DE1234701B - Process for the preparation of isotopic aromatic hydrocarbons by catalytic cyclization of isotopic acetylenically unsaturated hydrocarbons - Google Patents

Description

Process for the production of isotope-containing aromatic hydrocarbons by catalytic cyclization of isotope-containing acetylenically unsaturated Hydrocarbons There are already numerous processes known which lead to the formation of isotopes of carbon or organic compounds containing hydrogen, z. B. hydrocarbons lead. So you get z. B. to containing deuterium aromatic hydrocarbons in such a way that one is a mixture of the concerned Hydrocarbons and deuterium conducts via a nickel contact, being a part of the hydrogen present in the aromatic hydrocarbons versus deuterium is exchanged. This method leads to incompletely deuterated ones aromatic hydrocarbons. This well-known exchange process has the Disadvantage that a separation of the not or only to a small extent deuterated Connections from the more highly deuterated end products is very difficult. At paying ponds Uses of the deuterated hydrocarbons, e.g. B. in reactor technology, however, is the presence of a proportion of hydrogen containing compounds or the presence of only partially deuterated compounds is often significant Disadvantage. The known exchange method also has the disadvantage that a certain Part of the deuterium used as the starting material through the formation of deuterium containing organic by-products bound and the actual intended use is withdrawn. Furthermore, it is known by cyclization of isotopes containing Acetylene by the Reppe process under pressure and elevated temperature in the presence from nickel carbonyls to labeled aromatics. However, it does form By-products that are difficult to separate, and in particular an undesirable one Isotope exchange with the auxiliary products, so that the desired products are special Separation procedures must be subjected.

From French patent 1 232 343 it is known isotope-free To cyclize acetylene compounds to benzene derivatives in the presence of catalysts, by the action of organometallic compounds of metals from I. to III. Group of the periodic table on compounds of transition elements of the IV. To VIII. Groups are obtained. In British Patent 802 510 describes a process in which benzene derivatives are prepared from acetylene compounds are in the presence of catalysts caused by the action of titanium tetrachloride on organometallic compounds of non-transition metals from I. to III. group of the periodic table. German patent specification 1,135,436 discloses a process for the cyclization of acetylene derivatives in the presence of Aluminum- or titanium catalysts. The three patents give no indication of the application the method for isotope-containing compounds.

In the Journal of the Chemical Society [London], 1935, pp. 851 bis 855, after all, is a purely scientific production method for hexadeuterobenzene described. Tellurium oxide is used as a catalyst at a reaction temperature of approx 650 "C. The yields are small. In contrast, according to the invention Method containing isotopes in a simple manner and under simple conditions aromatic hydrocarbons in remarkably good yields.

The present invention relates to a method of production of aromatic hydrocarbons containing isotopes by catalytic cyclization of isotope-containing acetylenically unsaturated hydrocarbons or mixtures such hydrocarbons at negative pressure, atmospheric pressure or slightly overpressure; it is characterized in that one has the loading of the exclusive action of halides and / or Oxyhalides of the metals niobium and tantalum or tungsten or addition compounds of these halides with alkali or alkaline earth halides or subjected to POCl3 at -30 to 250 ° C.

The products produced according to the invention contain the isotopes of the hydrogen atom, namely deuterium [D; lH] or tritium [T; lH], and / or that Carbon isotope with the mass number 14 [l4; C] in the following possible combinations: 1. Hydrogen and 14C 2. Deuterium and 12 6C 3. Tritium and BC 4. Deuterium and 14 6C 5. Tritium and 164C Aromatic hydrocarbons can thus be produced which contain either deuterium, tritium or 16C isotope or deuterium and 14C isotope or tritium and 14C isotope.

