WARF: Wiscon Alumni Research Foundation

UNITED STATES PATENT OFFICE     2,783,177   Patented Feb.  26, 1957





Karl Paul LLink, Middleton, Wis.,assig'nor to Wisconsin

Alumni Research Foundation, Madison, Wis., a corpo-

‘ration of Wisconsin

No Drawing. Application March 17, 1952,

Serial No. 277,080

3 Claims. (Cl. 167-446)


The present invention ‘relates to improved rodenticide

compositions and ‘in particular rodenticide compositions

for use in the preparation of water baits. The composi

tions comprise an alkali metal salt of an anti-coagulant

4-hydroxycou-marin derivative in combination with inert

carriers of the type speci?ed below. These combinations

are ‘stable and, as compositions suitable ‘for use in the

/ water bait practice, are characterized by their unique

safety factor.


The 4-hydroxycoumarin derivatives suitable for use in

the present invention are the lit-substituted type disclosed

in ‘U. 8. Patent 2,427,578. These compounds are char

acterized by an enol-ic~..OH group at the 4-position and a



R ' 0


group at the 3-position, where the R’s represent lower

alkyl and phenyl groups including substituted phenyl

groups such as alkyl, alkoxy and halogen substituted

phenyl groups. Of the compounds in this group the

compound known as warfarin (3-(a-acetonylbenzyl)e4

hydroxycoumarin) is outstanding, and for purposes of il

.lustration the present invention is described with particu- _

lar reference to the alkali metal warfarinates. ,


The rodent problem has been recognized as serious for

many years. Rats and mice, for example, are known

to consume j_ and spoil large amounts of grain and other

foods, spread ?lth and disease, kill chickens and the like,

The U. S. Government estimates

that the rodents’ annual board bill runs into the hundreds

of millions of dollars, and, that the rodents destroy many

times what they eat. When one considers that this is

only'a part of the overall rodent bill paid by the public

along with the estimate that there are many millions ‘of

rats and mice in the United States, the magnitude of the

problem in this country alone is readily apparent.

Until the ‘discovery of the anti-coagulant, .Warfarin, it

had long been the established practice in the rodenticide

?eld to employ very toxic rapidly acting stomach poisons

of the “single dose” type such as strychnine or the more

recently proposed sodium ‘?uoroacetate. This latter prod

H_Ct,'k1‘lOWl'l as “1080,” is ‘extremely toxic and its use

is ‘restricted to the professional or licensed pest control

operators and the like. The use of poison substances of

this type, particularly in the water bait practice, poses

serious problems in use due to their equally toxic ‘effect

on humans and domestic animals. Also, investigations

inthe-rodenticide ?eld have shown that the rapidly act

ing poisons are not generally acceptable‘ to the majority

‘of the rodent colony, particularly after the toxic mani

festations are apparent in the relatively few rodents (of

?cial colony food tasters) who initially test the new baits.

This is known in the art as the development of “bait



With the development of warfarin a new concept—

multiple dose baits-was introduced into the rodenticide

?eld. Multiple doses of 'warfarin in relativelyminute

.amounts'i'n food baits, for example, have been found to

nited States Patent 0

.commercially only for use in food ‘baits.


