DE1539807A1 - New oxdiazole derivatives and the use of oxazole derivatives as scintillator substances - Google Patents

Description

New application documents required for the Druok of the Disclosure Carift - File number. P 15 33 8C7.9

CIBA AKTIMGESELLSCHAfT, BASEL (SWITZERLAND)

Case 5775 / E
Germany

New Oxdiazole Derivatives and Use of Oxazole Derivatives as scintillator substances

The present invention relates to new oxazole derivatives as well the use of selected oxdiazole derivatives for scintillation counting processes in the event of atomic decay events.

There are probably already a number of oxdiazole derivatives for the purposes of scintillation counting, especially in liquid Systems have been proposed, however, these connections do not have all of the simultaneous

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be able to meet the requirements to be placed on them to a sufficient extent. This mainly relates to a high one Energy transfer with an extremely short decay time and at the same time a low absorption coefficient for self-emission and at the same time high solubility in the solvents preferred for liquid scintillation measurement methods or solvent systems. Sufficient chemical stability (exposure to light, acid and alkali resistance) is also to be assumed anyway.

It has now been found that a small selection of certain oxdiazole derivatives meet all of these requirements Fulfills. According to the invention, this involves the use of oxdiazole derivatives with the structural element

wherein A represents an alkyl group containing 3 to 7 carbon atoms and having at least one chain branch and m and η stands for the integer 1 or 2 and η means that A, is present once or twice as a substituent, as scintillator substances.

The focus of the invention is on the use of oxdiazole derivatives of the formula

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where A is an alkyl group containing 3 to 7 carbon atoms and having at least one chain branch and B. is a hydrogen atom, a phenyl group, an optionally branched alkyl group containing 1 to 7 carbon atoms or a lower alkoxy group and m is an integer from 1 to 2 , as a scintillation substance for liquid scintillation counting.

• The appropriate scintillation fluids are characterized in that they use benzene or an alkylbenzene liquid at room temperature as the solvent or a dioxane-naphthalene-water mixture and 0.01 to 5 percent by weight, based on the total amount of the scintillation liquid, an oxdlazole derivative of the formula (2).

In the context of the above definition, the use of oxdiazole derivatives is of preferred importance formula

9 0 9 3 5 1/0 f; i 9

where Bp is a tert. Represents butyl group or a phenyl group, in liquid scintillation counting methods. In this case, the scintillation liquids preferably contain Toluene as solvent and 0.01 to 5 percent by weight, based on the total amount of the scintillation liquid, an oxdiazole derivative of the formula (3).

The following compounds from the abovementioned classes of oxdiazoles may be mentioned as examples:

(4) h, c-c - <=> - σ σ-σ

N N

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From the above it can be seen that the use of the mentioned scintillator substances of particular importance for liquid scintillation counting methods in Connection with certain solvent systems. The invention thus also includes a method for Counting of atomic decay events, which are accompanied by emission of ß-radiation, using the liquid scintillation method in predominantly aromatic hydrocarbons as a scintillator solvent, which thereby is characterized that as a scintillation fluid Solution of an oxdiazole of the formula

wherein A-, B, and m have the meaning given above, in Benzene, an alkylbenzene liquid at room temperature, a methanol-toluene, methylcellosolve, naphthalene-toluene or a dioxane-naphthalene-water mixture is used.

The liquid scintillation counting method described above The specific oxdiazoles mentioned are scintillators on their own

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that meet all of the above requirements. she can also appear as so-called "primary solutes" in the narrower sense, i.e. as primarily through high-energy radiation of an atomic act of decay for light emission excited substance can be used, which with usual "secondary solutes ", i.e. substances with long-wave emission are combined. Such suitable" secondary solutes "are, for example 1,4-di- [2- (5-phenyloxazolyl)] benzene, 1,4-di- [2- (4-methyl-5-phenyloxazolyl)] benzene and 1,4-di (4'-isopropylstyryl) benzenes. Furthermore there is the possibility of combination with neutron capture solutes, 7-rays converting substances, gels, suspension aids or given solubilizers. It goes without saying that there are both internal and external counting methods practicable.

Suitable solvents for the liquid scintillation counting method are mainly aromatic, liquid at room temperature (if no solvent combinations are used) Hydrocarbons such as benzene, toluene, xylenes, ethylbenzene, 1,3. »5-triethylbenzene, cumene, Cymene, phenylcyclohexane, and ethers such as anisole, dioxane, 1,2-dimethoxyethane, non-aromatic hydrocarbons such as Cyclohexane, heptane, etc., or finally mixed solvents such as toluene / methanol and optionally water, toluene / ethanol, naphthalene / dioxane, naphthalene / toluene and optionally water, naphthalene / dioxane / water, methylcello- * ("gamma conversion solutes") j other solvent additives,

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solve / naphthalene / toluene and optionally water, naphthalene / tributyl phosphate or other commercially available aromatic hydrocarbon mixtures recommended for this purpose.