Examples of aromatic hydrocarbons containing isotopes of carbon and / or hydrogen which can be prepared by the process according to the invention are the hydrocarbons of the general formula (I): where C * denotes the 12C atom or the 164C atom, R1, R2, R3, R4, R5 and R6 each denote hydrogen, deuterium, tritium or a saturated or unsaturated hydrocarbon radical optionally containing isotopes, n denotes an integer of 1 to 4 and where at least one of the symbols C must represent a 146C atom or at least one of the symbols R1 to R6 deuterium or tritium or an isotope-containing hydrocarbon radical.

As starting materials for the compounds of the general formula (1) come z. B. Compounds of the general formula R7 - C * # C * - R8 (II) in question, wherein C * has the meaning given above, R7 and R8 have the same meaning as The above symbols R1 to R6 and at least one of the symbols C * have a 16C atom or at least one of the symbols, and R8 deuterium or tritium or an isotope-containing one must mean saturated or unsaturated hydrocarbon radical.

The inventive method is thus suitable, for. B. for production of unsubstituted or substituted, for example trisubstituted, Benzols containing isotopes, which are substituted by alkyl groups, alkenyl groups, Contain aryl groups or cycloalkyl groups, the atoms of the substituents can be wholly or partially replaced by the corresponding isotopes.

Examples of compounds of the general formula (11) may be named: acetylene-ds, D - C # C - D; Methylacetylene-d, CH3 - C C -Methyl-d3-acetylene, CD-C C -methyl-d3-acetylene-d4, CD3-C CD; Acetylene-1,2-146C, H'46C 1111 14bC -Acetylene-1,2-14 6C-d2, D-164C 1111-C -Vinyl-d3-acetylene-d4, CD2 = CD - C 1111 CD or divinylacetylene-1,2,3,4,5,6-14 6C, 14 6CH2 = 14 6CH - 14 6C # 14 6C - 14 6CH = 14 6CH2.

Furthermore, it is possible according to the new method, isotopes containing, partially substituted, e.g. B. to produce singly and disubstituted benzenes, by using a mixture of acetylene or isotopes containing acetylene and acetylene derivatives, z. B.

Acetylene derivatives containing CH3-C = -C-H or isotopes, e.g. B.

CH3-C C-D used as starting material.

In a particularly advantageous manner, that according to the invention is suitable Process for the production of isotopes of carbon and / or hydrogen containing benzene from isotopes of carbon and / or hydrogen Acetylene, surprisingly good yields being achieved.

The use of NbCl5, NbOCl8, NbBr5, NbF5, TaCl5, TaBr5, TaF5, WCl6, or WOCl4 as cyclization catalysts in the production of isotopes the aromatic hydrocarbons containing carbon and / or hydrogen leads to a surprisingly good result. As useful addition compounds are the double salts of the halides or oxyhalides of niobium and tantalum with alkali or alkaline earth halides, namely sodium, potassium and barium chloride, or the addition compounds with phosphorus chlorides or

To mention phosphorus oxychlorides. The halides preferably used or oxyhalides of niobium, tantalum or tungsten are not sensitive to oxygen, non-flammable and can be regenerated after the reaction has ended.

In the production of aromatic, with the '4C isotope "marked" Hydrocarbons by the process according to the invention can be, for. B. also from Correspondingly "marked" acetylene emanate, as one would by the action of water respectively.

D2O receives on Bal4C2. This gives DC 1111 CD, H'46.C = - '4, CH or D14C14CD. As is well known, the term “marked connections” is understood to mean also compounds in which only a certain proportion of the molecules contain isotopes, however, the radiation activity of the isotope-containing portion is sufficient to to be able to prove and trace the connection as such.

The method according to the invention can be carried out in various ways Way. So z. B. carried out the cyclization reaction in the gas phase are, the catalyst is used in solid form, advantageously in one heatable reaction tube, and a constant one containing the starting material Gas flow over the catalyst is directed. The catalyst can can also be applied to a porous support, optionally with a Activation of the catalyst support system, e.g. B. by heating at a suitable Temperature before use in the reaction is appropriate.

The catalyst itself or the catalyst-carrier system can still inert filling compounds, such as. B. pumice stones or asbestos contain.

