4,4′-Dimethylbiphenyl (DMBP)
is a promising platform chemical
for the production of polymer precursors, plasticizers, and metal–organic
frameworks among other materials. We report a two-step process to
produce DMBP from 2-methylfuran (MF) via the formation of the intermediate
5,5′-dimethyl-2,2′-bifuran (DMBF). DMBF is generated
from the Pd-catalyzed oxidative coupling of MF in the presence of
trifluoroacetic acid (TFA) with high selectivity (94%). Optimization
of reaction conditions yields a 20-fold increase in site-time-yield
(STY = 6.99 h–1) compared with a previously reported
protocol. High O2 pressure (7 bar) and a high TFA concentration
(3 M) are critical to improve the DMBF formation rate. For the conversion
of DMBF to DMBP, we show that phosphoric acid supported on silica
(P-SiO2) catalyzes tandem Diels–Alder and dehydration
reactions of DMBF with ethylene to produce DMBP (83% yield). The high
yield and selectivity are a consequence of the weak Brønsted
acid sites in P-SiO2 that dehydrate furan-ethylene cycloadducts
without substantial formation of carbon deposits.
Replacing oil-based toluene with biomass-derived furfural for 4,4′dimethylbiphenyl (DMBP) production can pave the way for sustainable polyester manufacture. This work compared the economic and environmental performances of two conceptual designs of 4,4′-DMBP production. The first toluene-based route consists of toluene alkylation to (methylcyclohexyl)toluene (MCHT), MCHT dehydrogenation to DMBP, and isomerization of lower-valued 3,3′-DMBP. The renewable furfural-based route includes hydrogenation of furfural to 2-methylfuran (MF), oxidative coupling of MF to 5,5′-dimethylfuran (DMBF), and tandem Diels−Alder dehydration of 5,5′-DMBF to 4,4′-DMBP. The reaction conditions are optimized to achieve a more economically feasible process using furfural feedstock. At a scale of 83 kmol/h feedstock, the 4,4′-DMBP minimum selling price of the furfural-based route is $3044/t, while that of the toluene-based route is $2488/t. The feedstock and 3,4′-DMBP isomer prices are identified as critical parameters for the economic evaluation by sensitivity analysis. A "cradle-to-gate" life-cycle assessment confirms that furfural-based DMBP production emits significantly fewer greenhouse gas (5.00 kg CO 2 equiv/kg DMBP) as compared to the toluene-based counterpart (8.28 kg CO 2 equiv/kg DMBP).
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.