US 3645693 A
Electrophile compounds used as intermediates or pesticides can be detected by forming volatile derivatives of said compounds by treatment with N-alkylformamides producing isocyanide ions which contact an inert support medium, then treating said medium and its contents with a detector agent for said ions thus producing the color detector signal for said ions.
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Description (OCR text may contain errors)
United States Patent Poziomek et al.
1 Feb. 29, 1.972
 CHEMICAL DETECTOR  Inventors: Edward J. Poziomek, Bel Air; Eleanor V.
Crabtree, Towson, both of Md.
 Assignee; The United States of America as represented by the Secretary of the Army 22 Filed: Nov. 3, 1969 21 AppLNos 373,107
 US. Cl. ..23/230 R, 252/408  Int. Cl ..Go1n 21/12, GOln 31/22  Field 01 Search ..23/230; 252/408; 260/465 A,
[ 5 6] References C ited UNITED STATES PATENTS 3,567,382 3/1971 Crabtree et al. ..23/230 3,405,160 10/1968 Eholzer et a1 ..260/46S A OTHER PUBLICATIONS l-lertler, W. R. et al., Journal of Organic Chemistry, Vol. 23, pp. 1221-2 1958) (P.0.S.L.).
Primary Examiner-Morris O. Wolk Assistant Examiner-Elliott A. Katz Attorneyllarry M. Saragovitz, Edward J. Kelly, Herbert Berl and Jacob Ziegler  ABSTRACT 6 Claims, No Drawings CHEMICAL DETECTOR DEDICATORY CLAUSE The invention described herein may be manufactured, used, and licensed by or for the Government for governmental purposes without the payment to us of any royalty thereon.
SPECIFICATION This invention is directed to the detection of electrophilic compounds which can be useful as intermediates in preparing other compounds or use in the agricultural field for detecting pesticides.
The object of this invention is the conversion of nonvolatile electrophiles to a more readily detectable volatile derivative of the electrophiles.
A general disadvantage of the former methods resides in that procedures require the determination to be carried out in liquid media, thus necessitating rather large masses of supporting equipment for solution detection and the manual handling of the sample containing the suspected compounds. The sample would have to be scraped or physically removed from the surface into aproper container for subsequent analysis in a solution procedure.
The advantage of our system lies in the minimum amount of handling the sample in view of the fact that the nonvolatile component is converted into a detectable volatile derivative. Thus the sample is no longer required to be removed from the surface for testing. The surface comprising the compound can be directly treated with the volatiling solution fonning a volatile component which is readily analyzed. Thus our system does not require physical handling of the sample, i.e., no scraping steps, and avoids any further contamination and can give greater weight to the validity of the results. In addition, inexperienced personnel can be employed since the usual chemical handling methods are no longer required.
A surface comprising about 0.1 to l.0p.g. of an electrophile is treated with about 10-100 1. of 1 normal N-loweralkylformamide and 100 .l. of a solvent, if desired, thus giving rise to the isocyanide ion in about 1 to 5 minutes. The isocyanide is adsorbed upon an inert support medium which is subsequently treated with a detector agent selected from the group consisting of benzidine and tetra base, producing a blue color detecting signal. If desired the inert support medium can be impregnated with the detector agent prior to exposure of the isocyanide ions, thus the support mediums blue color can be seen directly on the apparatus. The scheme, below, sets forth the general reaction of an electrophile with the aelimination giving rise to the corresponding isocyanide which is subsequently tested.
GENERAL SCHEME Wherein R or R, is an alkyl group, O-alkyl, S-alkyl or combinations thereof with the alkyl group containing from C to C carbon atoms.
X is oxygen or sulfur.
R, is hydrogen or an alkyl group from C to C, carbon atoms.
The more specific electrophiles are benzene sulfonyl chloride, toluene sulfonyl chloride, 0,0-dimethyl phosphorochloridothionate and diethylphosphorochloridate.
An interesting result from our studies is that all electrophiles do not give isocyanides in the presence of N-alkylformamides. Hoy et al., J. Org. Chem., 33, 4050 (1968) disclose the reaction between N-alkylformamide and electrophilic chemicals producing the imide. For example, a reaction N-butylformamide and acetyl chloride leading to N-(butyl)-N-formylacetamide.