Patented Feb. 26, 1957



produce high kills in both rats and mice within a few

days. See Ross, Ward, Agricultural Chemicals, October



Up to the present time warfarin has been available

It .has been sold as a concentrate made up of ‘0.5 part ‘by weight of

warfarin and 99.5 parts by weight of a diluent such as

corn starch, one part ‘of which mixed with 19 parts of

food provides a desired bait containing 0.025% by weight

of warfarin. Warfarin has also been sold as a ?nished

bait made up of 99.975 parts by weight of food such as

corn meal and 0.025 part by weight of warfarin. ‘While

compositions of this type haveproven outstanding as food

baits and are being used extensively today, the need for

a composition for use in the water bait practice and in

particular a relatively safe composition adaptable for use

by the public at large as distinguished from professional

exterminators, has urgently been desired by the rodenti

cide industry and by the users of rodenticides. In addi

tion ‘to eliminating food costs required for food baits,

Water baits ‘are also preferred in many applications in

rodenticide practice. Water‘baits, along with composi

tions used to prepare water baits,'for example, are rela

tively stable and in this ‘respect differ from ?nished food

baits which are subject to the inherent defects ‘of pack

aged foods, e, g, staling, rancidity, molding, insect fin

festation, etc., all of which can make the bait unpalatable

to the rodent. ‘See Ross, supra. Water baits ‘are partic

ularly desirable to control rodent population in and

around grainstorage elevators, mills,_grain and other food

processing establishments Where food ‘saturation exists

and where sources of water are not readily available to

the rodent. . jRodent ‘control in premises of this type is

particularly important in view of the very extensive rodent

contamination '(rat hair, feces, etc.) recently found to

exist in grain and products made from grain, especially

Wheat and corn, in long term research studies conducted

by the U. S. Food and Drug Administration. See Harris,

Kenton L., et al., An Investigation of Insect and Rodent

Contamination of _Wheat and Wheat Flour, Journal of the

Association of Official Agricultural Chemists, February,

1952. _ .


‘It is essential in thewater bait practice for the rodenti

cide compositions to be readily soluble in ‘cold water in

sut?cient amounts to produce high kills. ‘It is also essen

tial that the ‘resulting bait solutions be free from “olf

tastes” to be acceptable to the rodent. Warfarin itself

(along with the related 3-substituted-4-hydroxycouma

rins) is only very slightly soluble in water and goes into

solution with difficulty, vand is therefore not suitable for

use in water baits or compositions used to prepare water

baits. It has been found, however, that Warfarin can be

reacted with alkali metal hydroxides, such as sodium or

potassium hydroxide, without opening the lacton'e ring,

to form a water soluble salt 3-(u-acetonylbenzyl‘)4

hydroxycoumarin, sodium .derivative, .(referred "to herein

as the alkali metal salt of warfarin or alkali metal war

farinate), and that the resulting alkali metal salt is very

soluble in water, e. g., 60 grams of- sodiurn'salt per 100

cc. of water forms a stable solution at 25° C. 'It has also

been found that the alkali metal warfarinates are highly

toxic to rodents and when free from free alkali as Well

as degradation products which lend‘ taste ‘or odor to the

salts, are particularly adaptable for use in water baits ‘and

compositions used to prepare water baits. The salts

may be prepared by reacting warfarin with dilute aqueous

alkali solutions under conditions speci?ed vbelow. The

sodium salt, for example, is preferably made at room

temperature by reacting one mole of substantially pure

warfarin with slightly less than one mole of sodium hy

droxide in aqueous solution, ‘followed by removal of ex

cess warfarin by ?ltration. The sodium warfarinate ‘ob

2,788,177   tained by this procedure contains no free alkali or dele

terious degradation products and may be obtained in

solid form if desired by removal of the water by evapo

ration preferably under reduced pressure.


With the preparation of the alkali metal salts of war

farin free from free alkali, etc., satisfactorily solved and

their effect in water baits demonstrated, the problem of

getting the salts into a safe, practical form for marketing

only remained. This is ‘of utmost importance in the

rodenticide ?eld ‘as a practical rodenticide composition

should have a maximum safety factor as far as humans

and domestic animals are concerned and at the same

timebe readily adaptable for use with the minimum of

effort. Also the compositions should be stable in and

out of water, as baits containing materials which have

undergone deterioration are not readily acceptable to the



The marketing of the alkali metal warfarin salt per so

as a powder for addition to water was discarded as the

presence of large amounts of available warfarin in con- '

centrated form presented an extreme hazard to both hu

mans and domestic animals. Also, warfarin salts un

less free from free alkali tend to be hygroscopic in na

ture and cake, e. g., become glassy in character upon

storage in containers, making accurate measurements for ‘

addition to water dif?cult. To overcome some of these

disadvantages the use of capsules and tablets containing

the desired percentage of warfarin salt for addition to

speci?ed amounts of water were investigated. Aside

from the fact that trouble was encountered in preparing

satisfactory capsules and in obtaining stable tablets that

would dissolve readily when added to water, these routes

were also discarded due to the hazard involved in hav

ing concentrated warfarin available to humans and in

particular available in a form attractive to children.

