Tetrazole ethers from lignin model phenols: synthesis, crystal structures, and photostability

{The phenolic OH moiety in lignin is one of the key functional groups responsible for the photo-induced yellowing of mechanical wood pulps and papers. To evaluate new protective groups for the stabilization of lignin phenols, the model compounds, 2-methoxy-4-propylphenol (1) and 4-hydroxy-3-methoxyacetophenone (2) were reacted with 5-chloro-1-phenyl-1H-tetrazole to give the corresponding tetrazole ethers 1’ and 2’, respectively, that were then studied for their photostability. The synthesis of these ethers was more efficient than that of alkyl ethers because of less hydrolysis of the alkylating agent under the reaction conditions. Compounds 1’ and 2’ were fully characterized, including X-ray crystal structure analyses. Crystals of 1’ and 2’ were monoclinic of space groups P2(1)/c and P2(1)/a, respectively. For 1’: a = 9.8679(6)