DE3146868C2 - Process for the distillative separation of side-chain chlorinated alkyl aromatics and their derivatives chlorinated in the core for the purpose of making them pure - Google Patents

Abstract

Pure side-chain chlorinated alkyl aromatics are obtained by distillation of chlorination mixtures of the alkyl aromatics with chlorine contents between 4 and 68% by weight of chlorine in the side chain or their derivatives chlorinated in the core by fractional distillation at bottom temperatures of 100 to 180 ° C and reduced pressure of 1 to 120 mbar in packing -Columns made of glass or ceramic.

Description

a) See the starting materials to be used for separation:

Mixtures of any composition with chlorine contents between 4 and 68% by weight of chlorine in the side chain, produced by side chain chlorination of toluene or xylene or their derivatives, which are chlorinated in the core,

b) fractional distillation in a packed column at bottom temperatures of 100 to 180 ⁰ C and a reduced pressure of 1 to 120, preferably 6 to 30 mbar,

c) Use of column packings made of glass or ceramic material (the latter is of such a nature that no Components with a decomposition effect on starting materials and end products are released den can) who

el) an orderly one, moving steadily in all spatial directions have a repeating hollow structure (avoiding vertical Seal the hollow channels inside the column packing and ensure that it is sealed Connecting the structural elements to the column jacket), wherein

c2) di ^ space filling of the column packing 10 to 30%, so that

c3) as a result of this packing, the pressure drop per theoretical plate is less than 1 mbar in the entire operating range,

Exclusion of traces of heavy metals the execution of the fractional distillation.

2. The method according to claim 1, characterized that one next to the Haunt faction accruing secondary fractions again in accordance with the process into pure substances and secondary fractions Distillation separates or through reaction with chlorine in higher or completely in the side chain transferred to chlorinated compounds.

The chlorination of xylenes and toluenes under light catalysis proceeds according to a radical mechanism, whereby the selectivity is low and

Xylenes

Mixtures of chlorinated compounds are obtained. Their components can include the substances I to XXXII be:

X 0 1 2 3 0 2 3 3 Y 1 1 1 1 2 2 2 3 0- I. Il III IV V VI VII - m- VIII IX X Xl XIi XIII XIV XV P- XVI XVH XVIlI XIX XX XXI XXII XXIII

CH ₁ -. ,, Cl ₁

Γ _{χν | ν} '"
XXMl XXMlI XXiX -Ci XXX XXX! X X X Vlonochlprtoluolc χ 'j m- V

With the exception of the six-fold chlorinated o-xylene in the side chain, which is not due to spatial reasons arises, and the improbable on one methyl group triple, on the other non-chlorinated Xylenes, each three to five of the conceivable substances form the typical chlorination mixture of a xylois or Chlorotoluene. Only arise with perchlorination VH, XV, XXIII, XXVI, XXIX and XXXII as approximately pure substances.

There is a need for the less widely chlorinated compounds as intermediates. The separation These substances from the chlorination mixtures is difficult, especially since the substances are extremely corrosive and are thermally unstable and tend to condensation reactions (GB-PS 14 10 474). The same applies to corresponding essentially chlorinated derivatives.

In the prior art, various measures are taken without affecting others Mixtures of substances lead to pure substances or significantly increased enrichment:

Additions of third-party substances in the chlorination cause only slight increases in selectivity.

Crystallization processes require multiple crystallizations and give low yields with little satisfactory purity.

Distillative separation processes are difficult and often result in product mixtures: According to GB-PS 14 10 474, α-chloro-p-xylene (XVI) in packed columns in the presence of, for example, amines is from a mixture with contents of “A'-dichloro-p -Xylene (XVII) separable. According to the published Japanese patent application 54/125 628 (1979) (Banyu Pharmaceutical Co.) “AA'-trichloro-p-xylene (XVIII) can be obtained by distillation. Na ^ h BE- ^ S 5 90 772 one obtains o ^ '- dichloro-p-xyloi (XVJI) from chlorination mixtures only as an enriched residue product

With all distillation processes it does not succeed with acceptable technical effort. Products more sufficient To create purity. Only mixtures with a wide boiling range and more or less higher Enrichment of the desired component compared to the chlorination mixture is available. So far If third substances have been added, these must be removed again. There is no single one with required purity Winnable fabric. In general, a subsequent crystallization process is therefore necessary for purification.

