IE47127B1 - Purification of dinitroanilines by removal of nitrosamine impurities - Google Patents
Purification of dinitroanilines by removal of nitrosamine impuritiesInfo
- Publication number
- IE47127B1 IE47127B1 IE1430/78A IE143078A IE47127B1 IE 47127 B1 IE47127 B1 IE 47127B1 IE 1430/78 A IE1430/78 A IE 1430/78A IE 143078 A IE143078 A IE 143078A IE 47127 B1 IE47127 B1 IE 47127B1
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- nitrosamine
- trifluralin
- ppm
- hcl
- concentration
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- C—CHEMISTRY; METALLURGY
- C07—ORGANIC CHEMISTRY
- C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
- C07C209/00—Preparation of compounds containing amino groups bound to a carbon skeleton
- C07C209/82—Purification; Separation; Stabilisation; Use of additives
- C07C209/84—Purification
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- C—CHEMISTRY; METALLURGY
- C07—ORGANIC CHEMISTRY
- C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
- C07C211/00—Compounds containing amino groups bound to a carbon skeleton
- C07C211/43—Compounds containing amino groups bound to a carbon skeleton having amino groups bound to carbon atoms of six-membered aromatic rings of the carbon skeleton
- C07C211/44—Compounds containing amino groups bound to a carbon skeleton having amino groups bound to carbon atoms of six-membered aromatic rings of the carbon skeleton having amino groups bound to only one six-membered aromatic ring
- C07C211/52—Compounds containing amino groups bound to a carbon skeleton having amino groups bound to carbon atoms of six-membered aromatic rings of the carbon skeleton having amino groups bound to only one six-membered aromatic ring the carbon skeleton being further substituted by halogen atoms or by nitro or nitroso groups
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- Organic Chemistry (AREA)
- Organic Low-Molecular-Weight Compounds And Preparation Thereof (AREA)
- Agricultural Chemicals And Associated Chemicals (AREA)
Abstract
Hydrochloric acid in either 20-38% concentration or gaseous form is effective is removing nitrosamines from a number of dinitroaniline herbicides.
Description
The present invention is directed to a process for the removal of nitrosamines from dinitroanilines, by the use of hydrochloric acid or gaseous HCl.
The dinitroaniline class of compounds includes numerous commercial herbicides. Recently a new analytical device, known as a thermal energy analyzer (TEA), has been developed (J. Chroroatogr. 107 (1975), 351 and references there cited; and N-Nitroso Compounds in the Environment, IARC Scientific Publication #9 (International Agency for Research on Cancer, Lyon, 1974), p. 40). The TEA analyzes specifically for the nitroso (-NO) group, and is capable of detecting the nitroso group at concentrations as low as 0.02 ppm - much lower than prior analytical techniques. Analysis of various dinitroanilines by the TEA reveals that some of the dinitroanilines contain very small amounts of nitrosamines. The presence of even a very small amount of nitrosamine is viewed as undesirable, because certain of the nitrosamines have been shown to be carcinogenic in animals.
The present invention provides a method for removing nitrosamines from dinitroanilines.
The chemistry of aliphatic N-nitrosamines is reviewed in Russian Chem. Rev. 40 (1) 34-50 (1971) (Eng.). The reaction of nitrosamines with inorganic acids (page 41 et seq.) is covered. The reaction of hydrochloric acid and gaseous HCl with nitrosamines is discussed.
Chem. Listy 51 937-945 (1957) reports on the kinetics and mechanism of the conversion of nitrosamines to the corresponding simple amines by strong mineral acids.
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Lieb. Ann. 345 277-288 (1906) teaches the preparation of di-n-propylamine by treatment of nitrosodin-propylamine with gaseous HCl.
None of these references teaches the use of HCl to remove nitrosamines from the particular dinitroanilines of the present invention. Moreover, it is unexpected that this removal would be achieved so efficiently by the use of HCl.
The amount of nitrosamines present in dinitroamines can be significantly reduced with this invention.