By deforming in the usual way, e.g. B. in an extruder, by Granulating or pilling can also be the particle size of the catalyst mass are awarded whichever is most favorable for the particular reaction apparatus used is. The moisture in the air is expediently kept away from the reaction apparatus, for example by having a dried gas stream or N2 before the start of the reaction passes through and the gases entering during the reaction in the usual way dries.

The temperature inside the reaction chamber can be the above embodiment of the method within relatively wide limits vary.

It has proven to be useful in the case of the production of the deuterated Benzene according to the above embodiment of the present invention has a temperature range between 80 and 2500 C and in particular between 100 and 200 "C proved.

It is also possible to produce the desired end product, e.g. B. Deuterium containing benzene, to be isolated from the gas stream leaving the reaction chamber, z. B. by condensation at a suitable low temperature or by absorption, and the proportions of unused starting gas that may still be present in the gas stream, z. B. deuterated acetylene, fed again to the catalyst in a cycle. However, one can also proceed in such a way that the gas stream is released after it has left the reaction space and passing through a cold trap in a gasometer and that in the gasometer gas that has entered, which may still contain unused starting material, later fed back into the reaction chamber from the gasometer. Appropriately one brings on both Connect a gasometer to the end of the apparatus, so that you can turn it around at will the direction of the gas flow, the reaction up to the complete conversion of the starting material can continue.

In accordance with the preferred embodiment of the present invention the catalyst to be used, if necessary with the exclusion of atmospheric moisture, suspended in an inert and expediently anhydrous organic solvent and introduced into the suspension, a gas stream, which in the reaction as Contains starting material serving compound. The beginning of the reaction will be there recognized that the gas introduced is absorbed by the suspension to a significant extent will.

The suspension is optionally before or during the introduction brought the gas stream to the desired temperature.

One can also proceed in such a way that one contains the catalyst Freeze the solvent in a high vacuum by cooling and in a second vessel, which is connected to the first by a tap, the labeled acetylene hydrocarbon frozen separately by cooling. A connection is established by opening the tap to the first vessel, removing the coolants. The low boiling one Acetylene hydrocarbon thereby gets into the solvent, whereby the cyclization occurs.

Aliphatic, cycloaliphatic or aromatic solvents can be used as solvents Hydrocarbons are used, for example benzene, m-xylene, higher-boiling Mixtures of aliphatic hydrocarbons, cyclohexane or methylcyclohexane. It is particularly expedient to choose a solvent whose boiling point is lower differs from the boiling point of the end product to be obtained so much that solvent and final products can be separated from each other by distillation.

This is the case, for example, in the case of production according to the invention of deuterated benzene possible, with the choice of a suitable solvent, the one has a correspondingly higher boiling point than deuterated benzene, and when used a temperature inside the suspension which is between the boiling point of the deuterated Benzene and the higher boiling point of the solvent that formed deuterated Distilling benzene continuously from the reaction vessel and by condensation or to isolate adsorption. In the case of the manufacture of deuterium containing Compounds are mainly hydrogen-free solvents, e.g. ethylene tetrachloride, proven.

As a rule, from 2 to 40 g, preferably used, per liter of solvent 10 to 30 g of cyclization catalyst.

In the production of 1ß4C labeled benzene can be used for the purpose of more suitable Determination of the radiation intensity normal benzene used as solvent will. This takes place on the basis of the method features that characterize the invention no exchange of 14C for 12C takes place, so that the cyclization Benzene is labeled according to the 16C content of the acetylene used.

The temperatures in the reaction vessel can be between -30 and y2500 C. So, for example, in the case of production according to the invention from deuterated benzene from deuterated acetylene these temperatures are very useful proven; particularly good results are achieved at temperatures between -10 and 2000 C. The rate of introduction of the gas stream is expediently chosen so that most of the starting material is taken up by the solution; one can however, proceed in such a way that the portion of the starting material emerging as unused gas is repeatedly returned to the catalyst suspension in a cycle. The amount of converted acetylenically unsaturated hydrocarbon, based on the amount of catalyst present depends on the starting material and the reaction conditions away. As a rule, between 0.5 and 70 g of acetylenically unsaturated hydrocarbons are used implemented per gram of catalyst.