In particular, the distillation of the more highly chlorinated compounds, such as VI, XIH or XXI, which only show slight differences in volatility, have not yet been described.

The task was therefore to remove the individual components of mixtures at a reasonable cost to separate side-chain chlorinated alkyl aromatics in good yields as products of sufficient purity and to recycle the by-products that occur in a meaningful way.

The subject of the invention is therefore the method indicated in the preceding claims for the separation by distillation of side-chain chlorinated alkyl aromatics and their derivatives chlorinated in the core for the purpose of pure representation of the same.

The starting materials are the xylenes and toluenes chlorinated in the side chain and their chlorinated core Derivatives with one to four nuclear chlorine atoms in the case of xylenes and up to five nuclear chlorine atoms Toluene with a chlorinated side chain.

The respective degree of chlorination has from 4 to 68% by weight of the alkyl aromatic compound chlorinated in the side chain to be guided by the target product in such a way that as high a proportion of the target product as possible in the Feedstock is present, but the feedstock can also be the lead or tail of a preceding one Rectification can be chosen.

When calculating the degree of chlorination of the side chain, chlorine remains as a substituent of the aromatic Kerns, if available, e.g. B. in the mixture of the side-chain chlorinated p-ChlorotoluoIs, disregarded

The column packings should consist strictly of materials, the heavy metals not due to the effect of corrosion of chlorinated alkyl aromatics. The material is then tantalum, but in particular ceramic materials required.

That corresponds to heavy metals, even in traces

should generally be excluded, so that in to

Distilling mixtures of heavy metals or their compounds only in amounts of less than 0.5 ppm, calculated as metal.

In addition, the ceramic material of the column packing must not contain such metals or Release meta-oxides that, like aluminum in particular, for Lead formation of Lewis acids.

The alkyl aromatics chlorinated in the side chains have a disproportionately stronger tendency than other chlorinated ones Hydrocarbons for the formation of condensed aromatics from two or more molecules with splitting off of hydrogen chloride, which resulted in high yield losses so far, the distillation through "gel formation" was made difficult and the vacuum collapsed due to the gaseous hydrogen chloride.

Conversely, an undiminished, sustained vacuum is the unmistakable sign that hydrogen chloride is present or other decomposition products do not occur and neither the condensation by Lewis acids nor the catalytic decomposition takes place through traces of heavy metals or their compounds.

As far as is known, the side kct- ■ "> is used in the distillation Chlorinated alkyl aromatics for the first time in the context of the present invention, the condensation and catalytic Decomposition of the products can be avoided and thus for the first time the reduced pressure from 1 to 120mbar with vacuum rectification in technical 4> usably sustainably.

Surprisingly, it was found that not only glass that forms such heavy metals and Lewis acids Does not contain metals, but also ceramic materials in which heavy metals and given > "If aluminum is definitely contained, it can be used as the material for the column packing.

Obviously, it is only necessary to use a ceramic material, its oxidic or silicate Components by annealing, sintering or similar treatments at high temperatures create a structure z. B. had received in the manner of sintered ceramics, from which components with a decomposing effect during the rectification cannot be released onto starting materials or products.

bo to be particularly suitable ceramic materials from 10-40 wt .-% ZrO ₂ and 90-60 wt ° / o SiOj, preferably 15 to 22 wt .-% ZrO ₂ and 80 to 60 wt proven ° / o SiO ₂ , which analytically Fe ₂ O ₃ , Ni and Mn can each have amounts of about 0.01% <> 5 and, if appropriate, can also contain smaller or larger proportions of Al ₂ O ₃ . It is surprising that ZrO ₂ as oxide or optionally as silicate in annealed or sintered form does not lead to the formation of

Lewis acids give cause Likewise, contents of heavy metals are part of the oxidic resp. silicate ceramic harmless, unlike traces of heavy metals in impurities on the surface, which become noticeable during the first use and through the first use or, if applicable treatment with hydrochloric acid can be removed.

To achieve the low pressure drop of less than a mbar p ^r o theoretical stage of separation in the entire operating range required column packings which have an ordered, continuously recurring hollow structure in all three spatial directions.

