Figure 1.

GC‐MS chromatograms of (a) 4‐MeTHP, (b) THP and (c) 2‐MeTHF after two recycles. Peak assignments were made by comparison with the reference data (NIST 14 mass spectral library) or the retention time of authentic samples. A=isobutyronitrile; B=H₂O; C=isopentyl formate; D=1‐butanol; E=isopentanol; F=2‐methyltetrahydropyran; G=3‐methyltetrahydropyran; H=n‐butyl formate; I=2,4‐dimethylpentanenitrile; J=sec‐butyl formate; K=n‐propyl acetate; L=unidentifiable; M=2‐butanol; N=5‐methyltetrahydrofuran‐2‐ol (This peak may contain 5‐methyl‐2,3‐dihydrofuran derived from degradation of 5‐hydroxypentan‐2‐one); O=γ‐valerolactone; P=5‐hydroxypentan‐2‐one.