If the method according to the invention is based on radiation-active isotopes containing acetylenically unsaturated hydrocarbons, one is special use well-sealed apparatus.

According to the invention, the cyclization reaction is carried out under reduced pressure, atmospheric pressure or a slight overpressure, d. H. at about 100 to 1000 mm Hg column. That If desired, the process can also be carried out at a pressure of 1000 to 2000 mm Hg column take place.

The acetylenically unsaturated compounds subjected to cyclization can be in gaseous or react in liquid form. In the latter case, they become in the inert solvent containing the catalyst added dropwise in portions or continuously.

Another preferred embodiment of the method according to the invention also consists in using the catalyst in the presence of a mixture, the (a) at least one saturated aliphatic hydrocarbon or one alicyclic hydrocarbon and (b) one from the final product by distillation separable unsaturated aliphatic or unsaturated alicyclic hydrocarbon, z. B. contains a diene. This embodiment is particularly useful when as Catalyst a compound of tantalum or niobium, TaCl5 or NbCl5, uses will. The advantageous effect is shown above all in a shortening the time between the introduction of the starting material, e.g. B. of the isotopes containing Acetylene, lies in the solvent and the start of the reaction that leads to formation of the desired end product, e.g. B. to benzene containing isotopes leads. at At a moderately elevated temperature, the reaction usually occurs immediately with the Introduce the starting material.

Furthermore, in the advantageous embodiment mentioned, a almost complete absorption of the isotope-containing acetylene in the solvent possible and a particularly good yield of the desired end product can be achieved. Under the compounds of component (b), which in such a way to activate the catalysts, especially the tantalum compounds, are mainly the dienes, in particular butadiene and isoprene to highlight. The compounds of the above Component (b) are surprisingly effective as activators even in small amounts. In general it is not necessary to use the activators of component (b) during to add to the whole duration of the reaction; rather, it is sufficient in most cases an initial addition of these compounds to start the reaction. The activation of the catalysts, e.g. B. the tantalum compounds, with the help of the compounds the component (b) can be used as a solvent by simply admixing the latter to the Serving compounds of component (a) take place. However, one can also proceed in this way that the compounds of component (b) are added to the gas stream, which is the starting material, z. B. the isotope-containing acetylene contains, before entering the actual Admixing reaction space, e.g. B. by an injector. It is also possible the catalyst, e.g. B. the tantalum halide or niobium halide, prior to its distribution in the solvent, e.g. B. the compounds of component (a), by treatment with to activate a relatively small amount of a compound of component (b).

The compounds to be prepared according to the invention can, for. Am known way used for analytical purposes and technological investigations will. Those hydrocarbons which contain deuterium can be known due to their molecular weights differing from those of the hydrogen-containing compounds z. B. with the help of the mass spectrograph, while those hydrocarbons which contain 'BC or tritium, in a known manner due to their radiation activity can be tracked and proven. Furthermore, those to be produced according to the invention can be used Connecting applications are used with particular advantage in reactor technology, z. B. as a coolant, reflectors or moderators.

As is well known, the term »moderators« refers to those connections which slow down the so-called "fast neutrons" and convert them to "slow" resp. )) thermal neutrons «are able to convert.

For the purposes mentioned above are those to be made in accordance with the invention Compounds particularly suitable whose hydrogen atoms largely or practically are completely replaced by hydrogen isotopes, e.g. B. highly deuterated benzene.

The compounds prepared according to the invention stand out by a surprisingly high resistance to the effects of heat and Radiation of all kinds as well as through high neutron braking effect and low neutron absorption the end.