This invention provides a process which comprises (1) contacting a nitrosamine-containing dinitroaniline selected from trifluralin, isopropalin, benefin, ethalfluralin, butralin, tendimethalin, fluchloralin, profluralin, dinitramine,
4-trifluoromethyl-2,6-dinitro-3chloro-N,N-diethylaniline,
4-methyl-2,6-dinitro-N,N-bis(2chloroethyl)aniline, oryzalin, and nitralin,
347127 (a) in liquid phase (b) with 20-38¾ hydrochloric acid or gaseous HCl until the concentration of the nitrosamine has been reduced; and (2) thereafter recovering the dinitroaniline. The present invention is directed to a process which comprises contacting a nitrosamine-containing dinitroaniline in liquid phase with aqueous hydrochloric acid or ga'seous HCl, until the concentration of the nitrosamine has been reduced; and thereafter recovering the dinitroaniline. Dihitroanilines with which the present invention can be practiced (and their
generic names where available) are (1) 4-trifluoromethyl-2,6-dinitro-N,N-di-npropylaniline (trifiuralin); (2) 4-isopropyl-2,6-dinitro-N,N-di-n-propylaniline (isopropalin); (3) 4-trifluoromethyl-2,6-dinitro-N-n-butylN-ethylaniline (benefin); (4) 4-trifluoromethyl-2,6-dinitro-N-ethylN-methallylaniline (ethalfluralin); (5) 4-tert-buty1-2,6-dinitro-N-sec-hutylaniline (butralin); (6) 3,4-dimethy1-2,6-dinitro-N-(1-ethylpropyl)aniline (tendimethalin); (7) 4-trifluoromethy1-2,6-dinitro-N-propylN-(2-chloroethyl) aniline (fluchloralin); (8) 4-trifluoromethy1-2,6-dinitro-N-propylN-(cyclopropylmethyl)aniline (profluralin); (9) 4-trifluoromethy1-2,6-dinitro-3-aminoΝ,Ν-diethylaniline (dinitraraine);
-447127 (10) 4-trifluoromethy1-2,6-dinitro-3-chloroΝ,Ν-diethylaniline (intermediate to ditramine);
(11) 4-methyl-2,6-dinitro-N,N-bis(2-chloroethyl) aniline;
(12) 4-sulfamoyl-2,6-dinitro-N,N-di-n-propylaniline (oryzalin); and (13) 4-(methylsulfonyl)-2,6-dinitro-N,N-din-propylaniline (nitralin).
Preferred dinitroanilines with which the present invention is carried out are trifluralin, isopropalin, benefin, and ethalfluralin.
Generally, the dinitroanilines are prepared by a reaction route of which the following, for trifluralin, is typical:
.-MQo NazC°3
PF, / \-PI HN°3 \ PF,_Z Hs2_ \ Z CF3 \ /*-CI “70^ — — -NO» nN(n_c3H7)a . ,·—·γΝ0ε ~y CF3-·. ,*-N(n-CsH7)i ·—»-NOs
It is believed that small amounts of nitrogen oxides remaining from the nitration step react with a portion of the amine during the amination step, generating small amounts of nitrosamine which may appear in the final dinitroaniline product. Therefore, any nitrosamine contaminant is expected to be the nitroso derivative of the alkylamine employed. However, it is conjectured that exceedingly small amounts of yet other nitrosamines may also be formed. The removal of nitrosamines, regardless of identity, is desirable, and the present process meets that objective.
The mechanism by which the present process operates is not known with certainty, but it is believed that HCl denitrosates the nitrosamine to some other species, probably the HCl salt of the corresponding amine. It is also believed
-5· ’ 47127 but not yet proven that N0C1 may be generated as part of the denitrosation. In any event, the net result is conversion of the undesirable nitrosamine to a water soluble substance which can readily be removed from the dinitroaniline.
The present process provides substantial reduction in nitrosamine concentration, regardless of the initial amount of nitrosamine. The process has been conducted with dinitroanilines containing from as little as 10 ppm of nitrosamine to as much as several thousand ppm of nitrosamine; nitrosamine concentration is generally reduced to about one-tenth of the initial amount, or less. In many cases, the nitrosamine concentration is reduced to less than about 1 ppm.
The present prooess is conducted in a liquid phase. In the instance of many of the dinitroanilines, this can be achieved by heating the nitrosamine-containing dinitroaniline to its melting temperature or higher and conducting the reaction neat. A liquid phase can also be achieved by dissolving the nitrosamine-containing dinitroaniline in a solvent. Suitable solvents include alcohols, e.g. a primary alcohol such as ethanol;' a ketone such as acetone; and hydrocarbons, both aliphatic and aromatic. Solvents comprising moieties reactive with HCl should be avoided. For example, secondary and tertiary alcohols should be avoided because of their reactivity with HCl.
The reagent to be employed in the present process is either hydrochloric acid or gaseous HCl. If hydrochloric acid is used, it should contain at least 20% HCl (by weight).
Better results have been obtained with more concentrated
-647127 hydrochloric acid, such as 33-38%. Gaseous HCl can also be employed, and this is generally a preferred mode of carrying out the present invention. In the instance of ethalfluralin, gaseous HCl has an advantage over hydrochloric acid of avoiding addition across the methallyl double bond.