There has also been investigated the distribution of con

centrated solutions of warfarin salts to be added to water

by the user and the distribution of a ?nal dilute water

bait ready for use “as is.” The former was discarded

due to the great hazard referred to above and the latter

was found impractical due to lack ‘of economy in han

dling and shipment of such large quantities of water,

breakage of containers if glass or the like is used, cor

rosion of metal containers, etc.


Many attempts were made to provide a practical ro

denticide composition adaptable for use in the prepara

tion of water baits having the desired safety factor for

use by the public at large. The challenge presented

resided in providing a satisfactory composition that would

have at least as high or better safety factor than the

warfarin concentrates suitable for making food baits and

the ?nished warfarin food baits. This involved among

other things the acceptability of ‘the resulting bait solu

tions, as baits which are not readily acceptable to the

rodent have proven in practice substantially worthless. -

The problem remained unsolved until I discovered the

compositions of the present invention comprising special

types of inert carriers characterized below in combina

tion with the alkali metal (alkali-free) salt of warfarin.

My investigations have demonstrated that the carrier

should be substantially odorless, tasteless, insoluble in

water and biologically and chemically stable. My in

vestigations have also demonstrated that the carrier should

be of the non-edible type and should be unsuitable for

poisoning of humans by intent, i. e. homicides or sui

cides. The characteristics--substantially odorless, taste_

less, etc.—-are essential to provide water bait solutions

acceptable to the rodent. In addition, the carrier should

not “bind” the salt of warfarin in solution, i. e., should

be such that the salt is readily‘ released and goes into

solution quickly when the mixture is added to water.

Particles of inert inorganic or mineral materials such‘

as sand have proven in practice to be satisfactory carriers.


While the salts of warfarin may be prepared in solid

form and then added to water for application to the

inert carrier, this is not necessary and the preferred and

most economical practice is to prepare the warfarinate

in solution form and then treat the carrier with the solu

tion as described below.



To 865 grams of distilled water 32.4 grams of sodium

hydroxide (analytical reagent minimum purity 97%) is

added and the mixture stirred until the sodium hydroxide

dissolves. To this solution is next added 250 grams of

rodenticide grade (substantially pure) essentially odor

less and ‘tasteless warwarin, and the resulting mixture

then stirred vigorously for about ten minutes until the

solution shows a pH of about 8.0 as tested, for example,

with Hydrion A pH paper. . A slight excess of warfarin

(5.0 grams of warfarin is satisfactory) is then ?nally

added to insure complete conversion of the sodium hy~

droxide to the sodium wartarinate and the solution ?l

tered with or without a ?lter aid. The excess (undis

solved) warfarin is recovered in the ?ltration operation

and may be reused for subsequent batches. The ?nal

clear solution contains approximately 23.4% by weight

of sodium warfarinate (or 21.8% by weight on the war

farin basis) and is ready for use in Example I as de

scribed below. Solutions of different warfarinate con

centrations up to approximately 60% may be readily pre

pared by varying the amounts of ingredients, although in

all cases, excess warfarin should be present in the reac

tion mixture to insure that the solutions contain no free

alkali for warfarin undergoes degradation on standing

in the presence of free alkali, with the rate of degrada

tion increasing materially at higher temperatures.

The following examples will serve to illustrate the pres

ent invention:


Y Example I

About 944.91 grams of a good quality of clean, washed

previously screened standard 20-30 mesh sand, is dried

at 95—100° C. for about three hours in a well ventilated

tray oven. To the dried sand after cooling is next added

slowly with stirring 20.0 cc. of a 21.8% by weight aque~

ous sodium warfarinate solution. The warfarinate-sand

mixture is then dried for about three hours at 50~60° C.

