Selective　valorization　of　lignin　to　achieve　high　value　and　commodity　chemicals　is　attracting　increasing　attention.　In　this　work,　an　efficient　and　reusable　metal-based　ionic　liquid　(MBIL)　was　developed　for　the　selective　tailoring　of　p-coumaric　acid　ester　(pCA),　a　typical　p-hydroxyphenyl　(H)　unit,　into　methyl　p-hydroxycinnamate　(MPC).　Under　optimized　conditions　and　in　the　presence　of　catalyst　[Bmim][FeCl4],　a　volatile　aromatic　product　of　10.5　wt%　was　obtained,　of　which,　70.5%　separated　as　pure　MPC　with　an　isolated　yield　of　71.1　mg　g-1.　FT-IR,　13C　NMR,　ANO　and　2D　HSQC　demonstrated　that　the　H　unit　was　preferentially　tailored　from　lignin,　of　which,　86.0　wt%　of　the　H　structure　unit　is　cut　off　from　lignin,　with　70.6%　being　selectively　converted　to　MPC.　Further　investigation　demonstrated　that　MBIL　prefers　to　tailor　ester　bonds　compared　to　ether　bonds　using　model　compounds,　and　the　superior　catalytic　ester　bond　cleavage　performance　exhibited　by　[Bmim][FeCl4]　can　be　ascribed　to　the　relatively　narrow　energy　gap　between　the　lignin　ester　bond　and　[FeCl4]-　anion　and　to　the　comparatively　low　absolute　binding　energy　between　the　cation　and　anion　through　DFT　calculations.　©　The　Royal　Society　of　Chemistry　2018.