In these "ordered" column packings, the space should only be 10-30%, preferably 10-20%, be. It is important that the arrangement of the ceramic structural elements in the column packing does not has vertical hollow channels inside and tightly adjoins or sealed the inside of the Koionnenmantel will.

The column packing expediently therefore consists of several preferably arranged one above the other similar part packs in which the 5 * structural elements connected to a single interspersed with cavities. With smaller columns they have Partial packs preferably have the external shape of cylinders or cylinder segments, or optionally Disks with a diameter of about 2: 1 to 1: 4, preferably 1: 1.5 to 1: 3.5 in relation to height, for larger ones Columns can have the shape of layers or strips in addition to the above-mentioned columns that are arranged close together. The packs always have the contact surfaces with the column wall one or more sealing strips, made of z. B. Asbestos cord or strip or from rings or strips of fluoropolymers inert to chlorinated alkyl aromatics and horizontal are arranged so that rising vapors of the distillate and the reflux from the column wall in inside the pack.

Ceramic column packings, with the outer shape of especially cylinders, are very preferred or, if necessary, disks or strips, in their ordered, continuous structure inside webs, strips, Ribbons, rods or coils at an angle of 20 to 70 ° to the vertical so parallel in layers to each other are arranged so that karate is at the same angle of inclination λ to the vertical, which are arranged into vertical layer planes, on which, in the horizontal view, a Layer plane with channels of the same angle of inclination α in the other direction follows.

In the case of the webs or strips, there are therefore two successive layers in the manner of a grid one on top of the other, so that in view perpendicular to the layer planes, to the parallel channels of a layer the parallel channels of the next layer follow at an angle of 2 χα to the channels of the first layer and each channel of one layer has regular connecting openings to channels of the next layer and the bars or strips at all points of contact with bars or strips of the next layer one Having connection.

The rising gas flow is therefore forced to rise at an angle to the vertical and is caused by the connecting openings distributed over the next channels, the backflowing condensate would be the same is distributed and evenly over the entire inner surface of aEier structural elements of the column packing is distributed and forms a maximum contact area with the gas flow. The equilibrium of distribution the substance can thus adjust itself very quickly, specifically depending on the altitude in the column. In addition, the surface of the pack can be increased further by adding the ridges or strips Have profile z. B. triangular, trough-shaped, cross-shaped Represent cross-sections.

Furthermore, the ceramic materials of the ίο bars or strips can become adhesive after firing Order of ceramic grains of the same or different types received, then arranged to the packs and re-sintered or fired, creating the ceramic grains at the contact points of the webs or strips melt or soften and after cooling a permanent firm connection cause the webs or strips at all points of contact, so that each packing element is a single represents hollow structure traversed by channels, which can be easily handled.

In addition, the firmly sintered ceramic grain significantly increases the inner surface; the hollow structure.

Ordered, repeating structures of the column packing are, however, also intersecting Glass rod profiles or fiberglass bundles possible, with connections between the profiles z. B. by coating with silanes as well as enlarged internal surfaces by etching, melting inert glass dust or application of silanes are preferred. No matter what internal structure the Have column packings, it is very decidedly necessary according to the process that the entire Coion pack or each part pack an ordered one that is continuously repeated in all spatial directions Have hollow structure. A space filling of only 10-30% of the column packing is also required through the solid material of the webs or strips, so that 90 to 70% free space remains.

The partial packs are expediently placed one on top of the other in such a way that none of the Continue channels from the next pack in the same direction.

It is also useful in such ordered column packs that the diameter of the webs 4 * or stripes in the range of a few mm, while the length per se is not limited. * Make sure the bars have a sufficiently large angle in relation to the vertical is chosen.

However, the height of the sub-packages or layers expediently does not exceed about 20 cm.

In the case of cylindrical part packs, the diameter can expediently be 1: 0.5 to 1: 3, especially 1: 1 to 1: 2.5.

The angle of the hollow channels of -5 about 30 to about 60 ° with respect to the vertical is very important.

All materials used for the column packing must be at operating temperatures of up to 180 ° C be constant.

