AU594850B2 - A method for the treatment of dinitroanilines to reduce their nitrosamine content and/or to stabilise them against the formation of nitrosamines - Google Patents

Description

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AUSTRALIA

Patents Act 5 4 (XWEi'E SPECIFICATION

(ORIGINAL)

Class Int. Class Application Number: Lodged: Complete Specification Lodged: Acceptad: Published: nlis dJocunt p. *amenmcpts Made U'W Pririt setiOn 4 9 and Is correct to r lie M'llting.I APPLICANTV'S REFEfl.'CE: E018504 BENI/PR/db Name(s) of Applicant(s),* Fj~rhimica S.p.A.

Address(es) of Applicant(s): Via Porzaflo,, IManerbio (Brescia),

*ITALY.

Address for Service is: PHILLIPS 0-RflNDE jl-,1TZPATRICK Patent and Trad~e Hark AttorneyEs 367 Collins Street Melbourne 3000 AUSTRALIA Complete Specification for the invention entitled: 1)A 1 7HD FO THE TREMUT OF DINITROANILINFS TO REDUCE THEIR NITRSAMINE CThENT ANDA)R TO! STABILISE THEM AGAINST THE FORM4ATION OF

NITROSAMINES

Our Ref 79914 POF Code: 1249/64268 The following statement is a full description of this invention, including the best method of performing it known to applicant(s):, 6003q/ 1-1 1 A- I The present invention relates to a method for the treatment of nitroan'lines to reduce their nitrosamine content and/or to stabilise them against the formation of nitrosamines.

The method relates in particular to the treatment of 2, 6-dinitro-N, N-di-n-propyl-4-trifluoromethyl aniline, known under the trade name of trifluralin a compound which is widely used in agriculture as a herbicide.

ii** The presence of a nitrosamine content greater than !ppm in dinitroaniline compositions used as herbicides is considered undesirable due to the confirmed S".a carcinogenic properties of nitrosamines in animals.

0* The methods described in the technical literature for the removal of nitrosamines from crude trifluralin obtained by the synthesis method, include the treatment of the trifluralin with a concentrated aqueous solution of hydrochloric acid, or with hydrogen chloride gas (US patent No. 4,226,789) or with chlorides of inorganic acids (US patent No. 4 ,1 8 5 ,0 3 5 or with chlorine or bromine (US Patent No. 4,127,610).

It has, however, been found that even after these treatments, the di-n-propyl nitrosamine content increases during prolonged storage of the treated technical trifluralin and during subsequent industrial fusion and formulation operations for the preparation of herbicidal compositions. In particular, the increase in the nitrosamine content is encouraged by the presence of iron and is thus inevitable when trifluralin is stored in iron containers, even if they are lacquered.

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505 _i 2 Tests carried out by the Applicant have shown a progressive increase with time in the nitrosamine content of samples of technical trifluralin stored in glass containers and in glass and iron containers, subjected to heating to a temperature of 95 0

C.

A further confirmation of the problem of the reformation of nitrosamines following heating of purified trifluralin is provided by the comparative examples in European patent application No. EP-A-126591 which relates to a method for the stabilisation of dinitroaniline compositions by the incorporation in the dinitroaniline of an addition compound of a bisulphite of ammonia or of an alkali metal and an aldehyde or a ketone.

US Patent No. 4,537,992 describes a method for the removal of the nitrosamines by subjection of the dinitroanilines to a treatment with acyl chlorides and aminobenzoates.

This method does not, however, provide any guarantee with regard to the stabilisation of the treated dinitroanilines against the reformation of nitrosamines.

German patent application No. DE-OS-333 45 157 describes a method for the production of dinitroanilines substantially free from nitrosamines and their stabilisation against the formation of nitrosamines.

The method provides for the treatment of the dinitroanilines with aromatic or aliphatic sulphonic acids, with chlorosulphonic acid or with amidosulphonic S S

S

S

3 acid.

Amongst the compounds indicated, only dodecylbenzene sulphonic acid is used commercially, this, however, being used exclusively for the stabilisation of dinitroanilines which have previously been purified of nitrosamines. In fact, since this compound is a surfactant, its presence in the higher concentration required for the purification of crude nitroaniline may give rise to the undesired formation of foams and emulsions when water is present, even in small S* quantities, in the reactor used for the treatment.

The object of the present invention is to provide a method which constitutes an overall solution both to the problem of the removal of aLtrosamines from crude trifluralin and to the problem of stabilising the purified trifluralin against the formation of nitrosamines.

