1‐Butanol is a potential bio‐based fermentation product obtained from cellulosic biomass.As a value‐added chemical,2‐ethyl‐1‐hexanol(2‐EH)can be produced by Guerbet conversion from 1‐butanol.This work reports ...1‐Butanol is a potential bio‐based fermentation product obtained from cellulosic biomass.As a value‐added chemical,2‐ethyl‐1‐hexanol(2‐EH)can be produced by Guerbet conversion from 1‐butanol.This work reports the enhanced catalytic Guerbet reaction of 1‐butanol to 2‐EH by a series of Cp^(*)Ir complexes(Cp^(*):1,2,3,4,5‐pentamethylcyclopenta‐1,3‐diene)coordinated to bipyridine‐type ligands bearing an ortho‐hydroxypyridine group with an electron‐donating group and a Cl−anion.The catalytic activity of the Cp^(*)Ir complex increased by increasing the electron density of the bipyridine ligand when functionalized with the para‐NMe2 and ortho‐hydroxypyridine groups.A record turnover number of 14047 was attained.A mechanistic study indicated that the steric effect of the ethyl group on theα‐C of 2‐ethylhexanal(2‐EHA)and the conjugation effect of C=C–C=O in 2‐ethylhex‐2‐enal(2‐EEA)benefits the high selectivity of 2‐EH from 1‐butanol by inhibiting the cross‐aldol reaction of 2‐EHA and 2‐EEA with butyraldehyde.Nuclear magnetic resonance study revealed the formation of a carbonyl group in the bipyridine‐type ligand via the reaction of the Cp^(*)Ir complex with KOH.展开更多
Dissolution and nucleation are two essential processes for industrial crystallization.This paper in-vestigates the effect of ethylene glycol addition on the crystallization behavior of dimethyl terephthalate(DMT)in so...Dissolution and nucleation are two essential processes for industrial crystallization.This paper in-vestigates the effect of ethylene glycol addition on the crystallization behavior of dimethyl terephthalate(DMT)in solution.The DMT solubility in mixed solvent system(methanol-ethylene glycol)was deter-mined by isothermal satiation approach,and the solubility was associated using seven models.The model fitting results were consistent with the experimental values.Based on the results,the metastable zone width(MSZW)of DMT was detected by the polythermal approach;the modified Sangwal's theory was used to investigate the nucleation behavior,which can provide a new way of thought for better analysis of the crystallization behavior.The results demonstrated that MSZW was associated with various elements,such as cooling rate,saturation temperature and mass fraction of ethylene glycol.The addition of ethylene glycol slowed down the nucleation rate as shown by the broadening of MSZW.We derive the solid-liquid interface energy,the nucleation driving force,the critical nucleation size and the critical Gibbs free energy according to the classical nucleation theory.It is demonstrated that the nucleation driving force and the solid-liquid interface energy are dependent and jointly influence the MSZW.展开更多
文摘1‐Butanol is a potential bio‐based fermentation product obtained from cellulosic biomass.As a value‐added chemical,2‐ethyl‐1‐hexanol(2‐EH)can be produced by Guerbet conversion from 1‐butanol.This work reports the enhanced catalytic Guerbet reaction of 1‐butanol to 2‐EH by a series of Cp^(*)Ir complexes(Cp^(*):1,2,3,4,5‐pentamethylcyclopenta‐1,3‐diene)coordinated to bipyridine‐type ligands bearing an ortho‐hydroxypyridine group with an electron‐donating group and a Cl−anion.The catalytic activity of the Cp^(*)Ir complex increased by increasing the electron density of the bipyridine ligand when functionalized with the para‐NMe2 and ortho‐hydroxypyridine groups.A record turnover number of 14047 was attained.A mechanistic study indicated that the steric effect of the ethyl group on theα‐C of 2‐ethylhexanal(2‐EHA)and the conjugation effect of C=C–C=O in 2‐ethylhex‐2‐enal(2‐EEA)benefits the high selectivity of 2‐EH from 1‐butanol by inhibiting the cross‐aldol reaction of 2‐EHA and 2‐EEA with butyraldehyde.Nuclear magnetic resonance study revealed the formation of a carbonyl group in the bipyridine‐type ligand via the reaction of the Cp^(*)Ir complex with KOH.
基金supported by the National Key Research and Development Program of China(grant No.2019YFC1908201)the Key Program of National Natural Scientific Fund of China(grant No.22238011)+1 种基金the National Natural Science Foundation of China(grant Nos.22178364,21978291)the Natural Science Foundation of Liaoning Province(China)(grant No.2019-ZD-0083).
文摘Dissolution and nucleation are two essential processes for industrial crystallization.This paper in-vestigates the effect of ethylene glycol addition on the crystallization behavior of dimethyl terephthalate(DMT)in solution.The DMT solubility in mixed solvent system(methanol-ethylene glycol)was deter-mined by isothermal satiation approach,and the solubility was associated using seven models.The model fitting results were consistent with the experimental values.Based on the results,the metastable zone width(MSZW)of DMT was detected by the polythermal approach;the modified Sangwal's theory was used to investigate the nucleation behavior,which can provide a new way of thought for better analysis of the crystallization behavior.The results demonstrated that MSZW was associated with various elements,such as cooling rate,saturation temperature and mass fraction of ethylene glycol.The addition of ethylene glycol slowed down the nucleation rate as shown by the broadening of MSZW.We derive the solid-liquid interface energy,the nucleation driving force,the critical nucleation size and the critical Gibbs free energy according to the classical nucleation theory.It is demonstrated that the nucleation driving force and the solid-liquid interface energy are dependent and jointly influence the MSZW.
