DD204474A1 - REMOVAL OF GUAJACOL FROM CRESOL MIXTURES - Google Patents

Abstract

Process for the removal of guaiacol from cresol mixtures by fractional distillation in the presence of a distillate boiling above the cresols at a pressure of 0.133 to 13.33 kPa. The distillation adjuvant used are compounds which contain alcohol and ether groups, for example diethylene glycol and triethylene glycol. The process increases the quality of the meta-para-cresol mixtures obtained from brown coal phenols and ensures the production of a high quality guaiacol fraction for further use.

Description

237977

VEB Leuna-Werke Leuna,

"Walter Ulbricht"

LP 81 138

Title of the invention

Removal of Guajacol from cresol mixtures

Field of application of the invention

The invention relates to a process for the removal of guaiacol from cresol mixtures with the aim of increasing the quality of the end product Me.ta-para-cresol and to recover the removed guaiacol as a high-percentage guaiacol fraction.

In the distillative workup of carb-öchemischen Rohphenolölen »which are obtained from various lignite derived products containing the final meta-para-cresol mixtures containing 2-methoxphenol - also known as guaiacol - as caused by the boiling points major impurity in the concentration range of 2 to 15 percent by mass , This contamination disturbs the subsequent processing of meta-para-cresol to cresol-pormaldehyde condensation resins, limits the desired high content of meta- and paracresol and thus the use value, this .. final product from the Garbochemie.

2379 77 4

Characteristic of the known technical solutions

The distillative workup of Rohphenolölen and cresol mixtures to meta-pars-cresol-rich fractions is known per se; In this case, the ortho-cresol and the xylenols obtained can be separated on the basis of the boiling point differences of meta-para-cresol (A. Dierichs, "R" Kubicka "phenols and base deposits and extraction", Akademieverlag Berlin, 1958, p 285 ff and 313 ff.). However, if the crude phenol oil and the cresol mixture contain guaiacol, as is customary in lignite products as a consequence of the lignin content of lignite, removal of the guaiacol due to the low boiling point differences between guaiacol and meta-para-cresol of only 3 K with technically economically justifiable effort distillative way not possible. Therefore, the technical meta-para-cresol mixtures prepared from GDR lignite raw materials contain between 10 and 15% by weight of guaiacol. The content of valuable meta-para-cresol is even at high distillation costs and taking into account other: 'impurities at a maximum of 85 percent by mass. On the one hand, this limits the use value of meta-para-cresol, on the other hand, valuable guaiacol itself is lost as a raw material. Methods for the removal of guaiacol on a purely distillative basis are not known, however, in the relevant literature. Methods and methods for removing guaiacol by its chemical conversion into separable products mentioned.

This is how a procedure is demanded. in the case of the alkylphenol ether, for example guaiacol, from such a tar fraction together with the cresols, by treatment with UaOH, into the sodium salts, then dehydrated and then brought into contact with air and water vapor. In this case, the alkylphenol ethers are selectively cleaved and the cleavage products are separated from the other phenols and cresols (US Pat. No. 2,393,700). This process is not just technolo-

237977 A

very complicated but requires a high amount of chemicals and energies. The required effects are not guaranteed.

Guaiacol can be cleaved by a known method by gaseous chlorine or hydrogen bromide in. Presence of aromatic amines at 180 to 200 ⁰ C and cleaved into the removable catechol (US Patent 2,100,228). From the described method is not apparent whether it is also applicable in admixture with cresols. In addition, expensive chemicals are also irreversibly required here, and complex and corrosion-resistant guaiacol cleavage equipment and its processing are necessary.

The same disadvantages also have a method for saponification of guaiacol with aluminum chloride (DRP 707 18).