At the start of this drying operation, there is a tendency

for the surface of the sand mix to cake. This should

be broken up by stirring. After completion of the dry

ing operation the product is allowed to cool to room tem

perature and is then ready for packaging. _

The product obtained as described above contains

about 5.09 grams of sodium warfarinate which is equiv

alent to 4.75 grams of warfarin or about 0.5% by weight

of warfarin on a dry weight basis. About 9.5 grams of

the dry product thus contains about 47.5 mg. of warfarin

which, when added ‘to one quart of water (946.4 cc.)

with stirring, makes a satisfactory fountain bait con

taining about 0.05 mg. of warfarin per cc.


Example II

To about 938.82 grams of 20-40 mesh clean, washed

sea sand previously dried and cooled as-described in Ex

ample I, is added with stirring about 20.0 cc. of a 43.6%

by weight aqueous sodium Warfarinate solution. The

warfarinate-sand mixture is then dried as described in


Example I. The dry product obtained by the process

of Example II contains 1.0% by weight of warfarin ‘and

4.75 grams of this product added to one quart of water

also gives a satisfactory water bait containing about 0.05

mg. of warfarin per cc.




To about'500 ml. ‘of’ distilled water, add‘64;960 g.

(1.6240 moles) of analytical reagent sodiumhydroxide

(minimum purity 97%).‘ Stir the solution until, thesq

diurn hydroxide dissolves. To this alkaline‘ solution add





into‘ solution but some can be‘ reeeveréd ?ltration

find ire-risen ‘for subsequent batches; The resultant solu—'

tidn' is diluted to, 1000 ml. With distilled'watér and shaken

to‘ in are" complete,‘ mixing. The final solution is slight

1y greater than 5 0% by volume with respect to warfarin.


Example III

Ta about 19 grams of clean. washed ‘20-‘30 v‘mesh satin

previously dried as' described iii Example I is added with

stirring 2 cc. of a 50% by_,volume of aqueous sodium

wet-reiterate The‘ product ist ‘a ‘dried as described above

a d: ceht'ains' about 5% by Weight of Na-warfarinate.

one gram of this‘ product contains about 50 mg. of war‘

rann which when‘ added to 1 qt. water provides a ?nal

water’bait containing ab‘o'u't'0.05' of warfarin per cc.


Example IV

About 400 cc. of a 50% by volume of aqueous sodi

um warfarinate is sprayed on 1800 grams of clean, dry

20;‘5'0'in'e‘sh sand while the sand is vigorously tumbled in

an enclosed mixer. After‘ drying as‘ above the ?nal prod

uct? contains" about 10 %' by weight of sodium warfarinate

of which 0.5 gram added to one quart of water yields a

final water bait containing about 0.05 mg. of warfarin

per‘ cc‘. For‘pra'eti'cal purposes the carrying capacity‘of

sand has been found to be about 10% by weight of war;

farin. . .


Example V

In accordance" with the above‘ examples a productconij

taming-011%‘ by weight of warfarin is made spraying

10cc‘. otja,1‘0%- by volume solution of sodium warfarj

inate o’n' 99p9igra‘ms of clean, washed sand. _ About 11.83

grams‘ of this’ product added to one liter of water pro

vides a bait containing about 0.0125 mg. of warfarin

per cc. ‘


Ex'amp'le VI

In accordance‘ with the above examples a product con

taining 2.5% by ,Weight‘of warfarin is made by spraying

about 125 cc. of a 20% by volume solution of sodium

warfarinate in» 975 grams of- clean', Washed sand. About

0.95grarnslof this product added to one quart of water

provides a bait containing‘ about 0.025 mg. of warfarin

per cc.; about 1.9 grams of this product added to one

quart of water provides a bait containing about 0.050

trig-“of, warfarin per cc.; and‘ about 2.84 grams of this

product added to one quart of water provides a bait con

taining about 0.075 mg. of warfarin per cc. With, 20

50' mesh sand, compositions containing. 0.1-10.0% by

weight of warfarin are satisfactory for making up water

baits of varying concentrations although compositions

containing. 0.5-5.0% and especially 2.5% are generally

preferred.v v


‘The sand or like carrier material, in addition to the

characteristics noted above, should be of good quality and

be’ free from water soluble impurities, Clean and Washed

' Illinois standard sand sold by the vOttawa Silica Com

party and white sea sand sold by E. Sargent and Com

133ml. are illustrative examples of satisfactory sands. For -

iiropb'f' impregnation“ and coating” with the warfarinate'