Since the decomposition temperatures of the starting materials *> o are 150-190 ° C, these temperatures are allowed be exceeded neither in the still nor in the column. On the other hand, the boiling points are especially the high chlorine content 6-20 mbar in this temperature range. t "It is therefore surprising that according to the present Invention e, 'first a vacuum rectification, d. H. a vacuum distillation with reflux of a selected amount of top condensate in the column at all

is possible and that any decomposition during rectification is so completely avoided that vacuum rectification at all and for the first time the separation of substances and the pure representation of the individual substances with purities of over 93, mostly well over 96% was possible.

The pressure is therefore between 1 and 120 mbar. preferably between 6 and 30 mbar.

It was very surprising that the pressure drop per theoretical separation unit was not as in conventional Separation units depend on the column diameter.

The temperature range between evaporation. Rectification and condensation are very low, for example with ", a'-dichloro-p-xylene (XVIII) only barely 50 ^° C. Since, on the other hand, a minimum number of theoretical separation stages are required to achieve a product unit of about 98%, the latter in the case the separation of XVII and XVIIII is 22, a considerable temperature gradient over the length of the column, caused by the pressure drop in the column packing with the required separation efficiency, is to be expected.

To achieve the high specific separation efficiency within a narrow working temperature range, can only be achieved with column packings of low pressure loss per theoretical plate; will. Hence the low volume of space, which is ordered and repeated in all spatial directions The hollow structure of the column packing is of great importance. to pressure losses of only 0.1 to 1 mbar each theoretical separation stage to achieve.

Comparable operating conditions result for each theoretical separation stage according to Winnacker / Küehler. Chemical Technology. Volume 7, Carl Hanser Verlag, Munich 1975, pages 199-203, with bell and sieve trays 2 to 8 mbar and for random packings (Raschig rings *), Pall rings *). Berl saddles) 1 to 6 mbar. so that due to too high temperature gradients in the dew Side-chain chlorinated alkyl aromatics then decompose occurs.

The present invention is therefore a solution to a very long-standing problem, also with measures the success of which could not be expected from the knowledge of the state of the art.

By using ordered column packings, it is possible, within the technical framework, to use the Components I to XXXII can be obtained in pure form from their mixtures by rectification.

The ceramic material of the packing is resistant to the working materials - after a few hundred Operating hours, no material erosion could be determined - and also does not lead to any decomposition of the Substance itself.

Likewise, no contamination of the packing material, for example through growths, was observed.

The mode of operation can be continuous or discontinuous. The former is preferred used because the regulation of the column is simpler. In addition, the operating content can be started Keep the substance significantly lower than in batch operation. The extraction of a component as a The pure substance is processed in batch operation using known processes by removing the flow and the main flow (desired product) and wake at the top of the column, in continuous operation by removing the Material flows from the top and bottom in at least two

*) protected names.

Passes, with forerun. The main run and, if necessary, the follow-up run are removed one after the other at the head, or by simultaneous removal of the pre-run, main run and, if necessary, follow-up from the heads of made at least two columns.

If several components are to be obtained, several main runs can be made accordingly be removed. The product purities depend on the degree of difficulty of the separation for which the Relative volatility is a measure, between 90 and 99.9%, of the yield, given as the fraction of the recovered of the total amount of product available, is / between 85 and 98% of the material available.

Pre-run and post-run, the latter if necessary after prior cleaning by flash distillation, can be carried out further chlorination with elemental chlorine with light catalysis according to that described at the beginning Process in higher side-chain chlorinated mixtures of derivatives of xylenes or chlorotoluenes or also in the compounds VII, XV, XXIII chlorinated completely or almost completely in the side chain, XXVI, XXIX and XXXII are transferred.

The purities and yields from re-chlorinated substances are not below those values that result from One-time chlorination of the xylenes and chlorotoluenes to the products mentioned can be achieved.

Sonv.t are, also for the first time, unusable By-products of the rectification process through conversion into usable products of a meaningful one Recycling supplied.

By-products, usable auxiliaries or unusable material residues fall in the present Procedure not on. The amount of residue is extraordinary as a result of the avoidance of decomposition small.

For the first time, technically or at all, a number of substances from the chlorination mixtures in available in pure form or in previously unknown purity.