In a paper by DV Tishchenko et al., (Gidroliz Lesochim., Prom., 3, 6-8 / 1956 /), the separation of guaiacol from a mixture of phenols / cresols boiling between 180 to 212 G, obtained in the processing of lignocellulosic products, is described were. Here, the Guajacolentfernung should be achieved by the formation and separation of Magnesiumguajacolate. However, such a method is not technically applicable and does not 'ensure the desired degree of purity of the meta-para-cresol.

Furthermore, a method for the hydrolysis of guaiacol in. .. Mixture with other phenols derived from wood products, known, after which the Guajacolspaltung by heating with 10 to 20 % jitzkali at 270 to 285 ⁰ C is carried out. Also, this method of Guajacolentfernung by chemical conversion into separable products is technologically complex and 'requires a large amount of caustic potash as well as a complex ÄufarbeitüngstechnOlogie for cleaning the target

237977 4

Products (D. Y. Tishchenko et al., Zhur., Priklad, Khim., 29, 1447-1449 (1956)).

Finally, it is known to remove guaiacol by vapor phase hydro-Iyse at 500 to 550 ⁰ G in the presence of water vapor and phosphoric acid Pestbed catalysts in separable products. Despite a high expenditure on equipment, the implementation of the Guajacols is at most 65% »in addition, lifting reactions to inferior products, so that the effectiveness of this method is low (VA Shishkin, DV Tishchenko, Isv. Vysski. Üchebn Zavedeny, Lesn. Zh. 5) 156 to 159 (1964), d. 8 (1), 144 to 147 (1965), d. 13 (2) 111 to 115 (1979))

Object of the invention

The aim of the invention is to improve the utility of the meta-para-cresol mixtures and their quality while increasing the content of meta-para cresol contents.

Explanation of the essence of the invention

The invention has for its object to increase the quality of the meta-para-cresol mixtures by the removal of the guaiacol from technical Kresolgeinischen means of a simple, suitable process control and to win the removed guaiacol as an enriched guaiacol fraction.

This object is achieved in that it contains the contaminated with guaiacol cresol mixture in the presence of a higher than cresol and guaiacol boiling distillation adjuvant containing alcohol »and Sthergruppen as functional groups, in the ratio cresol mixture to distillation aid of 1; 0.5 to 1: 20 distilled at a pressure of 0.133 to 13.33 kPa, using as a low-boiling fraction

237977 4

a mixture enriched with guaiacol with ortho-cresol and a lower content of meta-para-cresol, followed by an extraction with a meta-para-cresol content of more than 95% by mass and a guaiacol content of less than 1% by weight and finally the distillation excipient is attributed to the process.

The distillate used is preferably diethylene glycol or triethylene glycol.

Conveniently, the ratio of cresol mixture to distillate aid is 1: 1 to 1:10.

It is advantageous if the distillation is carried out at a pressure of 0.3 to 6.7 kPa. · .. ..

It is an advantage of the overall process if the fraction which is lighter than meta-para-cresol and is rich in guaiacol is enriched by further fractional distillation to a guaiacol content of more than 50% by mass.

The process according to the invention ensures the production of a high-quality meta-para-cresol mixture of cresol mixtures in which the guaiacol content is less than 1% by mass and the meta-para-cresol content is more than 95% by mass. This meta-para-cresoT mixture obtained in this way has substantially improved "utility values" compared with the starting cresol mixture, and in particular the production of high-quality cresol-ij-paraldehyde condensation resins.

The yield of this high-quality, meta-para-cresol is up to 97 percent by weight, based on the meta-para-cresol present in the Einsatzresol. Distillation Guajacolentfernung under technical conditions without Destillati is onshilfsstoff or only at unacceptable technical, economic cally-high effort possible * The Eff _described: is e.kt, while _üb; he, as ... che ^e i ^{e e}

simple technology on a distillative basis and through

237977

set of an easily accessible and industrially produced distillation adjuvant, preferably diethylene glycol or Eriethyienglycol. In the method according to the invention, the losses of this additional component are very low, since a frequent recycling of the additional component together with fresh cresol mixture is possible without the effect is reduced. Technical cresol mixtures of very different composition can be used in the process. The enrichment of the heta-para-cresol components and the removal of the guaiacol is also achieved when the technical Ausgangscresolgemisch a relatively high content of ortho-cresol or a certain xylenol content is present. Another effect of the process according to the invention is also that the content of the impurity o-ethylphenol present in the technical starting cresol mixture is likewise reduced, since this impurity partially enters into the guaiacol fraction.

