The critical signal in maleic acid is that of the vinyl protons, which normally is found in the range5–7 ppm. Maleic acid is compound B.Compound A is malonic acid. Here we have a methylene group bearing two carbonyl substituents.These methylene protons are more shielded than the aldehyde proton of formic acid or the vinyl pro-tons of maleic acid.19.33Compounds A and B both exhibit 1H NMR absorptions in the region 11–12 ppm characteristic ofcarboxylic acids. The formula C4H8O3suggests an index of hydrogen deficiency of 1, accounted forby the carbonyl of the carboxyl group. Compound A has the triplet–quartet splitting indicative of anethyl group, and compound B has two triplets, suggesting —CH2CH2—.19.34(a)The formula of compound A (C3H5ClO2) has an index of hydrogen deficiency of 1—thecarboxyl group. Only two structures are possible:Compound A is determined to be 3-chloropropanoic acid on the basis of its 1H NMR spec-
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