The amount of hydrochloric acid or gaseous HCl to be employed is not critical, so long as the amount is effective to reduce the initial amount of nitrosamine to a lesser amount. With hydrochloric acid, 0.04 gram per 100 grams of dinitroaniline has been found satisfactory.
Similary, employing gaseous HCl, 250 ml. per 100 grams of dinitroaniline has been found satisfactory. Larger amounts (by 3X) have also worked satisfactorily but have provided no advantage. In laboratory scale reactions with gaseous HCl, addition rates of 5-90 ml./min./100 grams of dinitroaniline have been satisfactorily employed. Rates of 8-12 ml./min/lOO grams of dinitroaniline are preferred.
The reaction can be conducted at temperatures over a wide range. In general, temperatures below 140°C. are employed, and temperatures below 100°C. are preferred because of the greater risk of side reactions at higher temperatures. When conducting the process in a solvent, satisfactory temperatures vary widely with the identity of the solvent, but generally range from room temperature to 100°C. When conducting the process neat, the reaction is conducted at temperatures above the melting temperature of the particular dinitroaniline. Good results have been achieved at temperatures of fran 70 to 9O°C. especially when conducting the process neat with trifluralin (m.p., 54-5°C.), iso-747127 propalin (m.p., 30°C.), benefin (m.p., 65-6°C.), and ethalfluralin (m.p., 57-9°C.).
The reaction can be conducted at atmospheric pressures or at elevated pressures. It has been found to be advantageous to conduct the reaction with gaseous HCl at 70-90°C., and with 1-10 psig, and preferably 3-5 psig, of HCl gas pressure.
The presence of water in the nitrosamine-containing dinitroaniline has a deleterious effect on the present process. This is especially true when employing gaseous HCl in that more HCl is required for denitrosation. Therefore, when employing gaseous HCl, it is preferred that the nitrosamine-containing dinitroaniline be relatively dry, such as less than 0.2 percent of water.
The rate at which the present process proceeds will vary with the concentration of the nitrosamine, temperature, the form of HCl reagent, the rate of its addition, and other factors. The progress of nitrosamine removal can be monitored by gas chromatography or by TEA analysis. Denitrosation is generally complete in less than an hour. Time studies of the present process have shown an early drop in levels of nitrosamine, followed in some instances by a slight rise in levels of nitrosamine upon extended reaction time. It is believed that extended exposure of (1) the dinitroaniline and (2) the conjectured alkylamine denitrosation product, to the reaction conditions may result in further nitrosamine formation. Therefore, minimizing reaction times is desirable.
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Workup of the reaction mixture is carried out by conventional procedures. The workup desirably takes the form of a water wash followed by a slightly basic wash to assure removal of traces of HCl. Provision should also be made, during the course of the present denitrosation process, for the removal of by-product gases.
One preferred process comprises (1) contacting molten trifluralin with gaseous HCl at
70° to 90°C. at 2-5 psig until the concentration of the nitrosamine has been reduced; and (2) thereafter recovering the trifluoralin.
Another preferred process comprises (1) contacting molten trifluralin with 38% HCl at 70° to 90°C. until the concentration of the nitrosamine has been reduced; and;
(2) thereafter recovering the trifluralin.
The following Examples illustrate the present invention and will enable those skilled in the art to practice the invention.
Unless otherwise noted, determination of nitrosamine concentration in the following Examples was done by a gas chromatographic method sensitive down to about 0.5 ppm.
A non-detectable reading (reported below as N.D.) was considered to represent less than about 0.5 ppm of nitrosamine. A Hewlett-Packard ( Trade Mark)
Model 5711A gas chromatograph was used but the method can be carried out with any gas chromatograph apparatus equipped with a flame ionization detector. The column was a glass coil 4 ft. xl/8 inch i.d., packed with 3% Carbowax ( Trade Mark) 20M on 100/120 mesh AW DMCS
Chromosorb ( Trade Mark) G operated at 100°C.
After the nitrosamine peak eluted, the column was heated to 23O°C. and held there for about 15 minutes. The helium flow rate was 60 ml./min. A standard was employed of approximately the same concentration of the nitrosamine expected of the sample. Both standard and sample were prepared in methylene chloride.
Those Examples utilizing TEA analysis are so indicated. Analyses by this method were carried out in essentially the same procedures as described as J.
Cnraiatogr. 109(1975), 271. In the context of the. present invention
-947137 this method is considered to be sensitive to nitrosamine concentrations as low as 0.05 ppm. Where TEA analysis of the samples reported below showed no nitrosamine, it is reported as N.D.