Also for other technical applications that are not in the field the reactor technology, the isotopes of the invention turn out to be hydrogen containing compounds mainly due to their resistance to Heat and radiation and their good heat exchange capacity are generally considered to be very suitable, z. B. as a coolant in units that work under extreme conditions. Isotope-containing aromatics which contain polymerizable double bonds, for example the divinyl model, trivinylbenzene, which is available from labeled vinyl acetylene be converted into polymeric compounds by known processes. You can do that Manufacture highly deuterated plastics.

The invention is described in more detail in the following examples. The temperatures are given in degrees Celsius: mC means millicuries and mM Millimoles.

The radioactivity measurements were carried out with 14C-acetylene with a Ionization chamber in connection with a vibration capacitor measuring amplifier, for all other samples with a liquid scintillation counter.

Example 1 In a three-necked round bottom flask with a capacity of 21, 400 g calcium carbide placed in an absolutely dry nitrogen atmosphere. With help of a 200 ml of deuterium oxide were then slowly added dropwise to the dropping funnel, with complete Deuterated acetylene was formed, which after passing through a cold trap in a dry gasometer was collected. At the end of the acetylene evolution, with little nitrogen, the reaction product is flushed as completely as possible into the gasometer.

To convert the deruted acetylene to benzene, a 500 ml four-necked flask used containing 200 ml of anhydrous ethylene tetrachloride and in it slurried contained 5 g of NbCl5. A vibromixer was inserted through the main connector, which ensured that the liquid was vigorously mixed. The second nozzle served for the introduction of the thermometer, the third connection for the introduction of the acetylene. The fourth port connected the flask to a second, empty one via a cold trap Gasometer, but was usually closed by a tap during operation.

At 40 "C the connection of the reaction flask to the acetylene container opened and by briefly opening the outlet to the empty gasometer the nitrogen displaced by acetylene. Immediately strong acetylene absorption set in with a dark color the A catalyst slurry, with an absorption of about 400 ml / min. was maintained. The temperature was thereby reduced by cooling adjusted to 15 to 50 "C. When the absorption decreased noticeably, the output became to empty gasometer reopened for about 30 seconds, reducing accumulated Nitrogen was removed and the absorbance returned to its original value.

After the reaction had ended, the reaction solution was filtered and discharged pure, completely deuterated benzene from the filtrate by fractional distillation won.

Yield: fully deuterated pure benzene: 95 g = 680 / o of theory. analysis benzene Found 1 Calculated F calculated O /, C 85.6 1 85.7 92.3 O / o D (H). - 14.25 14.3 7.7 molecular weight .... 84.1 78.1 In addition to the pure deuterated benzene, fractions containing the deuterated benzene in enriched form were also obtained. These are advantageously presented as solvents in the following reactions.

The catalyst residue (30 g), which in addition to carbon also contains deuterium contained, was incinerated and the resulting heavy water recuperated.

When performing the above reaction using 5 g of TaBr5 as a catalyst and from 500 ml of a commercially available mixture of aliphatic Hydrocarbons from Shell Chemical Corp., bp 180 to 200 "C, as solvents and a similar result is achieved at a temperature of 83 "C. Here, an immediate onset of the reaction at 80 "C can be achieved by the acetylene gas stream entering the reaction chamber a small amount of isoprene admixed, expediently by injecting the isoprene into the connection between Gasometer and reaction flask with the help of a hypodermic needle. It changes color the suspension immediately yellow and then black, the incoming deuterated Acetylene is at an inflow rate of 600 ml / min. completely absorbed by the solvent and almost completely converted into deuterated benzene.

Corresponding results were obtained when using WCl; or WOCl4 as catalysts and a mixture of 400 ccm methylcyclohexane and 100 ccm of n-xylene as a solvent.

Example 2 2 g of NbCl5 were placed in an Al2O3 boat under nitrogen placed in a refractory glass tube and heated to 100 ° C there. At this Temperature was completely deuterated acetylene from a dry gas container taken and, after passing through a cold trap, in an inflow amount of about 3 1 H. allowed to enter the reaction space.