The concentration of the oxdiazole derivatives to be used according to the process can in principle vary within wide limits and is determined or limited on the basis of practical requirements. For example, the lower limit must be such that adequate transmission to the scintillation recording system (photomultiplier) is guaranteed, while the upper limit is set by the noticeable absorption of self-emission ("self-quenching"). Although, for example, for the production of stock solutions (which are accordingly diluted for use), concentrations of 10 $ and higher are easily possible, the practically interesting working concentrations are between about 0.1 and 3 $, preferably 0.4 to 2%. (always percentages by weight based on the total weight of the solution).

In addition to toluene, preferred solvent systems are the systems toluene / methanol (1: 1) with the addition of about 2% water, methyl cellosolve / toluene / naphthalene (4O: 60: 8) with up to 4 # water, dioxane / toluene / naphthalene (40: 60: 8) with up to 10% water, or toluene / methanol / ethanolamine (50: 44: 6). The arrangement of the solvent system depends primarily on the nature of the substrate to be measured or the isotope to be measured, whereby for the latter, for example

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l4 Ί

^{C, H, S 35} , P ³² , Pe ⁵⁹ , Fe ⁵⁵ , J ¹²⁵ and J ¹ ^ ¹ may be mentioned as the most frequently considered representatives.

The technical progressiveness of the inventive, According to the oxdiazoles to be used, there is in particular the fact that they can be used on their own (that is, without "secondary solutes") Represent scintillators that not only meet all other requirements to a high degree, but above all have excellent solubility properties, as they are in the case of the previously known The highest quality scintillators from the Oxdiazole series were missing. This mainly relates to particularly good solubility in transparent solvents with a high flash point.

In addition to the field of application described above, the oxdiazoles defined above can generally can be used where the transformation of high-energy radiation into measurable light is a task is.

An essential area of application concerns, for example, the use for so-called plastic scintillators. One can here the scintillator in the polymeric substance in question (polymer, polycondensate or polyadduct) before the final deformation operation (casting, drawing, pressing, injection molding, etc.) distribute homogeneously and then deform. Otherwise there is also the possibility of using the scintillator as the starting materials for the production of the Polymers, for example the monomers before the polymer

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sation, adding and then polymerizing out (examples: Polystyrene, polyvinyltoluene). Further variants in the application of the above-mentioned scintillators result readily from the usual fields of work of this technology.

The oxdiazoles to be used for the present process can be prepared by methods known per se be like for example.

a) by reacting 2 moles of a carboxylic acid

OOH or their esters.

with 1 mole of hydrazine in the presence of a phosphoric acid, which is less watery than orthophosphoric acid (especially polyphosphoric acid) - a particularly symmetrical one Oxdiazole, i.e. A, = B ,, suitable method, or

b) by treating diacylhydrazines of the formula

\ J JL 1

(for m - 1 according to formula [2]) with non-sulfonating, dehydrating agents, or

c) by the action of imido ethers on the corresponding carboxylic acid hydrazides at elevated temperatures in the presence a solvent.

The parts and percentages given in the following manufacturing instructions and examples are as far as they are nothing else is noted as meaning parts by weight or percentages by weight.

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A. To 400 parts of polyphosphoric acid, 83Ji ϊ> ⁰ 5 'are zugetropt at 50 ° C with stirring, 10.0 parts of hydrazine hydrate keeping the temperature at about 80th C increases. Thereupon 71.2 parts of p-tert. Butylbenzoic acid entered and the temperature increased to 125 ° C within 30 minutes with the exclusion of air. The mixture is stirred for 8 hours at 125 to 130 ^° C., a clear, colorless solution being formed. After cooling to about 50 ° C., 1000 parts of cold water are poured into 1000 parts with thorough stirring, and the reaction product which has separated out is suction filtered and washed with water until neutral to the Congo. After drying, 66.7 parts (corresponding to 100% of theory) of 2,5-bis [4'-p-tert-butylphenyl (I ')] - 1,3 * 4-oxdiazole of the formula are obtained

³ I II

-N CH ₅

as a nearly colorless powder, melting at 135 ° C to I36 C ^0. After recrystallization from ethanol-water (7s1), colorless flakes with a melting point of 39 to 14 ° C. are obtained.

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B. 29j 6 parts of the diacylhydrazine of the formula

(12) - _N.