I
In Example 2, a gas chromatography-mass spectrometry method of analysis is reported. In this method, samples were dissolved in benzene and purified by alumina column chromatography using benzene as the eluting solvent. The nitrosamine content of the sample was measured on an LKB-9000 gas chromatograph-mass spectrometer equipped with a 5%
Carbowax 20M column. The column temperature was adjusted to 130°C. which resulted in a retention time of two minutes for nitrosodi-n-propylamine. It was detected by adjusting the magnet to the molecular ion (m/e = 130) and displaying the resulting ion current on a strip chart recorder.
EXAMPLE 1: NITROSAMINE REMOVAL FROM TRIFLURALIN, 20¾
HYDROCHLORIC ACID, ETHANOL SOLVENT
Trifluralin (30 grams,, containing 256 ppm. of nitrosamine, was mixed with 20 ml. of 20% hydrochloric aci’d and 5 ml. of ethanol. The mixture was heated to 90°C. and maintained at that temperature, with stirring, for 3 hours.
The layers were separated and the organic layer washed with 10 percent sodium bicarbonate. The product was analyzed for nitrosamine? none could be detected.
EXAMPLE 2: NITROSAMINE REMOVAL FROM TRIFLURALIN, HCL GAS,
BENZENE SOLVENT
Trifluralin (10 grams of a sample containing 480 ppm. of nitrosamine) was dissolved in 200 ml. of benzene and the solution stirred and heated to reflux (80°C.). KC1 gas was passed into the refluxing solution continuously over a period of an hour. The reaction mixture was cooled slightly and washed twice, each time with an equal volume of water. The benzene layer was separated, dried over anhydrous magnesium sulfate, and filtered, and the benzene was removed on a rotary evaporator. The resulting trifluralin was analyzed for nitrosamine content by a gas chromatographymass spectrometry method. Analysis showed <1 ppm of nitrosamine.
EXAMPLE 3: NITROSAMINE REMOVAL FROM TRIFLURALIN, HCL GAS Trifluralin (50 grams) was heated to 70°C. HCl gas was bubbled through at a rate of 8-12 ml./min. Samples were taken at 0, 30, and 60 minutes. Each sample was washed with 10 percent sodium carbonate solution, dried, and analyzed for nitrosamine content. The results were as follows:
time when sample taken nitrosamine concentration min. 60 min.
32.6 ppm. 2.9 ppn.
N.D.
EXAMPLE 4: NITROSAMINE REMOVAL FROM BENEFIN, 38% HYDROCHLORIC ACID
Benefin (15 grams), containing 130 ppm. of nitrosamine, was heated to 70“C. Concentrated (38%) hydrochloric acid (1.5 gram) was added and the reaction mixture was stirred for 15 minutes. The organic layer was separated and washed with a 10% sodium carbonate solution. The nitrosamine content of the resulting product was 17 ppm.
EXAMPLE 5: NITROSAMINE REMOVAL FROM BENEFIN, HCL GAS
Benefin (25 grams), containing 130 ppm of nitrosamine, was heated to 70eC. HCl gas was bubbled through at a rate of 8-12 ml./min. Samples were taken at 10, 20, 30 minutes. Each sample was washed with 10 percent sodium carbonate solution and analyzed for nitrosamine content.
The results were as follows:
time when sample taken nitrosamine concentration min 20 min 30 min ppm, 38 ppm. 14 ppm.
EXAMPLE 6: NITROSAMINE REMOVAL FROM ETHALFLURALIN, HCL
GAS
Ethalfuralin (100 grams) was heated to 70°C. HCl gas was bubbled through at a rate of 90 ml./min. Samples were taken periodically. Each sample was washed with 2 ml. of 10% sodium carbonate solution, dried, and analyzed for nitrosamine content. The results were as follows:
time when sample taken nitrosamine concentration min. 30 min.
hour
.2 ppm
N.D.
N.D.
N.D.
