Note: Descriptions are shown in the official language in which they were submitted.
rl~h:is iS a d:iv.isioll ol~ copendincJ applicatior
390,~15, filed November 19, 1981.
This invention relates to intermediates ~or the
preparation of 0-alkyl and 0--aryl S-(tertiary al~.yl~
alkylphosphonothioate compounds which possess insecticidai
and nernatoci~al properties,
Certain alkylphosphonothioate insecticides are
de-scribed in the prior art, for example5 in U,S, Patent
No, 39209S020, However, none of the species described in
that patent or in other known prior art possess a t~rtiary
alXyl ~roup attached to the sulp}~ur atom,
It has now been found that certain S-tertiary
al'kyl compounds possess particularly useful insecticidal
or nematoci.dal ackivity,
In our Application No, 390415 (from which this
application is divided), we have described and claim~d
compounds of the ~eneral -Eo~nula:-
11 / ~1
R - P (I)
\ SR2
wherein R represents alkyl of 1 to 8 carbon atom~s 9 haloalkyl
of 1 to 8 carbon atom~s, alkenyl of 2 to 8 carbon atoms, halo-
al]senyl oE 2 to 8 carbon atoms, alkynyl of 2 to 8 carbon
atomsS or haloalkynyl of 2 to 8 carbon atoms,
f~
2 --
Rl represents alkyl of 1 to 8 carbon atoms or aryl and
R2 represents tertiary alkyl of 4 to 8 carbon atoms, which
exhibit a wide range of insecticidal and nematocidal
activity and are of particular interes-t in controlling
corn rootworm (Diabrotica sp) because of their excellent
activity against this pest and their long residual soil
activity.
It is to be understood that, in this specification
and the accompanying claims, unless otherwise indicated,
alkyl groups and moieties may be straight- or branched-chain.
In general fonnula I:
R preferably represents alkyl of 1 to 4 carbon
atoms, especially methyl or ethyl;
Rl preferably represents alkyl of 1 to L; carbon
atoms (compounds in which Rl represents phenyl or phenyl
substituted by one or more (preferably one) atoms or
radicals selected from the group consisting of alkyl of
1 to 4 carbon atoms (preferably methyl), alkoxy of 1 to
4 carbon atoms (preferably methoxy), alkylthio of 1 to
4 carbon atoms, alkylsulphinyl of 1 to 4 carbon atoms,
alkylsulphonyl of 1 to 4 carbon atoms, chlorine, bromine,
fluorine, nitro, cyano and trifluoromethyl, are also
preferred); and
R2 preferably represents tert-butyl or tert-amyl.
~5 Particularly preferred compounds of general
formula I are those in which R represents methyl or ethyl,
R~ represents alkyl of 1 to 4 carbon atom~ and R2 represents
t-butyl or t-~nyl Other particularly preferred cor~ounds
are those :in w~ich R repre~ents methyl or ethyl, R~
represents phenyl or phenyl ~ubstituted ~y a chlorine or
fluorine atom, or by a methyl~ methoxy or trifluoromethyl
~roup and R~ represents t-butyl or t-amyl
The compounds of general formula I can b~ prepared
by the application of known methods By the expression
"known methods" as used in this specification is meant
methods heretofore used or described in the literature
The present invention provides S-alkyl alkylphos-
phonothioic halides of the general formula:
O X
11/
R - P
\ (II)
SR2
wherein R and R2 are as hereinbefore defined and X
represents a halogen atom, preferably chlorine, which are
useful as intermediat~sfor the preparation of compounds of
general formula I~
The compounds of general formula I are prepared
by the process which comprises reacting an S-alkyl
alkylphosphonothioic halide of general formula II, wherein
R, R2 and X are as hereinbefore defined, with an alcohol
or phenol of the general formula RlOH~ wherein Rl is as
5~L
hereinbefore defi.ned, in the presence o~ a base,
l~e process proceeds ln accordance with the
reaction scheme:
~ORl
R - P + RlOH b~ R - P + base , HX
SR2
SR~
wherein~jRl~ R2 and X are as hereinbefore defined,
The reaction is advantageously carried out at a
temperature of about 0 C to 100 C in an organic solvent
in the presence of a tertiary amine, or an alkali metal
salt of the alcohol or the phenol RlOH~ prepared from
the alcohol or phenol and an alkali metal such as sodium,
Suitable organic solvents are, for example~
benzene, toluene, cyclohexane and 2-butanone, or an