The process according to the invention can be used both in continuous and discontinuous distillation technology, depending on the existing technical conditions and the conditions of the apparatus. In the case of a continuous process design, the distillation assistant is advantageously not added directly to the Einsatzresol mixture, but added to the column of a first column above the Cresoleinlaufes. In this first column, the fraction rich in guaiacol, in a second column, the meta-para-cresol fraction, each as a distillate, are removed, while the distillation assistant is returned as the bottom product of the second column in the first column.

As the examples show, the concentration of guaiacol in the guaiacol fraction is increased by a suitable column or by multiple use of this fraction in the process to over 50 percent by mass, so that this fraction

can be used as a raw material for the production of the economic catechol or directly for pharmaceutical purposes. The separation of ortho-cresol and phenol from the guaiacol fraction is easily and in a known manner possible, since the boiling point differences of these components are sufficiently large,

embodiments

example 1

500 g of a technical Kresolisomeren mixture, which was prepared by distillative workup from lignite-derived Rohphenolöl, the analytical composition

o-cresol 3.7 %

m- + p-cresol 81.1 %

Guajacol 11.2%

other phenolic and non-phenolic substances 4 »0 %

are mixed with 2,500 g of diethylene glycol. The distillation of this mixture takes place at a vacuum of 3.33 kPa and a reflux ratio of 1:20 in a batch distillation apparatus with a 1 m long packed column filled with metal spirals. The two transition between 100 ⁰ C and 112 ⁰ C head temperature. Fractions have the following analytical composition:

1st Fraction 2, .Fraktlon. o-cresol 8.4%

m + p-cresol 62.7 %: - 97.2%

Guajacol 24.7 % 0.6 %

other phenolic and

non-phenolic substances 4.2 · $ 2.2 %

amount used 220 g 270 g

The diethylene glycol residue contains 0.2 % m / p-cresol and 0.2 % other phenolic and non-phenolic substances »

237977

The resulting berechnete.Ausbeute of m / p-cresol in the second fraction, based on the m / p-cresol GehaIt in the feedstock is _64.7%} ·

Repeated distillation of the 1st fraction with the residue under the conditions of 1, distillation gives the following products:

1st fraction (guaiacolane-enriched fraction) combined 2nd fractions (m / p-cresol fraction) 20.3 % 0 % 14.8 % 97.0 % 58.5% 0.7 % 6.4 % 2.3 % 91 g 399 g

o-cresol

m / p-cresol

guaiacol

other phenolic and non-phenolic substances

incurred quantity

The composition of the residue has not changed,

The calculated therefrom yield of m / p-cresol in the in / p-cresol fraction, based on the m / p-cresol content in the technical Kresolisomeren mixture used, is 95.4% ·

Example 2

A technical cresol isomer mixture of the analytical composition as in Example 1 is continuously distilled with di-ethylene glycol.

The distillation apparatus used consists of a column bottom, the stripping section, the amplifier section, the top of the column and 3 metering pumps * Amplifier and stripping section are packed columns filled with metal spirals.

The technical Kresolisomeren mixture is introduced in a flow rate of 15 g / h between the amplifier and stripping section, the diethylene glycol in a flow rate of 150 g / h in the amplifier part. The distillation is at a

237977 k

Yakuum of 3.33 kPa operated at a reflux ratio of 1:20 *

At the top of the apparatus, 25 g of Hit Guajacol-enriched product were taken off during a 10 hour distillation.