NH HN

are brought to the boil in 150 parts by volume of freshly distilled thionyl chloride with stirring in one hour and refluxed for a further 2 hours, with one clear, pale yellow solution results. The excess thionyl chloride is then first under normal pressure and then im Distilled off under vacuum. The residue is triturated with ice water, whereupon it solidifies. It is filtered and washed with water neutral and dries. About 2J, 6 parts, corresponding to 99.3 # of theory, 2- [4'-tert. Butylphenyl- (1 ')] -5-phenyl-1,3,4-oxdiazole of formula (6) as a colorless powder, which after recrystallization from ethanol-water (3 * 1) gives colorless leaves. It melts at 98 to 99 ° C and, when dissolved in ethanol, shows 3 absorption maxima:

X = 288 m [i (6 = 30400) max. ^ ^V

238 πιμ {£ = 7550) 232 πιμ (£ = 7350).

Solubility in 100 ml of ethanol at 20 ° C: 4.00 g.

According to the above rule, the following 1,3,4-oxdiazole derivatives are produced:

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a) 2- [4'-tert. Butylphenyl- (l ')] - 5- [4 "-methylphenyl-

(l ")] - 1,3,4-oxdiazole of the formula

ι:

N N

Colorless, fine crystals from ethanol-water (7ί2): Melting point: 111 to 112 ° C;

Solubility in 100 ml of ethanol at 20 ° Cj 2.92 g; UV absorption in ethanol:

5ΐμ (£ = 31000)

Max

242 ηιμ {t = 8650).

b) 2- [4'-tert. Butylphenyl- (1 ')] - 5- [4 "-methoxyphenyl- (1")] - 1,3,4-oxdiazole the formula

* 3

N N

Colorless, fine crystals of ethanol; Melting point: 162.5 to 163.5 ° C.

Solubility in 100 ml of ethanol at 20 ° C: 0.605 gj UV absorption in ethanol:

) i _max = 298 ΐημ (£ = 32300)

249 ^ μ (£ = 6100).

c) 2,5-bis [4'-tert. Butylphenyl- (1 ') 3-1.3 * 4-oxdlazole of formula (5) [see above].

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C; 212 g of diphenyl-4-carboxylic acid hydrazide are in 2000 ml of dry o-dichlorobenzene were stirred at room temperature. After the addition of 197 g of 4-tert. Butylbenzoyl chloride and 81 ml of anhydrous pyridine is the thick paste inside one hour heated to 100 to 105 ° C and at this Stirred temperature for one hour. The reaction mixture then increases to 140 to 145.degree. C. in a further hour heated, whereby you get almost a solution. Within 45 minutes, 90 ml of thionyl chloride are then added at 140 to 150 ° G the reaction mixture was added dropwise, giving a cloudy solution which, after the end of the dropwise addition, for 15 minutes is subsequently stirred.

The majority of the solvent is now evaporated by applying a vacuum. Then 1000 ml of ethyl alcohol added dropwise so that the contents of the flask are always at reflux temperature, which soon becomes a crystalline Precipitation receives. It is suction filtered at room temperature, the residue is washed with alcohol and dried. You get 295 g gray-tinged, crystalline powder with a melting point of 135 to 136 ° C.

Crystallization from n-propanol with the addition of activated charcoal gives 240 g of the compound of the formula

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as colorless prisms from melting point I36 to 137 ⁰ C. -C ₂₄ H ₂₂ ON ₂ (354.43)

Calculated: C 81.32 H 6.26 N 7.90 found: C 81.27 h '6.14 N 7.92.

D. 5.2 g of oxalic acid dihydrazide and 10 ml of anhydrous pyridine are added to a solution of 14.5 g of 4-isopropylbenzoyl chloride in 200 ml of anhydrous ο-dichlorobenzene at 40 to 50 ° C. In the course of 2 hours, the reaction mixture is then heated to 130 to 135 ° C., a thin paste being obtained. ⁰ C over 30 minutes 20 ml of thionyl chloride are then added dropwise at from 130 to I35, to obtain a clear solution. The mixture is stirred for a further 15 minutes at this temperature and then allowed to cool.

Excess thionyl chloride and the solvent are then almost completely evaporated under vacuum. It is then stirred with 100 ml of methanol, whereby one light brown crystalline precipitate is obtained, which is suction filtered and washed with methanol, Twice crystallization from alcohol with the addition of fuller's earth yields 7 g of the bis-oxdiazolyl compound formula

H "C _{Λ 0}

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as colorless needles with a melting point of 175 to 176 ° C. (37 ^, 45)

Calculated: C 70.57 H 5.92 N 14.96 Found: C 70.65 H 5.91 N 14.84.

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In the following examples, all measurements were made in low-potassium counting jars with a Liquid scintillation spectrometer "TRI-CARB" Mod. Ex-2 from Packard Inst. Comp., Inc., Illinois.

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-.17 -

example 1

20 ml of a solution of 5 g of the compound of

Formula (9) and formula (5) in 1 liter of toluene are converted into a

14th

Counting vials and 1 ml of a solution of C - labeled benzoic acid with an activity of 0.01 micro-Curie offset. The counting glass is placed in the counter and the number of pulses per minute (counts per minute = opm) is determined. Are found at a high voltage of 900 volts and one Setting from 100 to 600: 13630 cpm for connection (9) and 132OO for compound (5).