alcohol RlOH,
Suitable tertiary amines include trimethylamine,
triethylamine, dimethylaniline, diethyl.aniline and pyridine,
The synthesis of S-alkyl alkylphosphonothioic
halides is usually accomplished by methods other than the
direct addition of thiols to alkylphosphonic dihalides
because direct reaction is normally accompanied by an
undesirable side reaction in which both halogen atoms in
the phosphonic dihalide are substituted by an alkyl thiol~
The side reaction is a particular problem when normal
alkyl thiols are used, Thus, when the synthesis of normal
S-alkyl alkylphosphonothioic chlorides is desired,
alternative routes are selected,
It has been discovered that tertiary alkylthiols
react smoothly with alkylphosphonic dihalides to gi.ve mGno
addi-tion of one thiol in good yield, according to the
following equation:
O X solvent 1l /X
5 RP + HSR2 ~ base ~ RP + base.HX
X \ SR2
III
wherein R, R2 and X are as hereinbefore defined . According
to a feature of the present invention, the cornpounds of
general formula II are prepared by reacting a compound of
the general formula III wherein R and X are as hereinbefore
defined with a compound of the ger-eral forrnula R2SH wherein
R2 is as hereinbeiore defined in a solvent, in che pxesence
of a base at a temperature of about 20C to 100C. In
the compounds of general formula II, preferably R represents
alkyl of 1 to 4 carbon atoms particularly methyl or ethyl
preferably R2 represents tert-butyl or tert-amyl, and
preferably X represents chlorine.
Suitably the reaction is carried out in an organic
solvent, in the presence of a tertiary amine such as
trimethylamine -triethylamine pyridine dimethylaniline
or diethylaniline.
3~ ~
-- 6 --
Suitable organic soJ.vents, w~lich are preferred,
include benzene, -toluene, cyclohexane, acetone and
2-butanone .
Generally, the reaction i s conducted at a
5 temperature of al~out 20C to 100C, but the temperature
is not critical except insofar as it is sufficient to make
the reaction proceed at a reasonable rate and is not
excessive. It has been found advan-tageous to add the
tertiary amine to the other reactants at a ternperature
10 of about 20C to 30C and then to heat the entire reaction
mixture to a temperature of about 70C to 80C to complete
the reac tion.
I'he reac tion is normally carried out wi.th an
approxirnately equal rnolar ra tio of the alkyl phosphonic
15 diha] ide, thiol and the base. An excess of about 10 to
20% of the alkylphosphonic dihalide can be used relative
to the other reactants. However, the use of a slight
excess of the thiol and the base rela-tive -to the
alkylphosphonic dihalide ( 5-10% excess ) did not appreciably
20 affec-t the yieldn
Particularly pref erred compounds of general
forrnula II are S-tert-butyl ethylphosphonothioic chloride,
S-tert-arnyl ethylphosphonothioic chloride, S-tert-butyl
methylphosphono',hioic chloride, arld S-tert-amyl methyl-
25 phosphonothioic chloride which are used as interrnediatesin the following Examples 1 to 16~
I`he following Examples illustrate the
preparation of compounds of general formulae I and II and
the pesticidal properties of the former.
EXAMPL~ 1
S-tert-Butyl ethylphosphonothioic c_loride
0 Cl
11/
CH CH ~ P CIH3
s f CH
CH3
To a solution of ethylphosphonic dichloride (32.0 g,
0.22 mol) in 300 ml toluene, was added 2-methyl 2-
propanethiol (18 g, 0.2 mol). While stirring,-trie-thyl-
amine (22 g, 0.22 mol) was added dropwise, -the temperature
of the reaction mixture was maintained at 30-35C during
the addi-tion of the amine. After addition of the amine
the mixture was stirred overnight at room tempera-ture.
~le amine hydrochloride which precipitated was filtered
off and the toluene solution was concentrated under vacuum,
Hexane (200 ml) was added and the solution obtained was
filtered.
m e solvents were stripped off under vacuum
and the residual liquid was distilled. The product (25 g,
72.5% yield) distilled at 72-73C/0.7 mmHg. Proton
magnetic resonance spectroscopy in deuterochloroform
(CDC13~ with Si(Me)~ as reference confirmed the structure
.- ~
of the title compound.
