CA1147729A - Formamidine and guanidine derivatives as herbicides - Google Patents

Abstract

A B S T R A C T
The present invention relates to formamidine sulphided or disulphided and thiocarbamoyl-guanidines endowed with herbicide activity. The thiocarbamoyl-quanidines are prepared from formamidine sulphides or disulphides.
The process for their preparation, and their use as herbi-cides are disclosed too. The herbicides compounds of the present invention are particularly useful against monocoty-ledona, dicotyledons and against infesting weeds.

Description

This present invention relates to new herbi-cide compounds and, more particularly, to new formamidine . sulphides and disulphides 114'7729

- 2 and to thiocarbamoyl guanidines endowed with a high herbicide activity, to the use and the method of preparing same.
A restricted number of formamidine disulphides is known in literature, however herbicide properties were never recognlzed to such com~ounds.
P,K. Srivastrava et al. prepared, for merely academical purpo-ses, the following formamidine disulphides in the form of hromo hydrates: -N N . 2HBr~P~K. Srivastrava et al., C \ / C \ Tetrahedron Letters 23, NH S-S NH 2725, 196B) C 11 -C13 / C~2-C6~
N N. 211Br (P.K. Srlvsstrava et al., C / C \J. Ind. Chem. Soc. 40, ~2N S-S N1~2 803, 1963) 1~47729 N N . 2HBr (P ~ . Srivastrava et al., Il . .
/ C \ / C \ Indian J. Chem. 1, 354, HN S-S NH 432, 1963) However no analytical data for the characterization of the abovesaid three compounds are reported, probably because, due to their instabillty, they cannot be isolated as free bases.
Similarly, from the technical literature only a limited number of derivatives belonging to the class of thiocarbamyl-guanadi-nes are known. To this class of compounds too, had never been previously recognized herbicide properties.
lleld, Gross and Schubert / Zeitschrlft der Chemle 13, 341 (1973),~
by oxidation of the N,N-dimethyl-N'-phenyl-thiourea wlth thlo-nyl chloride, prepare N ,N -dlmethyl-~ ,N dlphenyl-~ -~N,N-dl-methyl-thiocarbamoyl/-guanadine of the formula:

N
/C\ /C6~35

3 I N
CH3 S=C N(C13)2 ~1~7729 Srivastrava et al. /J. Ind. Chem. Soc. 40, 803 (1963)/ prepar-ed derivatives of thiocarbamoyl-guanadine non substituted on the nitrogen atom in position 1 and on the nitrogen atom of the thlocarbamoyllc group in the form of bromohydrates.
We have now found, and this forms an object of the present invention, formamidine sulphides and disulphides of general formula I and thiocarbamoyl guanidines of general formula II:
R R R \
N N . N
Il 11 11 R - N / ~S) N - R R - N N - C - N - R
n l2 R2 1 11 !2 (I) ~II) In both formulae I and II:
R - phenyl optionally substituted by one or more halogen atom~, one or more al~yl or haloalkyl groups having from 1 to 3 carbon atoms7 R and R ~like or unlike each other) = alkyl C1-C3, alkoxvl C -C
or R and R to~ether are the group -CH2- (CH2)3- CH2 or tle grOUP - Cll2 - C112 - O - Cll2 2 ~ ~ . . .
,' ~
.

~147729 n = 1 or 2;
provided that when in formula II Rl = R = CH3, R be a substituted phenyl.
Compounds of formulae I and II, even in the case in which in formula II R = R = CH3 when R =
unsubstituted phenyl, are endowed with herbicide activity against both monocotyledons and dicotyledons and can be usefully utilized, as such or in form of suitable compo-sition, in the fight against infesting weeds, the method for fighting infesting weeds by using compounds of formulae I and II and compositions thereof being a second object of the present invention.
The preparation of the compounds of formulae I
and II, which forms a further object of this invention, is achieved according to the processes herebelow des-cribed.
The compounds of general formula I are prepared by oxidation of trisubstituted thioureas (III) in the presence of an organic base (reaction 1), so obtaining the compounds of formula I in which n = 2 (disulphides), from which, by desulphurization in the presence of triphenylphosphine (reaction 2), the corresponding sulphides are obtained. The same compounds ~mono-sulphides) can be obtained also by reacting a trisubsti- --tuted thiourea (III) with the proper imidoyl-chloride (IV) in the presence of a halogenhydric acid accepting base (reaction 3) S Rl R R
Il / \ / (I,n=2) 1) R - N~ -C - N oxidants~ C

