Continuous process for the manufacture of 2,5-dihydrofurans from .gamma., .delta.-epoxybutenes

Continuous process for the manufacture of a 2,5-dihydrofuran containing 4 to 8 carbon atoms and the formula ##STR8## by the steps comprising:

• (1) continuously feeding a .gamma.,.delta.-epoxyalkene having the formula ##STR9## to a reaction zone containing a solution of:
• (A) a catalytic amount of a catalyst system comprising (i) an onium iodide and (ii) an organotin (IV) compound;
• and
• (B) a mixture of the 2,5-dihydrofuran product and an oligomer of the .gamma.,.delta.-epoxyalkene reactant;
• and
• (2) continuously removing a vapor comprising the 2,5-dihydrofuran from the reaction zone solution;
• wherein the liquid phase of the reaction zone is maintained at a temperature of about 65.degree. to 160.degree. C., the concentration of the catalyst system in the reaction zone liquid is maintained at about 50 to 90 weight percent, based on the total weight of the reaction zone liquid, and each R.sup.1 substituent is independently selected from hydrogen and methyl.

Continuous process for the manufacture of 2,5-dihydrofuran by the steps comprising:

• (1) continuously feeding 3,4-epoxy-1-butene to a reaction zone containing a solution of:
• (A) a catalytic amount of a catalyst system comprising (i) a quaternary phosphonium iodide having a total of about 16 to 60 carbon atoms and the formula:
• ##STR13## and (ii) an organotin (IV) compound having the formula:
• (R.sup.7).sub.3 --Sn--I
• wherein each R.sup.6 substituent is independently selected from alkyl of up to about 20 carbon atoms, benzyl, phenyl or phenyl substituted with up to 3 substituents selected from lower alkyl, lower alkoxy or halogen;
• each R.sup.7 substituent is independently selected from alkyl of up to about 12 carbon atoms, benzyl, 2-methyl-2-phenylpropyl, phenyl or phenyl substituted with up to 3 substituents selected from lower alkyl, lower alkoxy or halogen;
• and the mole ratio of (i):(ii) is about 10:1 to 0.1:1;
• and
• (B) a mixture of 2,5-dihydrofuran and an oligomer of 3,4-epoxy-1-butene;
• and
• (2) continuously removing a vapor comprising 2,5-dihydrofuran from the reaction zone;
• wherein the liquid phase of the reaction zone is maintained at a temperature of about 80.degree. to 120.degree. C. and the concentration of the catalyst system in the reaction zone liquid is maintained at about 50 to 90 weight percent, based on the total weight of the reaction zone liquid.

Continuous process for the manufacture of a 2,5-dihydrofuran containing 4 to 8 carbon atoms and the formula ##STR15## by the steps comprising:

• (1) continuously feeding a homogeneous mixture comprising a .gamma.,.delta.-epoxyalkene having the formula ##STR16## and the liquid phase of step (3)(b) to a reaction zone:
• (2) continuously removing from the reaction zone a homogeneous liquid comprising a 2,5-dihydrofuran product having the formula ##STR17## an oligomer of the .gamma.,.delta.-epoxyalkene reactant and the catalyst components, and
• (3) continuously feeding the homogeneous liquid of step (2) to a distillation zone to obtain:
• (a) a vapor phase rich in the 2,5-dihydrofuran product;
• and
• (b) a liquid phase comprising the 2,5-dihydrofuran product, an oligomer of the .gamma.,.delta.-epoxyalkene reactant and the catalyst components;
• wherein the catalyst components comprise (i) an onium iodide and (ii) a Lewis acid selected from inorganic Lewis acids, an organotin (IV) compound, an organostibonium compound or a mixture thereof;
• the concentration of the catalyst system in the reaction zone liquid is maintained at about 10 to 95 weight percent, based on the total weight of the reaction zone liquid;
• and the liquid phase of the reaction zone is maintained at a temperature of about 65.degree. to 160.degree. C.

Process for the manufacture of 2,5-dihydrofuran by the steps comprising:

• (1) continuously feeding a homogeneous mixture comprising 3,4-epoxy-1-butene and the liquid phase of step (3)(b) to a reaction zone;
• (2) continuously removing from the reaction zone a homogeneous liquid comprising 2,5-dihydrofuran product, an oligomer of 3,4-epoxy-1-butene and catalyst components;
• and
• (3) continuously feeding the homogeneous liquid of step (2) to a distillation zone to obtain:
• (a) a vapor phase rich in 2,5-dihydrofuran;
• and
• (b) a liquid phase comprising 2,5-dihydrofuran product, an oligomer of 3,4-epoxy-1-butene and catalyst components;
• wherein the catalyst components comprise (i) a quaternary phosphonium iodide having a total of about 16 to 60 carbon atoms and the formula:
• ##STR21## and (ii) an organotin (IV) compound having the formula:
• (R.sup.7).sub.3 --Sn--I
• wherein each R.sup.6 substituent is independently selected from alkyl of up to about 20 carbon atoms, benzyl, phenyl or phenyl substituted with up to 3 substituents selected from lower alkyl, lower alkoxy or halogen;
• each R.sup.7 substituent is independently selected from alkyl of up to about 12 carbon atoms, benzyl, 2-methyl-2-phenylpropyl, phenyl or phenyl substituted with up to 3 substituents selected from lower alkyl, lower alkoxy or halogen;
• and the mole ratio of (i):(ii) is about 10:1 to 0.1:1;
• the concentration of the catalyst system in the reaction zone liquid is maintained at about 50 to 95 weight percent, based on the total weight of the reaction zone liquid;
• and the liquid phase of the reaction zone is maintained at a temperature of about 80.degree. to 120.degree. C.