GB1560241A

GB1560241A - Purification of 3,5-xylenol

Info

Publication number: GB1560241A
Application number: GB4201/77A
Authority: GB
Original assignee: Shell Internationale Research Maatschappij BV
Current assignee: Shell Internationale Research Maatschappij BV
Priority date: 1975-04-28
Filing date: 1977-02-02
Publication date: 1980-01-30

Description

(54) PURIFICATION OF 3,5-XYLENOL (71) We, SHELL INTERNATIONALE RESEARCH MAATSCHAPPIJ B.V., a company organised under the laws of the Netherlands, of 30 Carel van Bylandtlaan, The Hague, The Netherlands, do hereby declare the invention, for which we pray that a patent may be granted to us, and the method by which it is to be performed, to be particularly described in and by the following state ment: - This invention, which is a modification of that described in our U.K. Patent Specification No. 1,533,983, relates to a method of purifying 3,5-xylenol which has been prepared from 3,5,5 - trimethyl - 2 - cyclohexen - 1 - one (isophorone).

The U.K. Patent Spedification No.

1,533,983 describes and claims a process for the preparation of 3,5-xylenol which comprises heating isophorone at a temperature from 4500 to 6500C in the presence of a halogen of atomic number at least 17, or an organic compound containing such a halogen.

The 3,5-xylenol thus prepared contains residues of free halogen and halogen-containing compounds. These residues could give rise to corrosion problems, for example, if the product were allowed to come into contact with apparatus made of mild steel. The present invention is concerned with a simple and effective method of removing halogen residues from the 3,5-xylenol.

Accordingly the invention provides a method of purifying 3,5-xylenol which has been prepared by heating isophorone at a temperature from 4500 to 6500C in the presence of a halogen of atomic number at least 17, or an organic compound containing such a halogen, which method comprises contacting the 3,5-xylenol with at least one metal chosen from the group magnesium, zinc, cadmium or the group iron, cobalt, nickel. Preferred metals are zinc, magnesium or iron.

The metal is preferably in a divided form, in particular in finely divided or powdered form. The amount of metal used is generally from 0.01 to 5%, for example 0.1 to 1% by weight of 3,5-xylenol. The particularly preferred metal is zinc.

The method of the invention may be conveniently carried out by heating rhe crude 3,5-xylenol with the metal at a temperature of 1000 to 2000C for a period of 0.5 to 5 hours. The 3,5-xylenol may be separated from the metal by filtration and rhen further purified by distillation.

The invention is illustrated further in the following Examples.

EXAMPLES 1 to 3 The 3,5-xylenol was prepared by heating isophorone at 6000C in the presence of 1% by weight of merhyl iodide as described in the co-pending application 17533/75, Speåfica- tion No. 1,533,983. The crude phenol con tained 0.5% by weight of iodine in both free and combined form.

The metals used in the Examples were: 1. Powered zinc (Billiton 110, av. part.

size 3 micron) 2. magnesium turnings (Merck, Registered Trade Mark, 99.5% pure) 3. powdered iron (Brocacef B.V., Maarsen).

The crude 3,5-xylenol and the metal (0.2 % by weight based on 3,5-xylenol) were heated together for one hour at 1800C under atmospheric pressure. The 3,5-xylenol was then distilled off under a pressure of 10 mm Hg and the iodine content of the purified product was determined. The results are given in the following Table I.

TABLE I Iodine content Example Metal 3,5-xylenol (ppm) 1 Zn 18 2 Mg 87 3 Fe 30 The corrosivity of the purified 3,5xylenol from Example 1 was determined by heating the product with a plate of mild steel in an autoclave at 2500C for 7 days and measuring the amount of metal removed. The corrosivity expressed in mm metal removed per year was obtained for both the liquid and gaseous product and compared with that of the crude 3,5-xylenol. The results are given in Table II below.

TABLE II Corrosivity (mm/year) 3,5-xylenol gas-phase liquid-phase from Example 1 0.01 2.7 crude 0.6 14.0 WHAT WE CLAIM IS: 1. A method of purifying 3,5-xylenol which has been prepared by heating isophorone at a temperature from 4500 to 6500C in the presence of a halogen of atomic number at least 17, or an organic compound containing such a halogen, which method comprises contacting the 3,5-xylenol with ar least one metal chosen from the group magnesium, zinc, cadmium or the group iron, cobalt, nickel.

2. A method as claimed in claim 1, wherein the metal is zinc, magnesium or iron.

3. A method as claimed in claim 1 or claim 2, wherein the metal is in finely divided or powdered form.

4. A method as claimed in any of claims 1 to 3, wherein the amount of metal is from 0.01 to 5 % by weight based on the weight of 3,5-xylenol.

5. A method as claimed in any one of claims 1 to 4, wherein the 3,5-xylenol is heated with the metal at a temperature of 1000 to 2000C for a period of 0.5 to 5 hours.

6. A method as claimed in claim 1, sub stantially as hereinbefore described with particular reference to the Examples.

7. Purified 3,5-xylenol whenever prepared by a process claimed in any one of claims 1 to 6.

**WARNING** end of DESC field may overlap start of CLMS **.

Claims

**WARNING** start of CLMS field may overlap end of DESC **. of the crude 3,5-xylenol. The results are given in Table II below. TABLE II Corrosivity (mm/year) 3,5-xylenol gas-phase liquid-phase from Example 1 0.01 2.7 crude 0.6 14.0 WHAT WE CLAIM IS:

1. A method of purifying 3,5-xylenol which has been prepared by heating isophorone at a temperature from 4500 to 6500C in the presence of a halogen of atomic number at least 17, or an organic compound containing such a halogen, which method comprises contacting the 3,5-xylenol with ar least one metal chosen from the group magnesium, zinc, cadmium or the group iron, cobalt, nickel.