Upon contact with the NbCl5 in the reaction tube, the NbCl5 changed color dark with strong heat emission. The temperature in the reaction space rose from even at 1200C. After about half an hour there was a slight drop the temperature noticeable, after which it was slowly heated to 200 "C.

That formed when the D C C - D came into contact with the darkly discolored NbCl5 Deuterated benzene was converted into one by the excess unconsumed D - C C - D connected cold trap rinsed, frozen there and the unused D-CC-D caught in the gasometer connected to the cold trap. After emptying the The first gasometer to continue the reaction was the direction of the gas flow vice versa and the benzene now in the one at the original inlet end of the reaction tube attached cold trap.

In this way 16 g of practically completely deuterated benzene, C6D6 contaminated with traces of DCl was obtained.

Carrying out the reaction described above at temperatures of 10 °, 50 ° and 1300C similarly led to the formation of benzene.

Also that amount of heavy water which is used in the development of the deuterated acetylene from calcium carbide had been bound as Ca (OD) 2 for the most part by calcining what is in the acetylene evolution vessel Residue can be recovered. With careful implementation of the measures for Recovery of the portion of deuterium not converted in the first reaction and reuse in the following reaction batches is possible more than Introduce 90% of the deuterium present in the starting material (D2O) into the benzene.

Example 3 An apparatus analogous to that in the example was used 1 described. 13 g TaCl5 and 0.4 g NbCl5 were placed in the 1000 ml reaction flask in 350 ml of the mixture of aliphatic hydrocarbons used in Example 1, Boiling point 180 to 200 "C, placed under nitrogen and cooled to -100C. At At this temperature the nitrogen was displaced by dry, deuterated acetylene and the connection to the acetylene gasometer kept open. After 8 minutes of intense With stirring, the white slurry slowly turned yellow, then light green-olive green and finally blue. At the same time, an increasing absorption of acetylene began finally, for reasons of apparatus, to 1.21 / min. was restricted. The temperature rose fairly quickly to 10 ° C, where it was cooled with a cold bath of -10 "C could be held. A total of around 1701 deuterated acetylene were converted, first for around 90 minutes at a speed of 1.21 / min., whereupon the Recording speed gradually slowed down. By distilling out were 150 g of fully deuterated benzene (80 ovo of theory) and 24 g of a black, Ta, Cl, C and D containing residue isolated.

The analysis of the benzene gave: D20 = 0.9482 ° C./085.77 n200 1.4986 D ° / o 14.58 mass spectrum: 95.9 0 / o C6D6 4.00 / 0 C6DsH 0.1 0 / o C6D4H2 degree of deuteration: 99.3 0 / o.

Example 4 The apparatus used for the cyclization reaction of consists of two flask-shaped glass vessels A and B, which are connected through a glass tube are connected. The vessels are under a tap system and with the connecting pipe connected or detachable. Both glass vessels can be placed in coolant, for example in liquid air or liquid nitrogen, and the whole system is connected to a high vacuum pump.

2.0 g of anhydrous benzene and 10 mg of niobium pentachloride are placed in vessel A entered, whereupon the vessel is immersed in liquid nitrogen and high vacuum is created. The solid state of aggregation is achieved through cooling.

14C-acetylene is obtained by the decomposition of C-barium carbide, which in turn is accessible by pyrolysis of 14C-barium carbonate with barium, with water. The 16C-acetylene formed is purified over potassium hydroxide and Phosphorus pentoxide in vessel B, cooled with liquid nitrogen, under high vacuum condensed. Vessel B contains 52 mg 4jC acetylene (4.48 mC).

The connection from vessel A to B is used to initiate the reaction opened and the coolant removed from vessel B. The labeled acetylene condenses into vessel A in 10 to 30 seconds.

