US2655460A - Dibasic silver salts of alkenyl sucicinic acids and method for combating fungus infestations therewith - Google Patents

Description

Patented Oct. 13, 1953 DIBASIC SILVER SALTS OF ALKENYL SUC- CINIC ACIDS AND METHOD FOR COMBAT- ING FUNGUS INFESTATIONS THEREWITH Mearl A.

Kise, Portsmouth, Va., assignor to Allied Chemical & Dye Corporation,

New York, N. Y.,

a corporation of New York N Drawing. Application December 1, 1949, Serial No. 130,601

8 Claims. (01. 167-22) This invention relates to new fungicidal compositions, to a method for preparing them and to a method for combating fungus infestations therewith.

In the past it has been the practice to control plant-infesting fungi by the application of sulfur-containing, copper-containing and other chemical fungicides.

An outstanding disadvantage in the use of chemical fungicides employed in the past has been that many such fungicides, when used in quantities or concentrations sufiiciently high, efiectively to control the particular fungus infestation, caused serious injury to the plant host.

It has long been known that silver in the form ofits inorganic salts such as silver nitrate, possesses outstanding germicidal and fungicidal properties.

However, silver salts have not heretofore been considered useful as fungicides since silver salts in general. e. g., silver nitrate, are known to be severely toxic to plants and hence not ractical as fungicides.

It is an object of the present invention to provide new fungicidal compositions containing sil ver wherein the active ingredients have unusually high fungicidal activity at acceptably low phytotoxicity levels.

This and other objects are accomplished according to my invention which provides new compositions wherein the dibasic silver salts of alkenyl succinic acids having from 4 to 24 carbon atoms in the alkenyl group comprise the major active toxicants, and a method for combating fungi by applying such compositions to the host.

The dibasic silver salts of alkenyl succinic acids of the present invention may be represented by the formula to 24 carbon atoms inclusive. The alkenyl group may contain straight or branched chains.

The silver salts above described may be prepared from the corresponding alkenyl succinic acid anhydride through the corresponding Watersoluble dibasic alkali metal salts according to the following reactions wherein R is an alkenyl group containing from 4 o R-CH-COONa R--CHCOOAg 2N8, Hr-C O O No (as water- Hz-C 0 0 Ag soluble salt) Alkenyl succinic acid anhydrides suitable for preparation of the dibasic silver salts employed in the compositions and method of the invention may be obtained'as described in U. S. Patent No. 2,411,215 of Mearl A. Kise and Robert F. Engle entitled Production of Substituted Succinic Anhydrides, by the reaction of maleic anhydride and a cracked distillate fraction containing aliphatic mono-olefins.

The dibasic silver salts of alkenyl succinic acids prepared from the acid anhydrides derived from cracked petroleum distillates, as described in the patent above referred to, are mixtures corresponding in alkenyl chain length to the chain length of the compounds present in the olefins of the distillate fraction. Such fractions or cuts may be taken containing the desired predominant number of carbon atoms in the chains, cuts containing predominantly 06-8, and Clo-l2 carbon atoms being preferred, and any of the cuts, or mixtures of the whole range or parts thereof, of compounds containing from 4 to 24 carbon atoms inclusive are satisfactory.

The dibasic silver salts of alkenyl succinic acids may be prepared by any suitable process, for example according to the above reactions. In carrying out the preparation, the dibasic alkali metal salt of the desired alkenyl succinic acid may be dissolved in water, or the aqueous reaction mass in which the dibasic alkali metal salt is formed may be used as such. To this solution there is added, with stirring and while protecting the mixture from exposure to light, a sufiicient quantity of a water-soluble silver salt, such as AgNOa in water solution, to displace the alkali metal of the dibasic alkali metal succinic acid with silver. A creamy, light gray mixture results which may be further diluted and stirred vigorously for an hour to insure completion of the displacement reaction. The dibasic silver salt of the alkenyl succinic acid thus produced is a solid at normal room temperatures. and may be isolated and freed from impurities, e. g., sodium nitrate, etc., by mechanical separation such as filtration, centrifugation or the like, and washing with water to eliminate water-soluble impurities. The silver salt may then be dried and powdered.