For this purpose, the subject of the present invention is a method for the treatment of dinitroanilines having herbicidal action to reduce their nitrosamine content and/or to stabilise them against the formation of nitrosamines, characterised in that it comprises the steps of adding to the dinitroanilines an effective C quantity of an aliphatic or aromatic sulphonic acid having the general formula 0

NX

i i- i

J

I i mR 4 in which X is a halogen and s selected from the group consisting of linear o~ branched aliphatic radicals having from 1 to 10 carbon atoms, cycloaliphatic C5-C 6 radicals, aryl radicals and aryl radicals substituted with lower (C 1

-C

3 alkyl groups.

Although the method is generally effective as regards the stabilisation and/or purification of dinitroanilines having herbicidal action, particular reference will be made to tri. -alin in the following *fee eo** part of the present descriptic' 9 In the method according to the invention, typically 4h4.

abhov-mentioned sulphonyl chloride is added to the trifluralin in the fused state, in quantities of from 0.01 to 1% by weight with respect to the weight of the trifluralin The stabilisation is typically carried out at a temperature higher than the melting point of the trifluralin and generally within the range 70 to 100 0 C. The sulphonyl chloride is preferably added, in this case, in a ratio of from 0.01 to 0.1% by weight with agitation and the agitation is continued for a period of between 1 and 4 hours. In the case of the purification treatment carried out on crude trifluralin the treatment is effected at a temperature of between 95 and 110 C, the sulphonyl chloride being added in a ratio preferably of from 0.3 to 1% by weight. The agitation is continued fo a period of between 8 and 10 hours.

The treatment according to the invention is effective even when precursor compounds for nitrosamines, such as, di-n-propylamines, for example, are present in the trifluralin subjected to treatment.

The results obtained by means of the method acccording to the invention will be illustrated by the following examples of experimental tests.

Example 1 (Reference example) The following example illustrates the phenomenon of the formation of nitrosamines in purified trifluralin satisfying the requirements established by the EPA, that is, having a nitrosamine content of less than 0.5ppm following heating in glass containers and in the presence of glass and iron.

120g of trifluralin having a nitrosamine content

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(NO-DIPA below) of less than 0.5ppm, obtained by means of a purification treatment carried out in the laboratory with hydrochloric acid, were placed in a glass container into which a 1Qcm 2 test piece of sheet iron was introduced. The container was then kept at a temperature of 95 C for a period of from 12 to 150 hours. A parallel control test was carried out with the use of the same quantity of trifluralin without the sheet iron test piece.

0* 0 Table I below indicates the nitrosamine contents aftir 100 and 150 hours under the above conditions, the analyses being effected with a thermal energy analyser

(TEA).

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7 6 TABLE I

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S 9 S0 S. I 5*

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NO-DIPA NO-DIPA NO-DIPA CONTAINER content after content after content after hours 100 hours 150 hours (ppm) (ppm) (ppm) GLASS 0.65 1.04 1.2 IRON The results in Table I confirm that the purification treatment with aqueous hydrochloric acid is not effective in stabilising the triflural2,n and that the increase in the nitrosamine content is greater when ir-on is present in the container.

Example 2 various series of technical trifluralin samples were prepared containing known quantities of di-n-propyl nitrosamine (NO-DIPA) Some of the sar--".es prepared3 also contained a known quantity of di-n-propylamine,

(DIPA).

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4 The compositions of the prepared samples subjected to treatment are shown in Table II below.

TABLE II 0 so 00 NO-DIPA DIPA SERIES content content (ppm) (ppm) A 0.24 B 1.93 C D 0.24 2 E 0.24 F 1.97 2 G 1.97 H 2.51 1 9.2 0 of technical trifluralin were placed in a glass container into which a 10 cm 2 teat piece of sheet iron was introduced and to ,which a known quantity of -a A3iph a tic or .,romatic acid selected from the above-mentioned group was added. The 8 container was tien kept at a temperature of 95 C for a period of from 12 to 160 hours.

A parallel control test was carried out for each sample, with the use of the same quantity of trifluralin but without the addition of the treatment additive. Samples were taken after 12, 48, 96, 150 and 160 hours and, in each case, their NO-DIPA contents were determined by TEA.

The results of the tests are shown in the following tables, see** e s S go *l -Llr lL .L i i iL41 i 4> Ii .uji

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ge S E Rl I ES A lquantity of NO-DIPA (ppm) at various; t im-±s AD D IT IV E 12 h 4,9h196h 1-50 h MMIRN SULPiVIINL 0.1 0.05 0.05 0 05 A s.

