氧原子, 因此, 分子中的兩個(gè)氧原子只可能以酯基的形式存在。除去兩個(gè)雙鍵碳原子和一個(gè)羰基碳原子, 剩余兩個(gè)碳原子中只