the sand should be essentially free from calcareous

material as Well as clay or like materials which tend to

form ?lms‘ on the sand. Also‘, for'vdesire'd retention: of

the“vi/arfar'inatev on the sand, the sand should be dry (free

from .a'_wziteii_?ln1) at the time it is treated with the warf

sweetener ‘sateen of ‘the sand during" handling, etc.

was a

when the sand meets the speci?cations noted above. Ex

 tended tests have also demonstrated that the warfarinate

on ‘the othef hand is readily released and goes into ‘solu

tion practically instantaneously when the warfarinatel

sand composition is added to water.

The binding capacity of the sand for the warfarinate

salt is unexpected and at the lower concentrations of war

farinate on sand truly remarkable. While the phe

nomenon is not fully understood it may be due‘ in part

to electrostatic effects. This is possible due to the rel

ntively large surface of sand exposed. The binding ca

pacity may also be due in part to chemical effects re

sulting from the ionization of the sodium warfarinate in

solution. It is possible, for example, that the Na+ and

OH- ions present in the solution react with the sand

(SiOz) to form some sodium silicate situ,‘ ‘and, upon

drying, that the adhesive silicate aids in cementing the

sodiumvv Warfarinate (along with free warfarin) to the

sand. Regardless of the theory involved investigations

have shown that 20-e50 mesh sand carying up to about

10% available warfarin as the alkali metal salt are satis

factory for use in the present invention. Shaking tests

in this connection have also shown compositions con

taining. up to about 2.5% by weight of warfarin on sand

to be substantially free from ?aking, i. e., loss of war

farin salt from the surface of the sand, even when con

ducted over extended periods of time.


When it is desired to avoid the cost of transporting

large amounts of relatively heavy materials such as sand,

I have discovered that higher concentrations of the war

farinate may be initially impregnated on an intermediate

product such as diatomaceous earth or like adsorbent

material. The resulting product, shipped in the bulk,

lends itself to relatively low cost transportation charges.

However, before packaging for use by the public it is

preferably mixed with a major proportion of sand or

like‘ gritty material. The following examples will serve

for illustrative purposes.


Example VII

To 20 grams of a good grade of dry diatomaceous

?lter aid is added with stirring 20.0 cc. of a 21.8% by

weight aqueous solution of sodium warfarinate. The re

sulting mixture is then dried at about 50° C‘. for about

4'—6 hours. The resulting dry concentrate contains 19%

by weight of warfarin and is addedto sand preferably

in a ratio of about 2.51 grams of diatomaceous earth'

sodium Warfarinate to 95 grams of sand. A composi

ti‘on ‘made up of 0.251 grams of the diatomaceous earth

warfarinate product and 9.5 grams of sand when added

to a quart of water provides a bait solution containing

about 0.05 mg. of warfarin per cc.


Example VIII

This ‘example follows the .procedure'of Example VII

except that in place of the diatomaceous earth 10 grains~

of a '?lter aid such as the product known‘ as Super-Gel

is employed. The ?nal product after drying contains

about 32% by weight of warfarin and'is ready for mixing

with sand. A composition made up of 0.15lgram of,

this ?lter aid-Warfarinate product and 9.5 grams of‘ sand

when added to a quart ofwwater provides a bait solution

also‘i‘corit'aining' about 0.05 mg‘. ofrwa‘rfar‘in' p'e'r cc.- In

place of Super-Ce! other materials available on the" open

market such as‘ Celite, Dicalite and the'like and asbestos

may also be employed as‘ the intermediate product.’ In

addition, water insoluble organic adsorbents such as

puri?ed Wood cellulose available on the open market as

Polyce'l, Solka-Floc; etc. as well as'water insoluble cellu;

lose derivatives e. g. cellulose ethers such- as'Ethocel

else ‘be employed as" the‘: intermediate? prod ct.

C ‘ aoatlcaneinnguiess materiasarefprepared “I

the- procediire§ assented ~15 - matinee-v11‘ e'r‘ ' VIII.’ ‘ 1 '



7 .

Example IX 1

In accordance with the above examples, 9.5 grams of

asbestos of the woolly type is mixed with 20 cc. of about

a 20% by weight of aqueous sodium warfarinate solu

tion. After drying at 50-60“ C. the product is ready for

packaging. About 0.18 grams of the resulting dry prod

uct mixed with about 12 grams of sand or the like and

added to one quart of water provides a water bait con

taining about 0.05 mg. of warfarin per cc. The asbestos

product along with the cellulose products referred to

above may be made into ball or cockle-burr like struc~

tures into which gritty particles like sand are incor

porated by addition of a water soluble, stable gum—like

material such as methyl cellulose.


The compositions of the above examples contain only

about 0.l-l0.0% by weight of available warfarin and are

relatively safe to humans and domestic animals. The

percentages of warfarin present in the compositions

should be such that a small amount when added to water,

e. g. about 05-12 grams to a quart of water, will pro

vide a solution containing about 00125-0075 mg. and

preferably 0.05 mg. of available warfarin per cc. Com

positionsherein described are satisfactory for use in the

water bait practice and at the same time have the .

desired high safety factor.


I have also found that the warfarinate solutions may

be added to adsorbent pads‘ such as cellulose blotting

pads and that the resulting pads when added to water

release the warfarinate and form water baits of the type



desired. For example, when 0.2 cc. of a 21.8% sodium 1

warfarinate solution is added to a small piece of cellu

lose pad it provides a product containing 47.5 mg. of

warfarin. This product when added to a quart of water

also provides a satisfactory water bait containing about ‘

0.05 mg. of warfarin per cc. Gritty and like abrasive

material such as sand and the like should preferably be

incorporated in the pads to make them unpalatable to

humans. This can be readily done with adhesives such

as methyl cellulose, dextrin, etc. without affecting the V

acceptability of the ?nal bait to the rodent.


Example X


Cellulose pad ____________________________ __ 0.50

Waterglass ______________________________ __ 0.10

Sand ____________________________ _T _____ __ 0.50

Na-warfarinate __________________________ __ 10.051

Total weight _______________________ __ 1.151

1 .047 wartarln.


The washed sand (20-30 mesh) is pasted on the pads

with the sodium silicate (waterglass) in aqueous solu

tion and dried e. g. with heat lamps or warm air, etc.

The sodium warfarinate in aqueous solution is then ap- .

plied to the other side of the pads and after drying the

pads are ready for packaging. A product of this type

when added with shaking to one quart of water yields

a ?nal water bait containing about 0.05 mg. of warfarin

per cc. This combination is unique in that the sand or

like abrasive renders the product ‘unpalatable and the

sodium silicate used as the adhesive upon addition to

water raises the pH which in turn aids in keeping the

sodium warfarinate as the sodium derivative and retain- ..

ing the free warfarin in solution. This combination is

also unique in that it is not likely to be eaten because

of its unpalatability or chewed, as, for example, by a

child because of the presence of the gritty or abrasive

material. Any of the alkali metal silicates may be used

although the use of a silicate with a low NazO ratio is

generally.v preferred. ',


Natural. waters are generally around pH 7.0 and are

satisfactory for use in the preparation of the ?nal baits.

Where necessary sodium bicarbonate may be added to

raise the pH of highly acid waters.

The addition of sugars to the rodenticide composition

or bait solutions made therefrom are not recommended

but materials such as glycerine, sorbitol, mannitol, sac

charin and the sweetening agent known as Sucaryl may

be added in small amounts if desired. Salt (NaCl) up

to about 0.055% may also be added to the rodenticide

compositions or bait solutions. Suitable dyes maybe

added to color the water of the ?nal bait or the rodenticide

compositions. For example, the dye may be incor

porated in the compositions of the present invention

by addition to the warfarinate solution before applica

tion to the carrier or by addition to the carrier prior to

application of the warfarinate solution. If a dye is

used it. should be substantially odorless and tasteless

and stable at the pH ranges in the solutions in which

it is used.


The rodenticide compositions of the present inven

tion are biologically stable and have proven in practice

easy to handle and not to require the services of profes

sional licensed exterminators. The warfarin salts un

like certain poisons such as the phosphorous compounds

are also chemically stable. The action of the composi

tions in the water on the one hand are sufficiently rapid

to provide for effective kills and on the other hand suf

?ciently slow so that the o?icial tasters do not have a

chance to warn the rodent colony of impending danger.

The rodents also do not know what is taking place, i. e.,

they are subject to no pain and in many instances have

been found dead or dying at or near the bait stations.

The action of the rodenticide compositions or baits

made‘ therefrom if accidentally taken by man, domestic

animals, etc., may be readily combatted by administra

tion of vitamin K. There is no retention of the anti

coagulant in the body and no permanent damage is done.

The compositions and ?nal baits therefore have asafety

factor which‘is unique in this respect. In addition, at

the dosages employed, i. e., the relatively small per

centage of available warfarin present, the compositions

and baits made therefrom have proven relatively non

toxic to other animals when used in accordance with the

generally preferred practice in quart containers. The

preferred compositions also contain‘a large amount of

the inert gritty type carrier and are not attractive to

humans, children as well as adults, or to domestic ani

mals. In this respect they differ materially from food

baits. The compositions of the present invention thus

combine effective killing power in the rodent with a

relatively high degree of safety to the handlers and those

accidentally exposed to their action. '


While the invention has been illustrated with particu

lar reference to alkali metal warfarinate, any of the 3~

substituted 4-hydr0xycoumarin compounds referred to

above may be used in place of warfarin. However, as

pointed out above, warfarin is outstanding and it is pre

ferred to use sodium warfarinate in the novel combina—

tions described.‘


I claim:

1. A rodenticide product for use in the preparation

of water baits consisting of sand coated with sufficient

3-(a-acetonylbenzyl)-4-hydroxycoumarin sodium to pro

vide the product with about 01-10% by weight of 3-(a

acetonylbenzyl)-4-hydroxycoumarin, said coating be

ing formed by applying an aqueous solution of S-(a

acetonylbenzyl)-4-hydroxycournarin sodium free from

free alkali to dry, clean, washed sand and drying the

same thereon, said coating being characterized by‘be

ing ?rmly bound to the sand when dry and being readily

released in solution when contacted with water.


2. The composition of claim 1 where the sand i520»

50 mesh and the composition contains 05-50%. by

weight of available 3-(a-acetonylbenzyl)-4-hydroxy



3. The composition of claim 1 where'the sand is

about 20~30 mesh and the composition contains about




2.5% by weight of available 3-(a'Ecet0ny1benzyD-4


References Cited in the ?le of this patent



1,270,630 Leist ______________ __ June 25, 1918

1,450,128 Baker ______________ __ Mar. 27, 1923

1,572,568 Smith ________________ __ Feb. 9, 1926

2,427,578 Stahmann __________ __ Sept. 16, 1947 10





“Raticidal Potentialities of Wad-42,” by D. Glenn

Crabtree, February 1950, in Soap and Sanitary Chem



“Controlling Rats and Mice with Warfarin,” Publica

tion of October 1950, Prenticess Drug and Chemical

Co., Inc., 110 William St., N. Y.


Senaste kommentarer

28.01 | 18:32

Hej, Tina, sex år har gått sedan min mors död. Men fortfarande utgör det sättet på vilket hon dog en fasansfull mardröm för mig, och kommer att förbli så.

12.01 | 11:45

Herregud när man läser detta, så hemskt!

03.05 | 14:02
Waran=Råttgift dödar har mottagit 3
27.04 | 15:27
Nobeldagen-vetenskap har mottagit 1
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