Metal(iv) phosphates as solid acid catalysts for selective cyclodehydration of 1,n-diols

Abstract

Metal(IV) phosphates of tin, zirconium and titanium are applied, for the first time, as catalysts for selective cyclodehydration of butane-1,4-diol to tetrahydrofuran in high yields. Tin(IV) phosphate showed highest activity among the three, and was used as a catalyst for cyclodehydration of various 1,n-diols. Cyclodehydration of butane-1,4-diol, pentane-1,5-diol, hexane-1,6-diol and diethanolamine gave tetrahydrofuran, tetrahydropyran, oxapane and morpholine, respectively. Cyclodehydration of diethylene glycol, triethylene glycol, diethylene glycol monomethyl ether, polyethylene glycol 200 and polyethylene glycol 300 gave 1,4-dioxane.

Metal (IV) Phosphates as Solid Catalysts for Selective Dehydration of Sorbitol to Isosorbide

“…Every section of acid site of SnPO was higher than that of the other two catalysts. Patel et al [18] have applied amorphous tetravalent metal phosphate-tin phosphate, zirconium phosphate and titanium phosphate as solid acid catalysts for cyclodehydration of 1,n-diols to the corresponding cyclic ethers for the first time. They referred that tin phosphate had the highest activity of the three catalysts.…”

Cyclodehydration of diethylene glycol over Ag-modified Al2O3 catalyst

“…In particular, acidic solids such as TiO 2 -supported silicotungstic acid [2,3], diatomite-supported phosphotungstic acid [4], and ion exchange resin (Indion-130) [5] are efficient for THF formation from BDO in a liquid phase, while 3-buten-1-ol is mainly produced in a vapor phase over base-modified ZrO 2 [6,7], In 2 O 3 [8,9], and rare earth oxides with base property, such as CeO 2 and Er 2 O 3 [10,11]. Such solid catalysts as sulfated zirconia [1], H-ZSM-5 zeolite [12], tin(IV) phosphate [13], and alumina [14] have been reported to be effective for the liquid-phase formation of THP from PDO, while Na-modified monoclinic ZrO 2 [15] and rare earth oxides such as Yb 2 O 3 and Sc 2 O 3 [10,16] prefer the formation of 4-buten-1-ol in a vapor phase.…”

Synthesis of cyclic ethers by cyclodehydration of 1, n -diols using heteropoly acids as catalysts

“…As shown in table 3 , diethylene glycol ( 1e ) gave 1,4-dioxane ( 3e ) in 85% yield, and triethylene glycol ( 1f ) under these conditions gave 1,4-dioxane ( 3e ) in 89% yield. These were significantly higher yields of cyclic ether 3e from diethylene glycol ( 1e ) and triethylene glycol ( 1f ) than previously obtained using other catalyst systems [ 34 – 38 ]. Similarly, polyethylene glycol 200 ( 1g ) gave 1,4-dioxane ( 3e ) in an excellent yield of 86% ( table 3 ).…”

“…Recent advances in the synthesis of substituted THF rings have been achieved using different synthetic methods with novel catalysts and alternative starting materials [ 28 – 33 ]. Additionally, reports of cyclodehydration of 1, n -diols to cyclic ethers have been published; this is essentially a dehydration reaction between two hydroxy groups to yield an ether ( figure 1 ) [ 34 – 38 ]. The present paper reports the application of HPAs as solid acid catalysts for cyclodehydration of 1, n -diols to their corresponding cyclic ethers with high yield and selectivity ( figure 2 ).…”