The purity of the products can be determined by the height of the column, i.e. H. the number of theoretical trays, by Repetition of the rectification with certain fractions with high contents of the target product and further usual measures can be increased. The purities of the main fractions given in the examples must therefore not be understood as maximum purity values that can be achieved in accordance with the process.

The separating elements A of Example 1 and the separating elements B of Example 7 are cylindrical part packs placed one on top of the other with a ratio of diameter to height of approximately 1: 1.2. The ceramic material contains, inter alia, about 18% by weight ZrO ₂ and about 79% by weight SiO ₂ . The cylinders consist of vertically adjacent layers of successive, parallel corrugations (similar to the type of corrugated iron), but the corrugations run at an angle of about 25 ° C to the vertical, whereupon a similar undulating layer with the same inclination to the Vertical but in the other direction follows

The channels, inclined at the same angle, have the cross-section of a triangle with strongly rounded ones Corners. All contact points are firmly sintered to one another by means of powdered ceramic grains. In the Column packing with a nominal width of 30 mm, there are 6 to ο inclined channels in view of the cylinder diameter, accordingly more for the packing with a nominal width of 70 mm (example 7).

In the following examples, column packings used with 12 to 14 vol .-% space filling.

Example I.

5.58 kg of a mixture obtained by side chain chlorination of 3.34 kg of o-xylene with the following composition:

Λ-chloro-o-xyloUI) 16.14% by weight

«A aichlor-o-xylene (V) 7.68% by weight

ajt-dichloro-o-xylene (ll) 54.00% by weight

«AA'-trichloro-o-xylolilll) 18.32% by weight

«,«. «',«' - Tetrachloro-o-xylene (VI) 1.49% by weight

Other components 2.37% by weight

are separated in batches in the rectification column described below.

A heatable vacuum fractionating column of 1 m is attached to a heatable still with a capacity of 7 l Height and 30 mm diameter attached, the interior with the cylindrical dividing elements A is equipped with a height of 16 cm, which, lying one above the other, occupy the entire interior of the column and 6 to 8 theoretical plates (trays) correspond. The top closes with a thermostat operated dephlegmator with return divider. To take up the product running off the head is a Template with changing device for vacuum operation available. At a head pressure of 20 mbar, one Gas loading of 2.15 kg / h and a reflux ratio of 10: 1, the head temperature increases during the Rectification process from 86 to 123 ° C, the temperature ies The contents of the bladder gradually increased from 125 to 141 ° C.

The pressure difference between the head and the bladder is below 1 mbar. The separation results are in the summarized in the following list:

component Composition [% by weight] Main up Nachiäuf leader _ _ I. 56.20 1.08 0.19 V 28.47 97.47 10.98 II 14.88 1.09 81.46 III 0.07 - 2.41 IV - 0.36 4.96 Other 0.38 2.69 1.23 Quantities [kg] 1.52

The 2.69 kg of II obtained, with a melting point of 55 ° C., correspond to a rectification yield of 87%. Of the Residue of 0.07 kg, (1.25% by weight) is low.

Decomposition phenomena with elimination of hydrogen chloride are not observed, likewise no assignment of the ceramic separating elements. Lead and lag result, separately or together Treated exhaustively with chlorine under the conditions of the side chain chlorination, 4.28 kg of "aaa'a'-pentachloro-o-xylene (VII) a purity of 98.7% according to gas chromatographic analysis. The advance can can also be chlorinated to the same degree of chlorination as the original chlorination mixture and then gives the results given with the same fractionation.

Example 2

6.53 kg of a mixture by side chain chlorination of 2.84 kg of o-xylene was obtained with the

following composition

a, «'- dichloro-o-xylene (ll) 1.76% by weight

«,«, «'- trichloro-o-xylene (III) 29.34% by weight

α, Λ, α, Λ'-tetrachloro-o-xylene (IV) 3.22% by weight

ΛΑΛ ', Λ'-tetrachloro-o-xylene (VI) 56.14 wt. O / o

Λ, Λ, Λ, α ', α'-pentachloro-o-xylene (VII) 8.39% by weight

Other components 1.15% by weight

are subjected to rectification in the apparatus described in Example 1. Head pressure: 8 mbar. Gas load: 2.1 kg / h. Return ratio 10: 1. The head temperature increases from 106 to 14PC and the temperature of the bubble contents from 133 to 158 ° C gradually on. The pressure difference between the top and the bottom of the column is below 1 mbar. Separation results:

component Composition (weight- ' Main run trailing leader II 3.42 2.05 - III 83.62 1.30 0.25 IV 1.52 93.24 18.85 Vl 10.90 3.27 75.33 VI 0.19 0.14 5.57 Other 0.35 3.46 0.73 Quantities [kg] 2.29