QULOPJDE

OCTNNIE SI)LPUGKYL 0.1 0.05 0.05 0.05 Abs.

BENZENE SLJLPHGNYL 0.1 0,05 0,05 0 05 Abs., Cl LRID)E COW MNL 0.87 1,41 1.231 1.,41 2~ *00 0 0 00 00 S ER IES 13 quantity of NO-DIPA (ppm) at various tijhu-s ADD IT IV J% 12h 148_hJ 96h __150 1 ME~TIAI\1E SULPIMYT, 0.1 0,05 0.05 0,05 Abs.

OCrANF StILPIIONY\YT., 0.1 0.17 0.05 0.05 Abs.

CHLORIDE

BEI1ZENE St)LPUONYL 0.1 1.61. 0. 33 0,05 Abs.

ILORIDr CohN\rFo1. 2,6 2.56 2.8 2,53 S E H~ .1 E S C qluantity of NO-E)IPA (PPM) at variwxs t iiin--s A D D IT I VE 12 h 148 r 96 h 150I MEINANE SULPUONYL 0.1 Q.38 0.05 00 0Cf[LORIDE OCAN ULHNYJ0.1 0,05 0.05 0,05 B3ENZENE SULI:?110NYL 0,1 0,7 0.05 0,05 CO~'TUL 43,84 4.87 5.52 S E R I E S D quantity of NO-DIPA (PPM) at various timas A DD IT I V F 12 h 48 h 196h 10 lSh EIANE SUTLIIONYL 0.1 0.06 0.05 0.05 TUMI.4 .SULIIQNYL, 0,107 0, 05 (I I w RI D P 4

I

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0000 0 o 0060 *0 a0 00 a I *0 go

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*i S i S 9* 00 0 06 S *i *i S E R I ES E quantity of NO-DIPA (ppm) at various tiiies A D D IT I V E 12 h 48 h 96 h 150 h L17IANEL SULPHOYIIO 0.1 0.07 0.05 0,05 Q ILOIDE BENDZFIE SULPHONTYL 0.1 0.83 0.05 0.05

CIILORIDF

CONTRL 1.3j 1.82 2.91 S E R I ES F quantity of PO-DIPA (ppm) at varims tb.Cs ADD IT I VE J 12 h 48 h 96 hI 2O OGPPNF SULPHONYL 0.1 0,74 f0.44 pI'LJEN SUPHONL 0.1 0.2i33 0.05 0 .05 i

UTLORIDE

cOtrlNL 2.76 2,$6 3.71{ S E R I qu G latity Of NO-UIPA (pm) at various tims A D DITI V %5 12 h 48 h 96h 1_50 h, t'ANE SULLIJONYL 0,1 0.05 0.05 0,05 QCl RIDE p.'TQWE*N SnVINYL 041 2.17 2.1 1,43 2,54 3i81 4,15 :I I e.g.

0 000000 0 6 *0*006 0 0* 60 0

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SERIE S H QUANTITY OF 140-DIPA AT VARIOUS TIM S ADDITIVE 12h 48h 96h 160h 'ETHMAF "-ULPIIONYI, C.1WPJRDE 0.02 2.2 1.68 1.37 0,4 BI-NZFN, SUJLPIIONYL, GIOID 0.02 1.56 0,64 0,24 0,15 CONTFCL 2.4 2.57 2.85 2,52 QUANPTY OF NO-DIPA SERIES I AT VA1RIMXS TINIFS ADDITIV E 1% 121h 46h 95h IGQh

K

1 It!Ni S-bTpONy't, ~HQI~ Q.02 5.72 0, 29 0,24 0.22 10o66 11 85 12,0Z 10,68 777 000i g i 0 *«0 .4

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0@ 13 The experimental tests reported in the tables clearly indicate, not only the stabilisation of the nitrosamine content, but above all a progressive reduction thereof with time, even after prolonged heat treatment. The effectiveness of the sulphochlorides according to the invention in the stabilisation and reduction occurs both with parified trifuralin thac is having a nitrosamine content which satisfies the EPA standards, and with technical trifluralin having a nitrosamine content greater than 0.5ppm. The sulphochlorides according to the invention are, furthermore, effective when added in concentrations of only 0.02% by weight with respect to the trifluralin and even when di-n-propylamine (DxL)A) which, as is known, is thought to be a precursor of nitrosamines, is present in the trifluralin It follows, therefore, that the additives according to the invention are able to display their action both at the stage of commercial formulation of herbicidal compositions including trifluralin and in the treatment of technical trifluralin obtained by synthesis.