The dibasic silver salts of alkenyl succinic acids of the type contemplated herein are new compositions of matter. They are white, crystalline solids, only slightly soluble in water, and are relatively insoluble in acetone and benzene, and vary in molecular Weights from about 386 for salt of alkenyl These salts tend to exhibit a slight darkening.

on exposure'to light, which does not materially afiect their fungicidal characteristics if not unduly prolonged. When stored in brown glass containers or in other manner so as to exclude substantial amounts of light, the salts are sufficiently stable for commercial requirements, usually exhibiting no appreciable deterioration on storage over periods of at least a year. The dibasic silver salt of a single alkenyl succinic acid may be used in the fungicidal compostions of my invention or a mixture of such salts may be employed as brought out above. Particularly suitable mixtures are those in which the alkenyl groups contain predominantly 6-8 carbon atoms and 10-12 carbon atoms respectively. Examples showing typical procedures for the preparation of the silver salts of alkenyl succinic acids are set forth below (parts are by weight) Example 1 Fifty-four parts of an alkenyl succinic acid anhydride in which the alkenyl group consisted chiefly of C1042 radicals was heated to ISO-4.0v C. and 15.8 parts of sodium hydroxide in the form of a 2.11 normal aqueous solution was added thereto over a 10 minute period. The mixture was heated at 100 C. with stirring for 1.8 hours, then cooled to 25 C. The solution was protected from light and 70.72 parts of AgNOs in 250 parts of water were added with stirring over a minute period. The creamy, light gray mixture which resulted was diluted with 200 parts of water and stirred vigorously for one hour. The mixture was then filtered and washed with distilled water until washings were (N03) -free, with precautions taken to protect from light. The damp filter cake was dried at low pressure over CaClz, powdered and bottled. The yield was 92.76 parts, equivalent to about 92.8% of theoretical. The material analyzed 41.97% silver compared to 42.75% theoretical.

Example 2 491 grams (2.5 mols) Ce-a alkenyl succinic acid anhydride having a neutral equivalent of 98.2 was cooled to l0-l5 C. and 2500 ml. of 2 N sodium hydroxide was added slowly. The mixture was heated at 85 C. with stirring for 1 hour. The solution was neutralized with 0.25 N H2804 and added with stirring to 892 grams of AgNOz dissolved in 2500 ml. of water. The silver salt precipitated. The mixture was protected from light, and after one hour standing was filtered and product washed with liters of distilled water. The damp filter cake was dried at 55 C. at low pressure. Yield: 900 g.; analysis 50.43% Ag; theory 50.39% Ag. Calculated average molecular weight 428.2.

The new silver salts of my invention exert outstandingly toxic ellects against a number of fungus organisms heretofore difficult to control. As will appear from the tabulated data hereinafter set forth, this activity is evident at unusually low concentration levels such that danger to the plant is not a hazard, even at concentration levels sufiicient to insure complete control of the organisms. Thus, effective fungicidal protection is afforded against early potato blight (Alternaria solani) when applied at the rate of one-eighth pound of salt per 100 gallons of spray; against black rot of sweet potatoes (Ceratostomella fimbriata) by the use of water suspensions containing as little as 0.025% of the silver salt when used as a sprout dip; against brown rot (Sclerotinia fructz'cola) of fruit trees and against apple scab (Venturia) both the latter-at concentration of less than one part per million of solution. Virtually complete salts in compositions containing a major proportion of a diluent or carrier material of low or negligible phytotoxicity, either as dusts. or as liquid sprays 'or dips. In the preparation of liquid compositions, water may conveniently be used since it is a cheap and effective diluent and carrier, and readily disperses the silver salts or my invention. Other well-known spray amendments may be used in my compositions such as wetting, sticking and spreading agents and the like, and other antiparasitic materials may be added, for example, to control pests other than fungi.

Fungicidal and phytocidal tests were carried out using the particular dibasic silver salts of alkenyl sucoinic acids of my invention indicated in the tables below, and with the results there set forth.

In Table I are recorded the LB-50 values (i. e., the doses required to effect 50% controlof the fungus) obtained as results of a series of tests against the organisms Sclerotim'a Jructicola, AZ- ternario solani and Venturia in which successively decreasingconcentrations of a dibasic silver salt of a C1042 alkenyl succinic acid were used in tests against spores of the organisms mentioned above to determine the minimum concentration of silver salt in parts per million in water necessary to prevent 50% of the spores from germinating. The results are given in Table I below:

TABLE I LD-50 value of the dibasic silver salts of 010-12 alkenyl succinic acid in parts per million in water spray As is well known, fungicides having an LD-50 value below about 1,000 parts per million concentration are considered to be of value as fungicides. It is accordingly apparent that the silver salts of my invention are outstandingly toxic against various fungus organisms.