The 3.46 kg of VI obtained with a melting point of 90 ° C. correspond to a rectification yield of 88%. Of the The residue is 86 g (132% by weight). Pre-run and post-run can be treated as in Example 1.

Example 3

6.04 kg of a mixture produced by chain chlorination of 3.83 kg of m-xylene was obtained, with the following composition:

«-Chlor-m-xylene (VIII)
«A-dichloro-m-xylene (XIl)
«A'-dichloro-m-xylene (IX)
α, α, α'-trichloro-m-xylene (X)
Other components

17.05% by weight

9.86 wt%

53.56% by weight

14.20% by weight

533% by weight

are subjected to the rectification process as described in Example 1. Head pressure: 15 mbar. Gas loading: 231 kg / h. Return ratio 10: 1. The head temperature rises from 80 to 141 ⁰ C and the temperature of the bubble contents from 138 to 163 ° C gradually. The pressure difference between the head and the bladder is below 1 mbar. Separation results:

Component Composition [% by weight]

Flow main run overrun

VIII 54.81 - - XII 28.34 0.06 - IX 8.73 96.28 22.03 65 X - 2.65 76.01 Other 8.12 1.01 1.96 Quantities [kg] 1.87 2.88 1.12

Il

The obtained 2.88 kg of IX from the melting point 34 ° C corresponds to a rectification of 85.6%. The residue 65 g (1.08% by weight). Forward and After-run results, separately or together exhaustively with chlorine under the conditions of the side chain ~> Tenchlorination treated, 5.36 kg aA, rt.a ', «', a'-hexachloro-m-xylene (XV) a purity of 97.8% according to gas chromatographic analysis.

Example 4 _[(|

6.48 kg of a mixture that by side-chain chlorination of 2.62 kg of p-xylene was obtained, with the following composition:

Λ, Λ, Λ'-trichloro-p-xylene (XVIIl) 12.94% by weight '■

«,«, «.« '- Tetrachloro-p-xylene (XlX) 4.94% by weight

Λ, ΛΑ ', α'-tetrachloro-p-xylene (XXI) 50.04% by weight

«,« AA'A'-pentachloro-p-xylene (XXII) 25.97% by weight

Λ, Λ, Λ, α ', α', α'-hexachloro-p-xylene

(XXlII) 5.55% by weight

Other components 0.56% by weight

are subjected to rectification as described in Example 1. Head pressure: 8 mbar. Gas loading 2.26 kg / h. Return ratio: 10: 1. The head temperature increases from 129 to 151 "C and the temperature of the bubble contents from 147 to 164 ¹ C gradually. Separation results:

component Composition [Ciew.- ¹ ' llaupüau! A. trailing leader 1.56 0.51 XVlIl 70.32 2.26 0.57 XIX 21.52 92.52 15.80 XXI 8.12 3.26 67.03 XXII - 0.Ί4 Ί4.9; -! XXIlI - 0.26 1.11 Other 0.04 3.01 2.3 (> Quantities [kg [ 1.09

The 3.01 kg of XXI obtained with a melting point of 93-95 ° C. correspond to a rectification yield of 86%. Residue: 102 g (1:58 wt ⁰ ''). After side chlorination with chlorine, the first and last run results in 3.59kg Λ, Λ,'.ΛΆ'-Hcxachlor-p-xylene (XXII!) With a purity of 99.63% according to gas chromatographic analysis.