EXAMPLE 2
Pre arat:ion of 0-eth l-S-tert-butyl. ethylphosphonothioate
P _ Y
To a solution of S tert butyl ethylphosphonothioic
chloride (obtained as described in Example 1) (8.0 g,
0.048 mol) i.n toluene (50 ml) was added a solution of sodium
ethoxide (0Oo4 mol) in ethanol (40 ml). The addition was
carried out dropwise, with stirring under a nitrogen
atmosphere. Stirring was continued overnight at room
temperature, and then approximately 80% of the solvents were
removed under vacuum. Toluene (100 ml) was added and the
sodium chloride formed from the reaction was fil-tered off.
Toluene was stripped off under vacuum and the residual
li~uid was distilled. The product (5.8 g, 69.6% yield)
distilled at 69-72C/0.2 mm~Ig.
Analysis of the proton magnetic :resonance spectrum
of this product confirmed the structure of the title
compound.
EXAMPLE 3 to 6
In a manner analogous to that of Example 2, the
following compounds were prepared.
1 / ORl
R - P
SR~
9 _
Ex~e~ R Rl R2 B. ~ .
C2 5 CH3 t-butyl 64-67/0.7
4 C2H5 C3H7 t-butyl 61-63/0.05
2 5 (CH3)2CH t-butyl 42-43/0.05
6 C2H5 C2H5 t-amyl 56-58/0.07
EXAMPLE 7
Preparation of O-phenyl-S-tert-butyl ethylphosphonothioate
O /=\
Il /~
C H -P CIH3
S - C ~ CH3
~H3
To a solution of S-tert-butyl ethylphosphonothioic
chloride (5 g, 0.025 mol), and phenol (2=35 g, 0.025 mol)
in acetone (20 ml), was added, in one portion, triethylamine
(2.5 g, 0.025 mol), the mixture was stirred overnight under
nitrogen at room temperature. ~he reaction mixture was then
diluted with toluene (100 ml) and washed once with 5% w/v
sodium hydroxide solution, and twice with water. The
solution was dried over anhydrous sodium sulphate and the
solvent was stripped off under vacuum. The residual liquid
- 10 --
was subjected to high vacuum (0~2 mmIIy) at 60C for
15 minutes to yield the desired product as confirmed
by its pro-ton magnetic resonance spectrum in deutero-
chloroform (CDC13) with Si(Me)L~ as reference.
EXAMPLES 8 to 15
In a manner analogous to that of Example 7,
the following compounds were prepared
O ORl
R - P \
SR2
Example _ Rl R2
2 5 o-methyl-phenyl .ert-butyl
C2H5 p-chloro-phenyl -ert-butyl
C2H5 phenyl tert~amyl
11 C2H5 m-trifluoromethyl- --ert-amyl
phenyl
12 C2H5 p-fluoro-phenyl tert-amyl
13 C2H5 p-chloro-phenyl tert-amyl
14 C2H5 o-chloro-phenyl tert amyl
CH3 phenyl tert-amyl
XAMPLE 16
Meta-cresol (4 6 g) was dissolved in acetone
(100 ml~ and potassium carbonate was added The mixture
was stirred at room temperature for 30 minutes, and
S--tert-butyl methylphosphonothio:ic chloxide (7,5 g)
was then added,
Stirring was continued overn.ight, and the
solution was then filtered and the solvent evaporated,
Water (100 ml) was added and the mixture extracted with
diethyl ether (100 ml), The ethereal extract was washed
once with 5% w/v potassium hydroxide solution, then with
water and was finally dried and evaporated to give 4,0 g
of 0-3-tolyl-S-tert-butyl methylphosphonothioate,
The product was identified by its proton magnetic
- resonance spectrum, Its purity is higher than 90/O,
Examples illustrating the pesticidal. properties
of compounds of general formula I are included in our
Application No, 390415, in that application we have
also described insecticidal or nematocidal compositions
contai.ning the compounds of general formula I and use of
the compounds of general formula I in a method ~or the
contro] of insects in crops~
