Process to recover 3-methyl-but-3-en-1-ol

1. A method for recovery of 3-methyl-but-3-en-1-ol comprising at least the steps of

a) contacting a stream comprising (Z)-3-methylpent-2-ene-1,5-diol, (E)-3-methylpent-2-ene-1,5-diol and 3-methylenepentane-1,5-diol with isobutene and water to obtain a mixture,

b) heating the mixture obtained in step a) to a temperature in the range of ≥200° C. to ≤450° C. to obtain a treated mixture comprising 3-methyl-but-3-en-1-ol; and

c) recovering 3-methyl-but-3-en-1-ol from the treated mixture obtained in step b).

2. The method according to claim 1 , wherein the method is a continuous method.

3. The method according to claim 1 , wherein the steps a) to c) are carried out simultaneously.

4. The method according to claim 1 , wherein the stream comprises (Z)-3-methylpent-2-ene-1,5-diol, (E)-3-methylpent-2-ene-1,5-diol and 3-methylenepentane-1,5-diol in an amount in the range of ≥75.0 wt. % to ≤99.0 wt. %, based on the total weight of the stream.

5. The method according to claim 1 , wherein the stream comprises (Z)-3-methylpent-2-ene-1,5-diol in an amount in the range of ≥15 wt. % to ≤30 wt. %, (E)-3-methylpent-2-ene-1,5-diol in an amount in the range of ≥15 wt. % to ≤30 wt. % and 3-methylenepentane-1,5-diol in an amount in the range of ≥35 wt. % to ≤55 wt. %, each based on the total weight of the stream.

6. The method according to claim 1 , wherein in step a) the isobutene is added in an amount in the range of ≥75 wt. % to ≤90 wt. %, based on the total weight of the stream.

7. The method according to claim 1 , wherein in step a) the water is added in an amount in the range of ≥5 wt. % to ≤70 wt. %, based on the total weight of the stream according to claim 1 .

8. The method according to claim 1 , wherein the step b) further comprises heating the mixture at a pressure in the range of ≥60 bar to ≤260 bar.

9. The method according to claim 1 , wherein the step c) comprises at least the steps of

A′) separating the treated mixture obtained in step b) into an organic phase comprising at least ≥60 wt. % 3-methyl-but-3-en-1-ol methanol, based on the total weight of the organic phase, and an aqueous phase comprising water and ≤10 wt. % 3-methyl-but-3-en-1-ol, based on the total weight of the aqueous phase; and

B′) subjecting the organic phase obtained in step A′) to a temperature in the range of ≥120° C. to ≤160° C.

10. The method according to claim 1 , wherein the stream of step a) is obtained by a process comprising at least the steps of:

A) reacting 2-methylprop-1-ene and formaldehyde to obtain a mixture comprising at least 3-methyl-but-3-en-1-ol, formaldehyde, methanol, water, (Z)-3-methylpent-2-ene-1,5-diol, (E)-3-methylpent-2-ene-1,5-diol and 3-methylenepentane-1,5-diol;

B) separating the mixture obtained in step A) into an organic phase comprising at least 3-methyl-but-3-en-1-ol, (Z)-3-methylpent-2-ene-1,5-diol, (E)-3-methylpent-2-ene-1,5-diol and 3-methylenepentane-1,5-diol and an aqueous phase comprising water and ≤10 wt. % 3-methyl-but-3-en-1-ol, based on the total weight of the aqueous phase; and

C) subjecting the organic phase obtained in step B) to a temperature in the range of ≥120° C. to ≤160° C. to obtain 3-methyl-but-3-en-1-ol and the stream comprising (Z)-3-methylpent-2-ene-1,5-diol, (E)-3-methylpent-2-ene-1,5-diol and 3-methylenepentane-1,5-diol.

11. The process according to claim 10 , wherein in step A) the temperature is in the range of ≥200° C. to ≤350° C.

12. The process according to claim 10 , wherein in step A) the pressure is in the range of ≥200 bar to ≤300 bar.

13. The process according to claim 10 , wherein in step C) the pressure is in the range of ≥50 to ≤300 mbar.

14. A process for the production of 3-methyl-but-3-en-1-ol comprising the step of combining 3-methyl-but-3-en-1-ol obtained by the method of claim 1 , wherein the stream of step a) is obtained by a process comprising at least the steps of:

A) reacting 2-methylprop-1-ene and formaldehyde to obtain a mixture comprising at least 3-methyl-but-3-en-1-ol, formaldehyde, methanol, water, (Z)-3-methylpent-2-ene-1,5-diol, (E)-3-methylpent-2-ene-1,5-diol and 3-methylenepentane-1,5-diol;

B) separating the mixture obtained in step A) into an organic phase comprising at least 3-methyl-but-3-en-1-ol, (Z)-3-methylpent-2-ene-1,5-diol, (E)-3-methylpent-2-ene-1,5-diol and 3-methylenepentane-1,5-diol and an aqueous phase comprising water and ≤10 wt. % 3-methyl-but-3-en-1-ol, based on the total weight of the aqueous phase; and

C) subjecting the organic phase obtained in step B) to a temperature in the range of ≥120° C. to ≤160° C. to obtain 3-methyl-but-3-en-1-ol and the stream comprising (Z)-3-methylpent-2-ene-1,5-diol, (E)-3-methylpent-2-ene-1,5-diol and 3-methylenepentane-1,5-diol, with 3-methyl-but-3-en-1-ol obtained by the method according to claim 1 to obtain combined 3-methyl-but-3-en-1-ol.

15. The process according to claim 14 , wherein the process further comprises the step of subjecting the combined 3-methyl-but-3-en-1-ol to a purification method to obtain combined 3-methyl-but-3-en-1-ol of a purity ≥98.0 wt. %.