The residue of the distillation is introduced between the booster and stripping section of a 2nd continuous distillation apparatus, which corresponds in structure and the distillation conditions of the 1st distillation apparatus.

At the top of the second apparatus, 120 g of m / p-cresol fraction are removed during a distillation lasting 10 hours and 1505 g of diethylene glycol are removed from the bottom of the column.

The products obtained have the following analytical composition:

Guajacol Group m / p-cresol practice Residue 22.2 % - 62.4 % 1.0 % 11.6 % 95, a % 0.25 3.8 % 3.2 % 0.08 99.7

o-cresol guaiacol m / p-cresol

other phenolic and non-phenolic substances 3.8 %

diethylene glycol

The calculated from this as in Example 1 yield of m / p-cresol is 94.5 %.

Example 3

500 g of a technical Kresolisomeren mixture of the analytical composition as in Example 1 are mixed with 500 g Trie thylenglycol.

The distillation of this mixture takes place in the distillation apparatus and under the conditions described in Example 1 »

237977 4

The passing fractions and the sump have the following analytical composition:

1 , Fraction (276.3 g) 2nd fraction (209 g) Rucks (514, 7 g) o-cresol 6.7 % - m / p-cresol 70.8 % 96.2 % 1.8 % guaiacol 19.5 % 1.0 % other phenolic and 3.0% non-phenolic substances 2.8 % 1.1 % triethylene 97.1 %

The resulting calculated as in Example 1 yield of m / p-cresol is 49.6 % <, The first fraction is distilled again with the residue, as described in Example 1, to increase the yield.

Example 4

500 g of a technical cresol mixture of the analytical composition as in Example 1 are mixed with 2,500 g of diethylene glycol.

The distillation of this mixture is carried out at a vacuum of 6.66 kPa and a reflux ratio of 1:20 in the distillation apparatus described in Example 1.

The two 116 between ⁰ G and 123 ⁰ C head temperature continuous fractions and the bottom have the following analytical composition:

o-cresol m / p-cresol guaiacol

1st fraction (241.6 g) 2nd fraction (218.4 g). Rear stand (2540 P-) 7 7 & - - 68.5 % 95.4 % 1 ο oi 22.5 % 0.8 % -

237977

other phenolic and non-phenolic substances

diethylene glycol

1st fraction (241.6 g)

1.3 %

2nd fraction (218.4 g)

3.8 %

Residue (2540 g)

0.3 % 98.5 %

The resulting calculated as in Example 1 yield of m / p-cresol is 51.4 % · The yield can be further increased if the 1, fraction is worked up again together with the residue under otherwise identical distillation conditions. The final yield of the recoverable m / p-cresol, based on the cresol contained in the starting material, can thus be increased to about 95%.

Claims (4)

Erfindungsanspruoh 1. Removal of guaiacol from cresol mixtures by distillation, characterized in that the cresol mixture contaminated with guaiacol in the presence of a distillation higher than meta-para-cresol and guaiacol distillation »
excipient containing alcohol and ether groups as functional groups in a ratio of crescene mixture to distillation aid of 1; 0.5 to 1: 20 distilled at a pressure of 0.133 to 13.3 kPa, wherein as a low-boiling fraction enriched with guaiacol mixture with ortho-cresol and a lower content of heta-para-cresol, then a fraction with
a meta-para-cresol content of more than 95% by mass and a guaiacol content of less than 1% by mass
decreases and finally the distillation excipient as
The residue is returned to the process. 2. Removal of guaiacol according to item 1, characterized in ^that net is used as a distillation aid Diet.üylenglycol or triethylene glycol. 3. Removal of guaiacol according to items 1 and 2, characterized in that the ratio of cresol mixture to distillation aid is 1: 1 to 1:10. 4. removal of guaiacol according to item 1 to 3, characterized in that the distillation at a pressure of
0.3 to 6.7 kpa is performed *