As a result of our new method phosphorus-containing insecticide 0,0-dimethyl phosphorochloridothionate is readily detected in the field.
Tetra base reagent comprises mixing solutions of equal volumes of (a) 80-120 mg. of p,p -tetramethyldiaminodiphenylmethane and 400-600 mg. of salicylic acid in 100 ml. acetone and (b) 1.2-1.8 g. of cupric sulfate in 100 ml. of water. The preferred range is 100 mg. p,p'-tetramethyldiphenylmethane, 500 mg. salicylic acid and 1.5 g. cupric sulfate.
The benzidine reagent is mixed just prior to use, comprises equal volumes of (a) aqueous cupric acetate solution, 2.9453.43 g./ l. and (b) 675 ml. of benzidine acetate solution, saturated at room temperature, mixed with 525 ml. of water. The solutions (a) and (b) are best stored separately and in dark bottles. The preferred range for the aqueous cupric acetate is 2.86 g./l.
The use of silica gel tubes and the detecting apparatus for the isocyanide ion are well established in the open literature and may be employed according to the colorimetric method utilizing the described tetra base reagent or the benzidine reagent, Shepard, Anal. Chem., 19, 77, 1947; Williams et al.,
Anal. Chem., 34, 225, 1962; Crabtree et al., Talanta, 14, 857, 1967.
In general the silica gel tube is constructed as follows: A glass tube about 4 inches in length (3 mm. i.d.) containing an inert support medium, the untreated silica gel or treated silica gel, and then sealing off both ends of the glass tubing. The filling operations are those conventional in the art such as tamping the silica gel into the tube. Prior to use, each end of the filled tube is broken off and inserted in the various sampling apparatus.
When an unimpregnated silica gel detector tube is used, the isocyanide vapor is collected on the silica gel, the detector tube is removed from the apparatus, and the silica gel is moistened with a drop of either the benzidine or tetra base reagent. The appearance of a blue color is a positive test for the isocyanide.
The apparatus and the reagents we employed for the isocyanide detection are disclosed in copending patent application Ser. No. 723,487, filed 23 Apr. 1968. Now US. Pat. No. 3,567,382.
A solvent may be used, if desired, such as quinoline to facilitate the process, however, care must be taken that ethanol or dioxane are not employed since they interfere or inhibit the detection system.
EXAMPLE 1 a. A sample in a test tube comprising at least 0.2 g. of 0,0-
dimethyl phosphorochloridothionate, 100M. of N-methylfor- The latter tube is treated with about one drop (0.05 ml.) of the tetra base turning the silica gel blue indicating the presence of an isocyanide, thus demonstrating the original presence of an electrophile 0,0-dimethyl phosphorochloridothionate.
Higher concentrations of the phosphorus compounds are more readily detected and give rise to the isocyanide ion in a. short time.
h. The above procedure was repeated with the exception of utilizing the benzidine for the tetra base reagent.
EXAMPLE 2 The procedure according to Example I was followed with the exception of substituting other electrophiles of benzene sulfonyl chloride, toluene sulfonyl chloride or diethylphosphorochloridate for the phosphorochloridothionate giving rise to similar results, that is, a blue color with either the benzidine or tetra base reagent thus demonstrating the presence of electrophiles.
EXAMPLE 3 A surface comprising at least O.2 .g. of 0,0-
dimethylphosphorochloridothionate was treated with about EXAMPLE 4 The procedure according to Example 3 was followed with Y -Cl wherein Q is Q 0 E R X u P- or R or R is an alkyl group, O alkyl, S-alkyl or combinations thereof with the alkyl group containing from C l to C, carbon atoms.
X is oxygen or sulfur.
R is hydrogen or an alkyl group from C, to C; carbon atoms. in a reaction mixture comprising adding N-alkylformamide to produce volatile isocyanide ions, contacting an inert support medium with said isocyanide ions, treating said sup.- port medium and its contents with a detector agent for said isocyanide ions, producing the detector signal for said isocyanide ions and thereby indicating the presence of electrophiles.
2. The method according to claim 1, wherein Q is solution containing saturation benzidine acetate solution.
5. A method vaccording to claim 1, wherein the reaction mixture comprises a solvent.
6. A method according to claim 5, wherein the solvent is quinoline.