2,410,101 Petented Oct. 29, UNITED STATES PATENT OFFICE WAX-FREE PYRETHRIN‘ SOLUTIONS ' Joseph D. Park, Wilmington, Del., and William W. Rhodes, Westtown, Pa., assignors to Kinetic Chemicals, Inc., Wilmington, Del., a corpora tion of. Delaware No Drawing. Application January 6, 1944, Serial No. 517,260 3 Claims. (Cl. 167-24) 2 1 waxes took place at room temperature. .The so lution was then ?ltered through Filter-eel on ?l ter cloth at room temperature in a closed sys tem, using the pressure of the solvent, with addi This invention relates to solutions 01’ pyrethrins which are stable in the presence of iron. Solutions of pyrethrins, the active ingredients of pyrethrum ?owers, are mixed with liquids vola tilizable at normal atmospheric temperatures and 5 tional nitrogen pressure if desired. The insoluble material removed amounted to 10% of the total enclosed in containers having ori?ces through weight of extract used. Part 01 the ?ltered solu which the contents may be discharged at will as tion was then placed in another pressure tube in a ?ne spray. The containers are usually made of ' contact with iron. After ?ve days’ standing, pre iron because the volatility of the propellant liq uid requires a container capable of withstanding 10 cipitation of dark and gummy substances began to take place on the iron while the original ?ltered pressure. The propellant solutions are usually solution in another pressure tube in the absence made up from standard pyrethrin extracts and, or iron remained unchanged. A portion or this after mixture with the propellant liquid, contain original ?ltered solution was then subjected to about 93% by weight of CClzFz as the propellant, about 1% oi.’ pyrethrins 1 and 2, about 4% kero 15 cooling at -—15° for one-half hour and ?ltered at the same temperature. Precipitation of insoluble sene and inert ingredients, and about 2% sesame waxes and fatsamounting to an additional 10% oil. The mixture of the pyrethrin solution with of the total extract used was obtained. This so CClzFr usually results in the precipitation of a lution remained clear in the presence of iron waxy material which is ?ltered oil to prevent it from clogging the ori?ce of the container. The 20 even- after a year’s standing. This experiment indicates the advantage of our invention. ?ltrate, when enclosed in an iron container, pre cipitates additional amounts of waxy material up Example II on standing. These additional amounts of waxy Kerosene extract of pyrethrum oleoresin ob material are sufficient to clog the type of ori?ce 25 tained by extraction of pyrethrum ?owers with used to produce an effective spray. ethylene dichloride was made up to the stand It is an object of this invention to prepare pro ard CClzFz aerosol solution as given in Example pellant solutions of pyrethrins which are stable I. Immediate precipitation of waxes and resin in the presence of iron. Other objects or the ous material took place. However, treatment of invention are in part apparent and will be in part 30 this solution by chilling to —15° for‘ one-halt set forth hereinafter. The objects of the invention are accomplished, _ hour and ?ltration at this temperature, brought about wax elimination to such an extent that further precipitation did not occur in the pres ence of iron. Various commercial grades 01' 20% generally speaking, by subjecting the propellant solution to a temperature between about —10° and about —30° C. until the wax precipitation has ceased, and ?ltering the wax from the chilled 35 pyrethrum extracts when used in CClzFz insec ticidal solutions behaved similarly. Subsequent solution. The solution so prepared is stable in cooling for one-half hour and ?ltering at —,-15° the presence of iron. C. brought about the elimination of any further The following examples illustrate the invention wax precipitation when cooled to -—20° C. or but do not limit it.‘ ' 40 when allowed to remain in iron cylinders for Example I months. In the practice of our invention the loss of the active ingredients pyrethrins I and 11 De?nite amounts of a commercial grade of par did not exceed over 1% of the total active ingre tially dewaxed 20% kerosene extract of pyreth dients originally present in the extract used. rum ?owers containing sesame oil were placed A very satisfactory operating temperature is in a high-pressure glass vessel and the vessel about —15° C., at which a cooling time of about then evacuated. Sufficient CClzF: was then add thirty minutes produces an e?lcient precipitation ed to make an insecticidal solution of the follow of waxes to produce a. ?ltrate stable in the pres ing composition: ' ence of iron. Chilling and ?ltering may be car Per cent by weight 50 ried out batchwise or continuously. Various con CClzF: __ 93 centrations of pyrethrins in the propellant solu Pyrethrins I and II_____________________ __ 1 Sesame oil. Inert+kerosene ' _____________ __- _________ __ tions may be used. 2 Immediate precipitation of insoluble fats and ' A particular advantage of the invention is that 4 propellant solutions of pyrethrins and propellants, 55 particularly CClzFa, are prepared which are sta 2,410,101 3 ble in the presence of iron. Insecticide contain ers having spray ori?ces contain these solutions without the precipitation of deleterious amounts of waxes‘ The propellant solutions before the treatment contain a coloring matter which pro duces undesirable green stains on cloth. An ad 4 2. The process of preparing propellant solutions of pyrethrins in CClaFa which are stable in the presence of iron, which comprises mixing a com mercial grade of a kerosene extract 01' pyrethrum ?owers with (301215’: in an amount su?‘lcient to make an insecticidal solution containing about 93% by weight of CClzF'a, chilling the resultant ditional advantage oi’ the invention is that this solution to between about ——10° C. and about treatment also removes that coloring matter. —30° C. until wax precipitation has ceased and As many apparently widely different embodi then separating the chilled solution from the pre ments of this invention may be made without cipitate. ' departing from the spirit and scope thereof, it is 3. The process of preparing propellant solutions to be understood that we do not limit ourselves to the speci?c embodiments thereof except as de of pyrethrins in CClzFa which are stable in the . presence of iron, which comprises mixing a com ?ned in the appended claims. 15 mercial grade of a kerosene extract of pyrethrum We claim: 1. The process of stabilizing a propellant so ?owers with CClaFs in an amount su?lcient to make an insecticidal solution containing about lution of pyrethrins in CCiaF: which solution nor mally tends to precipitate waxes and fats in the 93% by weight oi CClaFz, chilling the resultant presence oi! iron at temperatures above -20° 0., solution to about —15° C. until wax precipitation which comprises the steps 01' chilling the solution 20 has ceased and then separating the chilled solu tion from the precipitate. to between about —-10° C. and about —-30° C. until wax precipitation has ceased and then sep JOSEPH D. PARK. arating the chilled solution from the precipitate. WILLIAM W. RHODES‘.