EXAMPLE 7: NITROSAMINE REMOVAL FROM TRIFLURALIN, FASTER
RATE OF ADDITION OF HCL GAS
Trifluralin (50 grams) was washed with water for 30 minutes, and air-dried for 30 minutes. It was then heated to 70°C. and HCl gas bubbled through at a rate of 35 ml./min. Samples were taken at 0, 15, 30, and 60 minutes. Each sample was washed with 10% sodium carbonate and analyzed for nitrosamine content. The results were as follows:
47137 time when nitrosamine sample taken_concentration
0 9 15 min. <1 30 min. <1 1 hour <1
EXAMPLE 8: NITROSAMINE REMOVAL FROM TRIFLURALIN, HCl GAS, EFFECT OF ADDED HgO
Trifluralin (100 grams) was heated to 70°C. and 0.5 ml. of water was added. HCl gas was then bubbled in at a rate of 8 ml./min. Samples were taken periodically; each was washed with 10 percent sodium carbonate solution, dried, and analyzed for nitrosamine content. The results were as follows:
time when sample taken nitrosamine concentration 0 27 ppm. 10 min. 14 ppm. 20 min 6.8 ppm. 30 min. 3.2 ppm. 45 min. N.D.
EXAMPLE 9: NITROSAMINE REMOVAL FROM TRIFLURALIN, HCL GAS
OVER LONGER TIME
Trifluralin (100 grams) was heated to 70°C. HCl gas was bubbled through at a rate of 8-12 ml./min. Samples were taken every 2 hours. Each sample was washed with 10% sodium carbonate solution, dried and analyzed for nitrosamine content. The results were as follows;
time when sample taken hours 4 hours 6 hours 8 hours nitrosamine concentration ppm. N.D.
N.D.
N.D.
1.3 ppm.
EXAMPLE 10: NITROSAMINE REMOVAL FROM ETHALFLURALIN, 38%
HYDROCHLORIC ACID
Ethalfluralin (85 grams), containing 9 ppm. of nitrosamine by TEA analysis, was heated to 70°C.; concen5 trated hydrochloric acid (38%; 15 grams) added, and the reaction mixture stirred for 30 minutes. The layers were separated and the organic layer was washed with 15 ml. of water. The layers were again separated and the organic layer washed with 15 ml. of 10% sodium carbonate solution
XO and then with 15 ml. of water. The organic layer was dried at 120°C. for 15 minutes. A sample was analyzed by TEA; no nitrosamine was detected.
EXAMPLE 11: NITROSAMINE REMOVAL FROM TRIFLURALIN, HCL
GAS, FASTER RATE OF ADDITION
. Trifluralin (50 grams), containing 18 ppm. of nitrosamine, was heated to 70°C. HCl gas was bubbled in at a rate of 90 ml./min.· for 5 minutes. The trifluralin was then washed with 5 ml. of 10% sodium carbonate and dried. A sample analyzed for nitrosamine content showed none detectable
EXAMPLE 12: NITROSAMINE REMOVAL FROM TRIFLURALIN, 38%
HYDROCHLORIC ACID OVER LONGER TIME
Trifluralin (60 grams) was heated to 70°C. Concentrated hydrochloric acid (38%, 6 grams) was added and the reaction mixture stirred. Samples were taken at intervals and analyzed for nitrosamine content. The results were as follows:
;4 time when sample taken nitrosamine concentration min.
hour hours
1/2 hours hours ppm
1.4 ppm.
1.5 ppm. <1 ppm.
1.4 ppm. 1.4 ppm.
EXAMPLE 13: NITROSAMINE REMOVAL FROM TRIFLURALIN, HCL
GAS AT HIGHER TEMPERATURE Trifluralin (100 grams) was dried for 30 minutes at 120°C. with air blowing over the surface. HCl gas was then passed through at a rate of 12 ml./min. and a temperature of 85°C. Samples, each 10 grams, were taken at 20, 40, 60, and 90 minutes. Each sample was washed with 5 ml. of 5% sodium carbonate solution and dried on a rotary evaporator for 15 minutes at 90°C. Results were as follows:
time when sample taken nitrosamine concentration
11.1 ppm.
min. N.D. 40 min. N.D. 60 min. N.D. 90 min. N.D.
EXAMPLE 14: NITROSAMINE REMOVAL FROM ISOPROPALIN, HCL
GAS AND ELEVATED PRESSURE
To 1 liter of a xylene solution of isopropalin (representing about 700 grams of isopropalin containing by TEA analysis 22 ppm. of nitrosamine) gaseous HCl was added to a pressure of 5 psig and at a temperature of 70°C. Samples were periodically withdrawn; each was washed with 50% by volume of a 5% sodium carbonate solution, the layers ;s separated, and the organic layer dried for 10 minutes at 60°C. on a rotary evaporator. The results by TEA analyses were as follows:
time when nitrosamine sample taken_concentration
22 ppm.
min. .22 ppm.
min. .19 ppm.
min. .4 ppm.
120 min. .52 ppm.
hours, 30 min. .40 ppm.
hours .28 ppm.
hours, 30 min. .24 ppm.