Example 5

4.57 kg of a mixture by side chain chlorination of 3.60 kg of p-chlorotoluene was obtained with of the following composition:

p-chlorotoluene

p-chlorobenzyl chloride (XXX)
p-chlorobenzal chloride (XXXI)
Other components

14.01 wt%

6835% by weight

15.17 wt%

2.47% by weight

are subjected to rectification as described in Example 1. Head pressure: 30 mbar. Gas oil load: 135 kg / h. Reflux ratio 10: 1. The top temperature rises from 58 to 126'C and the temperature d s bubble content from 124 to 14O ⁰ C during the Rektifizierens to?.

The pressure difference between head and base is below 1 mbar.

component Composition (CJeu.- - Main run '•1 trailing Vorlaul " - 1.75 p-chlorotoluene 98.32 0.66 95.32 2.81 XXX !, 68 2.53 87.37 XXXI 0.40 9.82 Other 2.98 0.81 Quantities [kg]

The 2.98 kg of XXX melting point of 29 ⁰ C correspond to a Rektifikationsausbeute of 91%. Residue: 82 g (1.81% by weight) of the insert. There are no signs of decomposition. Lead and trailing results, separately or together, by exhaustive chlorination of the side chains, 2.01 kg of p-chlorobenzotrichloride (XXXII) with a purity of 9.4% according to gasuiiuiViäiügraphischcr analysis.

Example 6

4.36 kg of a mixture produced by side chain chlorination of 2.71 kg of o-chlorotoluene was obtained with of the following composition

o-chlorotoluene 0.88% by weight

o-chlorobenzyl chloride (XXlV) 20.42% by weight

o-chlorobenzal chloride (XXV) 67.93% by weight

o-chlorobenzotrichloride (XXVl) 8.90 wt. %

Other components 1.87 wt%

are subjected to rectification as described in Example 1. Head pressure: 30 mbar. Gas loading: 1.98 kg / h. Return ratio: 10: 1. The head temperature rises from 102 to 139 ° C. the temperature of the contents of the bubble from 131 to 152 "C during rectification ¹ x; in

The pressure difference between the head and the bladder is below 1 mbar.

component composition (weight ⁰ »]

Pre-run main run after-run

o-chlorotoluene
XMV

XWl

Λ nc! ero

Quantities [kg]

3.34

86.71

8.22

1.73
1.02

0.80

97.28

1.72

0.20

2.78

18.21 74.22

7.57

0.48

The 2.78 kg of XXV with a melting point of <30X correspond to a rectification yield of 9.550. Residue 53 g (1.22% by weight). There are no signs of decomposition. Result in pre-carriage and post-carriage, separately or together by exhaustive chlorination of the side chains 1.86 kg of o-chlorobenzotrichioride (XXVI) a purity of 96.2% according to the gas chromatograph Analysis.

Example 7

418 kg of a mixture obtained by chlorinating 247 kg of p-xylene with the following composition

Λ-α / .orp-xyiol (XVl)
xA-dichloro-p-xylene (XX)
Λ, Λ'-dichloro-p-xylene (XVII)
«AA'-tricblor-p-xylene (XVIIl)
«AAA'-tetrachloro-p-xylene (XIX)
αΑΑΆ'-Tetrachloro-p-xylene (XXI) Other components

7.45 wt.%

8.72% by weight

52.21% by weight

25.85 wt. - ^{1 vol}

0.75 equiv-0 / o

3.50% by weight

1.52% by weight

are separated in a heatable rectifying column, which essentially corresponds to that of Example 1, but has a diameter of 70 mm and a separation length of 2.30 m and is completely filled with the cylindrical ceramic separating elements B 16 cm in height. The column is equipped for continuous operation with an inlet halfway up. To obtain component XVII as a pure substance, it is rectified three times as follows. The first pass with a head pressure of 18 mbar and a reflux ratio of 2.5: 1, the second pass with a head pressure of 10 mbar and a reflux ratio of J.3: 1, the third pass with a head pressure of 10 mbar without Return executed. The gas loading is 5.4 kg / h in all passes. The distillates of the passages are collected separately. The head temperatures are 93, 130 and 136 ⁰ C, the temperatures of the evaporator contents 143, 155 and 151 ° C in the order of the passages. The pressure difference between head and evaporator is around 1 mbar. Separation results:

Component Composition of the distillate

[% By weight of 1

Passage

1 2 3

Other

Quantities [kg]