In order to indicate the non-toxic nature of the new fungicides toward the host at effective concentration levels, phytotoxi'city tests on tomato plants, one of the most sensitive of cultivated plants, results of which are recorded in Table II below, were carried out and indicate that no injury to the plant takes place by the application thereto of suspensions of my new silver salts at concentrations greatly in excess of the amount required for control of early and late tomato blight. It will be observed that no injury was apparent at a dosage of 04%, i. e. 400 parts per million silver salt concentration and severe injury was not inflicted until the dosage reached 0.2%, i. e. 2,000 parts per million,

6 conditions and with the results indicated in Table IV below:

TABLE IV Potato blight control Rate of application, lb./l00 gals. Percent tubers Yield Fungicidal composition Parts T t 1 showing bushels 0 a visible per acre mixture DDT other plight None... None... None 11. 8 180 }2lb llb do as 250 }'41b. .do 31b 6.0 330 1 basic Gas 04 1361b". d0. 0.125lb.Agselt 8.8 297 Dibasic Ag salt of 010- alkenyl succinic acid.

whereas less than a single part per million concentration aifords effective (LD-SO) fungus control.

TABLE II Phytotoxz'city of dibasic silver salts of 010-12 alkenyl succinic acids on tomatoes Black rot of sweet potatoes is readily controlled by low concentrations of the dibasic silver salts of my invention as indicated by tests carried out in Louisiana, results of which are reported in Table III below. In these tests, discs prepared from roots of the Puerto Rico variety of sweet potato were inocculated by spraying with a spore suspension of black rot fungus. Afterwards the inocculated discs were treated at the concentrations and for the periods of treatment listed below with a fungicidal dust prepared by mixing of the dibasic silver salt of a 06-8 alkenyl succinic acid with 75% clay, and suspending this dust in water in the concentrations indicated. Results, both as to fungus control and phytotoxicity, are given in Table III below:

TABLE In Control of potato blight is effected by application of the dibasic silver salts of alkenyl succinic acid to the host as indicated in Table IV below. In carrying out these tests in New Hampshire fields, the test mixtures were made up with a standard quantity of dichlorodiphenyltrichloroethane (DDT) to control insects at the same time, and the crop was given five separate applications by spraying the potato plant foliage under the From the above data, it will be apparent that the yield was increased 32% by the standard copper fungicide whereas the silver salt used at ,5 the concentration (metal basis) gave an increase of 19%.

I claim:

1. As new compositions of matter, the dibasic silver salts of alkenyl succinic acids having the general formula wherein R is an alkenyl group containing from 4 to 24 carbon atoms inclusive.

2. As new compositions of matter adapted for use as fungicides, mixtures comprising dibasic silver salts of alkenyl succinic acids having the wherein R represents in the several components or the mixture at least two diiferent alkenyl groups selected from alkenyl groups containing from 4 to 24 carbon atoms inclusive.

3. As a new composition of matter adapted for use as a fungicide. a mixture of dibasic silver salts of alkenyl succinic acids having the following general formula wherein R represents a plurality of alkenyl groups containing predominantly 6-8 carbon atoms.

4. As a new composition of matter adapted for use as a fungicide, a mixture of dibasic silver salts of alkenyl succinic acids having the following general formula wherein R represents a plurality of alkenyl groups containing predominantly 10-12 carbon atoms.

5. A method for combating fungus infestations on plants which comprises subjecting them to the action of a composition containing as the essential active toxicant a compound having the general formula wherein R. represents an al'kenyl group containing from 4 to 24 carbon atoms inclusive.

6. A method for combating fungus infestations on plants which comprises subjecting them to the action of a composition containing as the essential active toxicant a mixture of compounds having the general formula wherein R represents a plurality of alkenyl groups containing predominantly 6-8 carbons atoms.

7. A method for combating fungus infestations on plants which comprises. subjecting them to the action of a composition containing as the essential active toxicant a mixture of compounds having the general formula 8 wherein R represents a plurality of alkenyl groups containing predominantly 10-12 carbon atoms.

8. A process for combating fungoidblight of potato plant which comprises applying to the leaf surfaces of the potato plant an aqueous dispersion of the dibasic silver salt of an alkenyl succinic acid containing from 4 to 24 carbon atoms, inclusive, in the alkenyl group.

MEARL A. KISE.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 1,853,397 Banks Apr. 12, 1932 2,360,426 Kyrides Oct. 17, 1944 2,380,699 Kyrides July 31, 1945 2,381,852 Hochwalt Au 7, 1945 OTHER REFERENCES

Claims (2)

1. AS NEW COMPOSITIONS OF MATTER, THE DIBASIC SILVER SALTS OF ALKENYL SUCCINIC ACIDS HAVING THE GENERAL FORMULA

5. A METHOD FOR COMBATING FUNGUS INFESTATIONS ON PLANTS WHICH COMPRISES SUBJECTING THEM TO THE ACTION OF A COMPOSITION CONTAINING AS THE ESSENTIAL ACTIVE TOXICANT A COMPOUND HAVING THE GENERAL FROMULA