EXAMPLE 15: NITROSAMINE REMOVAL FROM ETHALFLURALIN, HCL
GAS
Ethalfluralin (100 grams), containing 10.5 ppm. of nitrosamine, was heated to 70“C. and HCl gas was bubbled in at a rate of 8 ml./min. Samples were removed periodically and analyzed for nitrosamine content by the thermal energy analyzer. Results were as follows:
time when nitrosamine sample taken_concentration
min. 10.9 ppm. 20 min. 6.6 ppm. 30 min. N.D. 40 min. N.D.
EXAMPLE 16: NITROSAMINE REMOVAL FROM TRIFLURALIN, 38%
HYDROCHLORIC ACID RECYCLED
Trifluralin (100 grams), containing 18 ppm. of 30 nitrosamine, was heated to 70°C. and 20 grams of 38% hydrochloric acid was added. The reaction mixture was stirred at 70°C. for 30 minutes. The layers were then separated. The organic layer was washed with 10 ml. of 10% sodium carbonate solution and analyzed for nitrosamine concentration. The acid layer was saturated with HCl gas and used in another ;6 nitrosamine reaction with another 100 grams of trifluralin, conducted under the same conditions as described above (the first recycle). Two more recycles of the acid were made. Results were as follows:
Nitrosamine
Sample Concentration control (starting 18 ppm.
trifluralin) first acid treatment N.D.
first recycle N.D.
second recycle N.D.
third recycle N.D.
EXAMPLE 17: NITROSAMINE REMOVAL PROM TRIFLURALIN, HCL
GAS AND ELEVATED PRESSURE IN PILOT PLANT RUN
Trifluralin (210.0 kilograms, was melted overnight (about 20 hours) at 70°C. and charged into a 75 gallon glass-lined still. The trifluralin was then heated to 90°C. and HCl gas passed in under pressure. The reaction conditions were as follows:
HCl Nitrosamine
Time Temp. (C) psig Sample ♦ Concentration
0 90° 0 #1 22 ppm 8 min. 91 2.5 #2 3 ppm 16 min. 90 2.5 #3 N.D. 22 min. 89 2.5 #4 N.D. 39 min. 90 2.5 #5 N.D. 65 min. 90 2.5 ' #6 N.D. 71 min. 90 2.5 #7 N.D.
Thereafter the reaction mixture was neutralized with sodium carbonate and another sample taken; no nitrosamine could be detected.
Total HCl used was 0.38 kilogram.
: I
EXAMPLE 18: NITROSAMINE REMOVAL FROM TRIFLURALIN, HCL
GAS, ETHANOL SOLVENT
HCl gas was bubbled (12 ml./min.) into a mixture of trifiuralin (50 ml.) and ethanol (25 ml.) at 70°C.
Samples were taken at 30 minutes and at 1 hour. Each sample was worked up by stripping on a rotary evaporator for 15 minutes at 30°C., and then washing with 5 ml. of 5 percent sodium carbonate solution. The layers were separated and the organic layer was stripped on a rotary evaporator for 15 minutes at 90°C. Results were as follows:
time when nitrosamine sample taken_concentration
44 ppm.
min. 20 ppm.
min. 14 ppm.
EXAMPLE 19: NITROSAMINE REMOVAL FROM TRIFLURALIN, TWO
TREATMENTS WITH 38% HYDROCHLORIC ACID Trifiuralin (20 grams), containing 68 ppm. of nitrosamine, and 5 ml. of 38% hydrochloric acid were mixed and held with stirring at 70°C. for 20 minutes. The layers were then separated, and to the organic layer, another 5 ml. of 38% hydrochloric -acid were added. The reaction mixture was again maintained at 70°C. for 20 minutes with stirring. The layers were separated and the organic layer washed with 10 ml. of 10% sodium carbonate. The product was analyzed for nitrosamine content. None was detectable by gas chromatography or TEA.
EXAMPLE 20: NITROSAMINE REMOVAL FROM DINITRAMINE, HCL GAS Dinitramine (10 grams of a sample containing
138 ppm of nitrosamine) was heated to about 110°C. and HCl ;8 gas added at a rate of 35 ml./min. for 45 minutes. After a 2 gram sample (labelled Sample 1) was removed, the hot remaining liquid was added slowly to 60 ml. of methylene chloride. 15 ml. of 10 percent sodium carbonate solution was added. The organic phase was separated and solvent removed from it on a rotary evaporator for 15 minutes at 45°C., yielding 8 grams of yellow solid (labelled Sample 2).
Each sample was analyzed for nitrosamine content by TEA. Results were as follows:
Nitrosamine
Concentration
Claims (12)
1. CLAIMSs1. A process which comprises (1) contacting a nitrosamine-containing dinitroaniline selected from trifluralin, isopropalin, benefin, ethalfluralin, butralin, tend imethalin, fluchloralin, profluralin, dinitramine, 4-trifluromethyl -2,6-dinitro-3-chloro-N,N-diethylaniline, 4-methyl-2,6-dinitro-N,N-bis(2-chloroethyl)aniline, oryzalin, and nitralin, (a) in liquid phase (b) with 20—30% hydrochloric acid or gaseous HCl until the concentration of the nitrosamine has been reduced; and (2) thereafter recovering the dinitroaniline.
2. The process of claim 1 wherein the dinitroaniline is selected from the trifluralin, isopropalin, benefin and ethalfluralin.
3. The process of claim 1 or 2 wherein the temperature is between room temperature and 140°C.
4. The process of claims 1 ( 2 or 3 wherein the temperature is from 70°C. and 90°C.
5. The process of any of claims 1 to 4· wherein the molten dinitroaniline constitutes the liquid.
6. The process of any of claims 1 to 4 wherein the process is conducted with a primary alcohol, ketone or aliphatic or aromatic hydrocarbon solvent
7. The process of any of claims 1 to 6 wherein the reagent is 33 to 38% hydrochloric acid.
8. The process of any of claims 1 to 5 wherein the reagent is gaseous HCl.
9. The process of claim 8 wherein the gaseous HCl is under a pressure of 1-10 psig.
10. The process of claim 9 wherein the pressure is 3-5 psig.
11. The process of any of claims 1 to 5 which comprises (1) contacting molten trifluralin with gaseous HCl at 70° to 90°C. at 2-5 psig until the concentration of the nitrosamine has been reduced j and (2) thereafter recovering the trifluralin.
12. · The process of any of claims 1 to 5 which comprises (1) contacting molten trifluralin with 38% HCl at 70° to 90°C. until the concentration of the nitrosamine has been reduced; and (2) thereafter recovering the trifluralin. ~ 1 (.. » 3.3. A process for reducing nitrosamine concentration and recovering the dinitroaniline as defined in claim 1 substantially as hereinbefore described in any of Examples 1 to 20.
Applications Claiming Priority (2)
Application Number | Priority Date | Filing Date | Title |
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US81655877A | 1977-07-18 | 1977-07-18 | |
US87883478A | 1978-02-17 | 1978-02-17 |
Publications (2)
Publication Number | Publication Date |
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IE781430L IE781430L (en) | 1979-01-18 |
IE47127B1 true IE47127B1 (en) | 1983-12-28 |
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Application Number | Title | Priority Date | Filing Date |
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IE1430/78A IE47127B1 (en) | 1977-07-18 | 1978-07-17 | Purification of dinitroanilines by removal of nitrosamine impurities |
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JP (1) | JPS5822102B2 (en) |
AR (1) | AR221846A1 (en) |
AU (1) | AU516698B2 (en) |
BG (1) | BG34182A3 (en) |
BR (1) | BR7804599A (en) |
CA (1) | CA1081256A (en) |
CS (1) | CS203196B2 (en) |
DD (1) | DD137222A5 (en) |
DE (1) | DE2831119C2 (en) |
DK (1) | DK152113C (en) |
ES (1) | ES471821A1 (en) |
FR (1) | FR2398044A1 (en) |
GB (1) | GB1599930A (en) |
HU (1) | HU182483B (en) |
IE (1) | IE47127B1 (en) |
IL (1) | IL55142A (en) |
IT (1) | IT1097822B (en) |
MX (1) | MX5203E (en) |
NL (1) | NL189911C (en) |
PL (1) | PL119759B1 (en) |
RO (1) | RO75656A (en) |
Families Citing this family (8)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
DE3061492D1 (en) * | 1979-05-21 | 1983-02-03 | Hoechst Ag | Process for the removal of nitrozation agents from nitrated aromatic compounds |
DE2926947C2 (en) * | 1979-07-04 | 1982-03-18 | Hoechst Ag, 6000 Frankfurt | Process for removing nitrosating agent (s) from nitrated aromatic compounds |
DE3345157A1 (en) * | 1983-12-14 | 1985-06-27 | Hoechst Ag, 6230 Frankfurt | METHOD FOR PRODUCING NITROSAMINE-FREE N, N-DISUBSTITUTED NITROAROMATIC AMINES AND THEIR STABILIZATION AGAINST NITROSAMINE FORMATION |
IT1195822B (en) * | 1986-08-12 | 1988-10-27 | I Pi Ci Spa | TRIFLURALINE PURIFICATION PROCEDURE |
IT1293450B1 (en) * | 1997-07-14 | 1999-03-01 | Finchimica Srl | DINITROANILINE PURIFICATION PROCEDURE. |
CN107106970B (en) | 2015-01-07 | 2020-06-09 | 三菱日立电力系统株式会社 | Method and apparatus for treating nitroso compound |
CN109320424B (en) * | 2017-07-31 | 2021-12-21 | 江苏永安化工有限公司 | Method for purifying pendimethalin |
CN116735760B (en) * | 2023-08-16 | 2024-02-09 | 山东道可化学有限公司 | Method for detecting N, N-dipropyl nitrosamine in trifluralin |
Family Cites Families (1)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US4134917A (en) * | 1977-04-25 | 1979-01-16 | American Cyanamid Company | Method for the denitrosation of organic nitrosamines |
-
1976
- 1976-07-14 RO RO7694675A patent/RO75656A/en unknown
-
1978
- 1978-05-31 GB GB25279/78A patent/GB1599930A/en not_active Expired
- 1978-07-14 NL NLAANVRAGE7807576,A patent/NL189911C/en not_active IP Right Cessation
- 1978-07-14 IT IT25724/78A patent/IT1097822B/en active
- 1978-07-14 IL IL55142A patent/IL55142A/en unknown
- 1978-07-14 DE DE2831119A patent/DE2831119C2/en not_active Expired
- 1978-07-14 HU HU78EI798A patent/HU182483B/en unknown
- 1978-07-14 AU AU38058/78A patent/AU516698B2/en not_active Expired
- 1978-07-14 CA CA307,403A patent/CA1081256A/en not_active Expired
- 1978-07-14 BG BG7840406A patent/BG34182A3/en unknown
- 1978-07-14 CS CS784725A patent/CS203196B2/en unknown
- 1978-07-17 ES ES471821A patent/ES471821A1/en not_active Expired
- 1978-07-17 DK DK319378A patent/DK152113C/en not_active IP Right Cessation
- 1978-07-17 IE IE1430/78A patent/IE47127B1/en not_active IP Right Cessation
- 1978-07-17 BR BR7804599A patent/BR7804599A/en unknown
- 1978-07-17 MX MX787265U patent/MX5203E/en unknown
- 1978-07-17 FR FR7821173A patent/FR2398044A1/en active Granted
- 1978-07-18 PL PL1978208500A patent/PL119759B1/en unknown
- 1978-07-18 DD DD78206786A patent/DD137222A5/en not_active IP Right Cessation
- 1978-07-18 JP JP53088257A patent/JPS5822102B2/en not_active Expired
- 1978-07-18 AR AR272995A patent/AR221846A1/en active
Also Published As
Publication number | Publication date |
---|---|
AU516698B2 (en) | 1981-06-18 |
ES471821A1 (en) | 1979-10-01 |
PL119759B1 (en) | 1982-01-30 |
NL189911B (en) | 1993-04-01 |
CS203196B2 (en) | 1981-02-27 |
AU3805878A (en) | 1980-01-17 |
AR221846A1 (en) | 1981-03-31 |
GB1599930A (en) | 1981-10-07 |
DE2831119C2 (en) | 1983-05-26 |
IE781430L (en) | 1979-01-18 |
DK319378A (en) | 1979-01-19 |
JPS5822102B2 (en) | 1983-05-06 |
IT1097822B (en) | 1985-08-31 |
IL55142A0 (en) | 1978-09-29 |
NL189911C (en) | 1993-09-01 |
RO75656A (en) | 1981-04-20 |
IL55142A (en) | 1981-06-29 |
DK152113B (en) | 1988-02-01 |
FR2398044B1 (en) | 1980-10-31 |
FR2398044A1 (en) | 1979-02-16 |
PL208500A1 (en) | 1979-07-02 |
BG34182A3 (en) | 1983-07-15 |
HU182483B (en) | 1984-01-30 |
CA1081256A (en) | 1980-07-08 |
DD137222A5 (en) | 1979-08-22 |
IT7825724A0 (en) | 1978-07-14 |
JPS5422329A (en) | 1979-02-20 |
DE2831119A1 (en) | 1979-02-08 |
MX5203E (en) | 1983-04-25 |
DK152113C (en) | 1988-06-20 |
BR7804599A (en) | 1979-03-20 |
NL7807576A (en) | 1979-01-22 |
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