41.83

48.76

9.24

0.17
65.8

0.07 0.26 98.57 0.53 0.07 0.08 0.42

211.3

2.23 83.56

2.09 10.16

1.96

138.0

ΛΑΑ.Λ ', Λ'-pentachloro-p-xylene

(XXII) 25.97 wt. O / o
ΛΑΑΑΆΆ'-hexachloro-p-xylene

(XXIII) 5.55% by weight
Other components 0.56Ge \ v.- ° / o

are subjected to electilication as described in Example 7 in order to obtain component XXI as a pure substance. The first pass is carried out at a head pressure of 10 mbar and a reflux ^ratio of 13: 1, the second pass at a head pressure of 8 mbar and a reflux ratio of 9: 1, the third pass without reflux at a head pressure of 8 mbar. The gas loading is 5.4 kg / h in all passes. The head temperatures are, in the order of the passes, 143, 144 and 150 ⁰ C, the temperatures of the evaporator contents 161, 163 and 168 ° C. The pressure difference between head and evaporator is around 1 mbar. Separation results:

Component Composition of the distillate

[% By weight]

Passage

1 2 3

XVIII

XIX

XXII

XXIII

Other

Quantities [kg]

40

The 211.3 kg of XVII of melting point 100-101 ⁰ C correspond to a Rektifikationsausbeute of 95.4%. The residue is 2.6 kg (0.62% by weight). Decomposed signs of tongue do not occur. First and last run, treated separately or together exhaustively with chlorine under the conditions of the side chain chlorination, α, θΑΑΆΆ'-hexachloro-p-xylene of a purity of 99.42%, or in the case of partial chlorination, mixtures corresponding to the starting materials of Examples 4 and 8, which after gas chromatographic analysis deliver one or more desired pure substances through renewed rectification.

Example 8

328 kg of a mixture obtained by chlorinating 132 kg of p-xylene with the composition

ÄAA'-trichloro-p-xylene (XVIII) 12 ^ 4% by weight

a / xAA'-tetrachloro-p-xylo! (XIX) 434% by weight «AA'A'-tetrachloro-p-xyiol (XXI) 50.04% by weight

63.07

22.80

12.87

1.17

0.09
62.8

0.41

1.08

96.23

2.14

0.14
151.6

7.74
74.68
15.85

1.73

111.3

The 151.6 kg of XXI with a melting point of 94-96 ° C correspond to a yield of 89%. Residue 1.93 kg (0.59% by weight) of the insert. Lead and lag result, separately or together with Treated chlorine under the conditions of side chain chlorination, (ΧΑΑΑΆΆ'-hexachloro-p-xylene (XXIIl) a purity of 99.13% according to gas chromatographic analysis.

Example 9

65 Following the procedure of Example 1, the after-runnings from Example 4 of 2.36 kg, 15.80% by weight of symmetrical tetrachloro-p-xylene (XXI), 67.03% by weight of pentachloro-pxylene (XXII) and 14.98 wt. O / o hexachloro-p-xylo! (XXIII) as main components used again as starting material and separated by rectification into first, main and final.

1.60 kg XXII of a purity of 99.6% are used as the main run and 035 kg XXIII as a tail run 973% purity obtained.

The first runnings contain over 90% XXI and can be subjected to a rectification again or by renewed chlorination of the side chain into products completely chlorinated in the side chain, or by Core chlorination in products completely chlorinated in the Kerr with a degree of side chain chlorination as transferred in advance.

Example 10

A chlorination mixture according to the starting material of Example 7 with main contents

of 52.2% by weight a / x'-dichloro-p-xylene (XVlI) and 25.8 .Gew.-o / o (XVIII) in addition to 7.4% by weight XVI and 8.7% by weight XX is converted into the completely chlorinated products in the core.

A rectification according to the information in Example 7 delivers a fraction in the second pass which is 98.4%
and a fraction with a low degree of side chain chlorination and a fraction with over 80% a / t / i'-trichloro-pa ^ Äe-tetrachloro-xyloI, which can be separated again or perchlorinated in the side chain.

308 129/297

Claims (1)

Patent claims: 1. Process for the distillation separation of side-chain chlorinated alkylaromatics and their core chlorinated derivatives for the purpose of making them pure, characterized by the following measures: