Question

a) Grignard reagents react with oxirane (ethylene oxide) to form 1° alcohols but can be prepared in tetrahydrofuran (THF) solvent. Why is this difference in behavior observed? Explain clearly b) A compound has the formula CsHio, with the 13C and IH NMR spectral data shown. Propose a structure that fits this data. BC NMR Broadband decoupled 13C NMR: 23.5, 26.7, 68.9 δ DEPT-90: no peaks DEPT-135: no positive peaks negative peaks at 23.5, 267, 689 δ HNMR 1.7 δ, multiplet (6H) 3.72 δ, triplet (4H)J-7 ㎐

Answer 1

Grignard reagent (R-Mgx) reacts with oxidase as follows The reaction is feasible because oxidase is 3-membered highly strained molecule. To release the strain oxidase is very reactive towards Grignard reagent. On the other hand tetrahydrofuran is a five-membered highly stable molecule. There is no strain in the ring. Hence it does not react with Grignard reagent. Molecular formula = C_5H_10 O Double bond equivalent = 2 times 5 - 10 + 2/2 = 1 Proton NMR indicates the presence of only two type protons. The structure of the compound N.B: The given molecular formula is wrong. It should be C_5H_10O