Reacción #56361

Ecuación de reacción

1-ethoxy-1,3-pentadiene

glyoxal

glyoxal hydrate

pyran

phosphorus pentoxide

→

3,6-dihydro-3-methyl-6-ethoxy-2H-pyran-2-carboxaldehyde

Condiciones de reacción

Tratamiento posterior

1. 1
   Temperaturaby heating
2. 2
   workup.ADDITIONa mixture of 8.0 g
3. 3
   OtroThe liberated monomer was bubbled (argon stream) into 4.8 g
4. 4
   Otroat 120°
5. 5
   Temperaturathe solution was heated at 120° for an additional 45 minutes
6. 6
   workup.DISTILLATIONDistillation
7. 7
   Otroafforded 1.32 g

Procedimiento

Monomeric glyoxal was generated by heating a mixture of 8.0 g. of glyoxal hydrate (0.117 mol. of monomer) and 48.0 g. of phosphorus pentoxide over a gentle flame over 35 minutes. The liberated monomer was bubbled (argon stream) into 4.8 g. (0.04 mol) of 1-ethoxy-1,3-pentadiene (purity 92.3%) at 120°. After all the monomer had been generated, the solution was heated at 120° for an additional 45 minutes. Distillation afforded 1.32 g. of the pyran (b0.07 =56°, purity 91%) and 1.86 g. of recovered diene (yield based on diene-32%, based on glyoxal=6.6%).

Fuente