After this time, the coolant is removed from vessel A. When defrosting The beginning of the cyclization reaction is evident in the reaction mixture by gradual Blue discoloration. After shaking vessel A for 2 hours at room temperature, the The vacuum is released, the reaction mixture is filtered off and the clear benzene solution distilled. The radiochemical yield, measured by the specific Activity of 16C-benzene: 0.151 mC / mM, from which a stoichiometric one is calculated Yield of 3.94 mC = 87.9% of theory.

For the verification of the chemical and radiochemical identity of the '6C-benzene obtained is a batch of the' 4-benzene in bromobenzene and one of them Sample converted to benzoic acid. The obtained values of the specific activities are: benzene 0.151 mC / mM, bromobenzene 0.148 mC / mM and benzoic acid 0.152 mC / mM. This provides evidence of the chemical and radiochemical purity of the obtained 164C benzene.

Example 5 The same apparatus as in Example 4 is described used. 10 mg of niobium pentachloride are placed in vessel A with 2.0 g of “Shellsol T” and converted into the solid state by freezing out in a high vacuum. Afterward 52 mg of the 14C acetylene (4.48 mC) described in Example 4 are removed from the vessel B condensed into vessel A. After thawing the reaction mixture is 2 hours shaken, after aerating added 2.0 g of benzene, filtered off and fractionated by Distillation separated the benzene.

The radiochemical yield, measured by the specific Activity of 14C benzene: 0.137 mC / mM, from which a stoichiometric one is calculated Yield of 3.51 mC = 78.3% of theory.

Example 6 The same apparatus as in Example 4 is described used. 10 mg mixed crystals of 970 / o tantalum and 30 / o niobium pentachloride are used brought into vessel A with 2.0 g of absolute benzene and freeze out in a high vacuum transferred to the solid state. Then 52 mg of that described in Example 4 are added l, tC acetylene (4.48 mC) condensed from vessel B into vessel A. After thawing the reaction mixture is shaken for 2 hours and, after aeration, filtered off and the clear benzene solution is distilled.

The radiochemical yield, measured by the specific Activity of '4C-benzene: 0.146 mC / mM, from which a stoichiometric one is calculated Yield of 3.74 mC 8394% theory.

Example 7 By reacting barium carbide with tritium water, Tritium acetylene produced. The same apparatus as in Example 4 is described used. 12 mg of niobium pentachloride are added to the vessel with 2.0 g of absolute benzene A and converted into the solid state by freezing out in a high vacuum. Then 52 mg of tritium acetylene (7.43 mC) are transferred from vessel B into the vessel A condenses. After thawing the reaction mixture, it is shaken for 2 hours Aeration filtered off and the clear benzene solution distilled.

The radiochemical yield, measured on the specific Activity of tritium benzene: 0.245 mC / mM, from which a stoichiometric one is calculated Yield of 6.28 mC - 84.6% theory.

Claims (3)

Claims: 1. Process for the production of isotopes containing aromatic hydrocarbons by catalytic cyclization of isotopes acetylenically unsaturated hydrocarbons or mixtures of such hydrocarbons at negative pressure, atmospheric pressure or slightly overpressure, characterized that the loading of the exclusive action of halides and / or Oxyhalides of the metals niobium, tantalum or tungsten or Addition compounds of these halides with alkali or alkaline earth halides or subjected to POCls at -30 to 250 "C. 2. The method according to claim 1, characterized in that as Cyclization catalyst NbCl5, NbOCl3, NbF5, NbBr5, TaCl5, TaBrs, TaF5, WCl8 or WOCl4 or a mixture of two or more of these compounds is used. 3. The method according to claim 1 and 2, characterized in that one the cyclization reaction in the gas phase or preferably in an inert, preferably carries out solvent separable from the end product by distillation. Documents considered: British Patent No. 802 510; French Patent No. 1,232,343; Journal of the Chemical Society (London), 1935, pp. 851 to 855. Older patents considered: German Patent No. 1 135 436.