Example 2

20 ml of a solution of 5 g of the compound according to formula (9) or formula (5) in 1 liter of toluene are in a Counting glasses given. To this, 0.1 ml of H -labeled toluene with an activity of 0.01 micro-Curie is added. At a High voltage of 1100 volts and a setting of 100 to 600 are 6600 with connection (9) and with connection (5) Measured 5930 cpm.

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Example 3

20 ml of a solution of 10 g of the compound of formula (9) or formula (5) in 1 liter of toluene are in a counter vial with 1.0 ml of a solution of S ^ -labeled l-Butyl-3- (p-tolylsulfonyl) urea in ethyl alcohol offset. The activity added was 0.01 micro-Curie. The counter jar is then placed in the counter and the pulses per minute are measured. With a high voltage of 900 V * lt and a setting from 100 to 600 in the measuring channel found 13200 cpm for compound (9) and 12950 cpm when using compound (5).

Example 4

20 ml of a solution of 10 g of the compound of formula (9) in a mixture of 400 methyl cellosolve, 80 g Naphthalene and 600 ml of toluene are placed in a measuring glass. To do this, 0.5 ml of H -labelled water is mixed with a Activity of 0.01 micro-curie added. At a high voltage from 1200 volts and a setting from 100 to 2200 pulses per minute are measured.

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Example 5

1 g of 2- [4'-tert. Butylphenyl (1 ')] -5-biphenylyl-1,3,4-oxdiazole of formula (9) together with 100 g of vinyltoluene (o-, m- and p-isomer mixture) into a Pyrex glass tube that is fused on one side (Diameter of 25 mm) given. The tube is repeatedly evacuated to 0.1 mm Hg pressure and with pure Purged with nitrogen. Finally, it is again evacuated to 0.1 mm Hg and the tube is melted shut. The pipe is within Heated for 2 hours in an oven at 110 ° C and carefully turned to ensure that the compound has the formula (9) goes completely into solution. The temperature is then set to polymerize the contents for 24 hours at this level, 24 hours at 130 ° C and 48 hours Maintained 140 ° C. The subsequent cooling down and relaxation phase at 75 ° C extends over 8l hours. After cooling to room temperature, the resulting transparent polymer core detached by smashing the glass tube. For measuring the relative pulse height this is turned to a diameter of 20 mm, sawn into 10 mm thick disks and polished. as The relative amplitude (RPH) is a measure of the light yield

1 ^ 7
of the pulses generated by Cs ^J% conversion electrons.

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Measurements are made with a Philips 56 AVP photomultiplier with a POPOP / TP ratio (i.e. 2,2-p-phenylene bis (5-phenyloxazole) / terphenyl ratio) of 1.30 (photo multiplier characteristics) . The commercially available plastic scintillator NE 102 A (Nuclear Enterprises Ltd.), whose RPH value is set equal to 1.00, is used as the measurement standard. The plastic scintillator according to the invention shows an RPH value of 1.10. A plastic scintillator made in the same way from polyvinyltoluene, which contains 2% of the compound of the formula (9) and ^{0.1 # 2- [4 i} -biphenylyl (l ^l ) J-6-phenyl-beiizoxazole, gives the high RPH Value of 1.23.

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Claims (2)

Claims 1. Use of oxdiazole derivatives with the structural element wherein A, one containing 3 to 7 carbon atoms and at least represents an alkyl group having a chain branch and m and η represents the integer 1 or 2 and η means that A, is present once or twice as a substituent, as a scintillator substance. 2. Use of oxdiazole derivatives of the formula r O / \ -G C- Il N "N wherein A. one containing 3 to 7 carbon atoms and at least represents a branched chain alkyl group and B-, a hydrogen atom, a phenyl group, a Containing 1 to 7 carbon atoms, optionally branched Represents an alkyl group or a lower alkoxy group and m represents an integer of 1 to 2 as a scintillator substance for liquid soltillation counting. 909851/0929 Neua U "! 'Er! Cigon (Ar :. -3.-Jos Alterunaaget.v.43.i" Use of oxdiazole derivatives of the formula wherein B- a tert. Represents butyl group or a phenyl group, as a scintillation substance for liquid scintillation counting. Use of oxdiazole derivatives of the formula as a scintillation substance for liquid scintillation counting. 909851/09 2 9 5 JtJ 8 U / The compound of the formula HCC Ο-C ^{σ 3} I RH N S The compound of the formula The connection taiag of the formula 0 / χ ca, ι 3 £ C- € 0-OhHS, «Ill 1 3 m - »η — ir 9 09 851/0929