Example 3 Destruction of ni.rosodipropyla'" ine in trifluralin with chlorides of sulpho' ic acids.

crude On the basiF of the positive results obtained in the stabilisation tests, the possibility of using chlorides of sulphonic acids as nitrosamine destroyers was also checked. For this purpose, a series of tests was carried out with the use of samples of trifluralin having NO-DIPA contents in the range 60 tp 350ppm and aulphonic acid chlorides in quantities of between 0.3 and 1% with respect to the crude trifluralin at I I I JL L 14 temperatures of between 95 and 110 C, for periods of 8-10 hours.

Te-t i.

500g of crude trifluralin having an initial NO-DIPA content of 119ppm, were introduced into a 1 litre flask provided with an agitator, and to this were added 2.5g of methane sulphonylchloride, equal to by weight of the crude trifluralin The mixture was *se heated to 95 C for 8 hours with rapid agitation. A sample was then taken and analysed by TEA and a NO-DEPA content of 0.07ppm was found.

o The following table summarises the conditions and results of the tests carried out.

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INITIAL FINAL 1%to TEIPERATURR 'r'IME NO-DIPA NO-DIPA 2 trifluraline .Io) (IlOURS) (ppm) (ppln) 350 ABSENT BSCi 1 95 8 20 350 ABSENT MSC1 1 95 8 30 110 0.06 MSC1 1 95 8 40 110 0.25 0501 1 95 8 50 350 ABSENT riSCi 0.5 95 8 G 0 119 0.07 SC1 0.5 95 8 60 0,15 MSC1 0.5 95 8 60 0,3 BSC1 0.5 105 8 90 101 0.18 NSC1i 0.5 100 100 le5 0.35 OSC1 0.5 100 110 125 0.15 OSCI 0,5 95 120 110 0.31 BSC1 0.3 105 130 60 0.28 OSCi 0.3 110 140 350 0,22 MsC1 0,3 150 138 0118 MSC1 0,3 95 8 S U

S.

a 5506 q *0 I BSC1 0SC1 scl BENZENE StPIHOMTfRIDE OCrANE 'SULPHIOQ ILORIDE MpmI lN SULPI OCULO1DE 16 In all the tests carried out, the t-erm "absent" relates to the NO-DIPA content and should be understood to mean that the nitrosamine content was less than the lower threshold liimit of the TEA instrument.

In all the tests carried out the final NO-DIPA content, after treatmient for 8-10 hours, was less than the limit of 0.5ppm required by the standards.

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Claims (6)

1. A method for the treatment of dinitroanilines to reduce their nitrosamine content and/or to stabilise them against the formation of nitrosamines, comprising the steps of adding to the dinitroaniline compositions a quantity of an halide of an aliphatic or aromatic sulphonic acid of between 0.01 and 1% by weight of the dinitroaniline to the dinitroaniline in the fused state with agitation, said halide of an aliphatic or aromatic sulphonic acid having the Jo general formula: off* 0S 0e *00 0 *5 S S a 0S 99*99: 0 as S 0e S S0* S* 0 i X S R II where X is a halogen and R is selected from the group consisting of aliphatic radicals having from 1 to 10 carbon atoms, cycloaliphatic C 5 -C 6 radicals, aryl radicals and aryl radicals substituted with CI-C 3 alkyl groups.

2. A method according to Claim 1 for the stabilisation of technical-quality dinitroanilines against the formation of nitrosamines, in which the halide of a sulphonic acid is added to the technical dinitroaniline in quantities of from 0.01 to 0.1% by weight with respect to the dinitroaniline.

3. A method according to Claim 1 for the destruction of nitrosamines in crude dinitroaniline, in which the halide of a sulphonic acid is added to the crude dinitroaniline at a temperature of from 95 to 110 0 C, in quantities of from 0.3 to 1% by weight with respect to the dinitroaniline.

4. A method according to any one of Claims 1 to 3, in which the halide of a sulphonic acid is selected from the group consisting of methane sulphonyl chloride, ethane sulphonyl chloride, octane sulphonyl chloride, benzene sulphonyl chloride, and toluene sulphonyl chloride.

A method according to any one of Claims 1 to 4 in which the dinitroaniline is trifluralin. i 18

6. A method according to Claim 1 substantially as hereinbefore described with reference to Examples 2 and 3. DATED: 14 November, 1989 FINCHIMICA S.p.A. By their Patent Attornaeys: PHILLIPS ORMONDE FITZPATRICK 0 00 0*e 0 0 0