S--S
Rl_N N_Rl 1 12 ,-~ - 5 -2) (I, n=2) + (C6H5) 3P (I, n=l) + (C6~I5) 3P=S

Cl Rl 53) (III) + R - N = C - N (IV) base ~ (I, n=l) Reaction 1 is conducted by oxidizing thiourea (II) in the presence of an organic base and in an inert solvent.
As oxidizing agent it is possible to use, for example, a halogen such as bromine and iodine (Br2, I2), while a tertiary amine such as triethyl- or tributyl-amine can be used as an organic base.
Excellent yields were obtained by employing methylene chloride (CH2C12) or chloroform (CHC13) as a solvent.
Under the conditions described hereinbefore the reaction occurs at room temperature and in very short times. At the conclusion of the reaction the mixture is washed with water and anhydrified, and the solvent is evaporated. The resulting product can be utilized as such, otherwise it can be crystal-lized from non-polar solvents.
Reaction 2 can be advantageously conducted by reacting equimolar amounts of disulphide (obtained from reaction 1) and triphenyl-phosphine, in diethylether at about 0C.
The resulting triphenyl-phosphine sulphide precipitates and is removed by filtration at the end of the reaction. The reaction mixture is treated according to usual laboratory techniques and the formamidine - ' 114772~

sulphide so obtained is purified by crystallization from hydrocarbons.
Reaction 3 directly leads to the obtainment of formamidine sulphides without preparing first the corresponding disulphides.
The reaction is conducted in an aprotic solvent and in the presence of a halogenhydric acid-accepting base.
An advantageous process for conducting the abovesaid reaction consists in adding a solution of the thiourea derivative ~II) and of a slight excess of base (tertiary amine) in methylene chloride, to a solution of imidoyl-chloride ~III) in the same solvent.
The mixture is stirred at room temperature and the reaction occurs in a short time.
The product is then isolated according to the usual laboratory technique.s.
The preparation of the compounds of General Formula II is achieved by reacting a formamidine sulphide or disulphide (I) with a catalytic amount of a strong anhydrous acid (reaction 4) R R
~ /
N N
Il 11 1 / ~ / N - Rl (I) H > (II) 1~47729 Reaction 4 is preferably achieved by adding a catalytic amount of an acid ha~ing a sufficient force to salify the basic groups of the sulphide or disulphide of Formula I, to a solution of this latter in an aprotic polar solvent such as for instance 11~7729 chloroform (CHCl3).
~s a strong acid there may be used an anhydrous halogenhydric acid or a trihaloacetic acid.
The reaction rate depends, besides on the nature of the for-mula I compound that is made to react, also on the amount of acid used.
~or amounts of acid equal to 0.1 e~uivalents per mol of com-pound of formula I, reaction 4 is complete also at room tempe-rature within a few minutes.
Once the reaction has taken place, the chloroformic solutlon is washed with a saturated aqueous solution of sodium bicar-bonate ~NaHCO3) and is then anhydrified. The solvent is then evaporated under vacuum, thereby obtainin~ as a residue the corresponding compound of formula II which may thereu~on be puri~ied by crystallization.
The process for the prcparation of the compound.s of qeneral formulae I and II can be sumarizcd a3 rcpor~cd in tlle ~ollow-inq scheme 1 ~+

U~ _ :C ..
,, ~o ,, U ~
H
~ . /~

. ~; ~
O \/
_I ~
~ ~, U--U

_ :~ _ I ~ +
a~ v~
a S Z
O
~1) - ' ' .. . .

.

-11~7729 The compounds of formulae I and II reported in the following Table 1, have been prepared according to the processes here-above described.

~, .

r. ~ ~

~47729 ~ d d ~ . ~

~'I b ~ ~. .

N _ Z N

Z_ t~ _ .

H ~r \Z~_N~ ,0 u~ g~ (t) O ~ t' O
~1 ~ >~ r~ C ~ 7 u~ ~ ~
, . I .. _ C 0 O O O O d 1~ ~ ~ O
~1 ___ O I Z ~ I Z

Z _ ~ ~ ._ I zN

N
C~ ~ Y~ Y '' O O _ - -~ ,.` - ' ' ' ' ~

r ~ ~ O

. O
~ 'oo . . . .. .
~ O~ O 0 O

â
. _ ~.~ .. __ _ U) 10 O ~t ~ N ~D . t` 0 ~
7 ~ ~ u~ . ~ ~ o u 0 u~ ~ ~

~ . .. .
C . 0~ t` UJ O g U) ~ ~ ~0 C~l ~ 0 ~ ~ ~ U ~ - ~ ~ ~ ~ ~ ~ o I~ . ~ I z ~ I Z ~ I Z L) I Z
. __ ~ ~ ~ ~ ~ 1~ ' ~ :~ ~ ~
~ S) I L.) T

--_ 1 1 ~ S S
H F ~ ~ ~_ ~J o~ ~ u~ ~o ~
O .) .~ ._ _.
~ ~ E _ _ _ _ .- U 11 _ _ __ , .. _ ._ ~ : -.
., .

2~
Z Z N N N

_1~ , . __ O
~ ~ ~ ~ . O ~ 0 N ~ 0 O

~ , ~ _ -X
_ C ~ ~ ~ . ~ 1~ ~ ~ ~O 0~ ~ , C ~ 1~1 L~ ~ 'J') ~ It~
_ _.
C . U1 ~ ~ ~ 0 0 O ~ ~ ~ ~ ~
G~ O ~D ~ C Z ~n Z ~ T Z (_) I Z

N O N ~ r O ,.
Z O Y ~ ,_ . ._ . - , _ q ~' Y

H _ _ N _ _ _ _ O o- 0 a~ ,o' .
._ , ~ " .

, 11~'7'~9 N N _ ~t ~t

4~ 3 U~ ~t a ~t 'n u~ ~Nt co ~t CO ~t Nn S ~ ZCC~ u7Z~ ~ ZN ZCC~ n Zcc~ ~
~ I ~t ID R N I ~ CC ~t ~- æ æ ~OD
F~ ~n ~ ~n ~
cr ~ ~ ~ n ~ CLl __ _ _ _ U~ _ N ~ l n r~ CD n ~, _ _ E
-- N
~ ~_ _ ._ Ct`o C~ ~i C ~ ~ I" LCO~ ~t ~g un~ CD a~
C ~ ~S~ u~ a ", u; cn ~ rr, a et ~ co ~t O

C ~ N ~ CO r- COCO Ir) CO '?, U ~ N In a. O
E O ~ ~ U~ ~ ,o ~D , ~unt ~ a- et ~ ~t ~
,~ S ~0 L~ I Z L~ T Z L~ C Z L7 I Z L) T z LY N I " ~ ~`J I O
_ _ . 1~ _ _ .

Cr~.I N 3:
: ~ ~ ~ n n 1~ Ll ~ ~t ~t V ~ ~0 )~ _ ~--1 ~ . ~ N N
a.) ~. .

[ ~ ~ ? N ~ U~ ~D

O E _ _ _ _ O 1. _ _ ._.__ ,., " ~ . , : ' '.~

~1~'7t729 r - ~ ~ ~ ~ ~ ~ ~L-D ~ zm m Z~D r~
L T O I ~) 0 N 0~ I ~ 11~ I 0 .~ ~
_ ~ 0 0 0 ~ ô 0 ~ O ~ _~O ~ æ Y~

~c' I 1 , ~o ~ ,~

i I _ I

_ C ~O N
1~

~ c ~ 01 0 1~1 ~ N 5~3 U~ r- tO ~ ~ N 1~ 0 ~ .t) ~O (-- &~ ~ o 0 .-- ~I ~ O _ ,.

.~ ~ N ~0 1') ~ <O N a- 07 1~) 1~ t`
r o ~ ~o ~o 1 53 ~o 0 ~ ~ a~ o m z ~K ~0 t~ ~ :C~ l Tr' ~ cm ~ I m ~ r~ m H N N . . _ 'D __ .. _ to ~ ~0 ~ 0 O. æ N ~I
~ _ ____ _ ___ _ _ O ~ .___ _ _ _ ,,~ ., .,: . . .

, I l .

O O ~N

~'/ O U r~l N ~ ~ ~ .
_ ~ ~ æ _ _ . ~ 2 æ
~ O 'O 0~

~ ~ ~ ---- N ~ ~

3~o o~
e o N -N _ 1 ~.) ~ ~ __ _~N _ _ 1 H ___ _ O O O 1~) . _ N

'0J _ ___ _ L

1~477~9 .. ._ L ~ ~r) ~ N cn r Q a)Z N N ~ I ~ ~ ~t . _ - .~ ____ ,~ ~ 0~
__ __ _ ____ N ~ ~J N N ~-~
. ~L~' ~ _ E ~ ~0 01 ..

r~ N N
.__ ._ X ~ ~J ~ N I~J Y;~ O 0 J ~t ~~g (D r- ~ ~ D

,, ~e .___ ... ___ ~ S <D ~ ~ ~ ~ ~ æ ~ ,~

. N _ . I Z ~ I Z

_ _ .. . _._. T y N

~1 ~r, I N L~ N~
r L) T
. I _ Y I D L~
Q:L7 ~ 'O _ .__ ~ 1 O N N N N
~) -~-o ~ - =----= =

1~7 ~9 .

E . L17 ~ O ~D O rJ ~ ~ ~n ~
L7- L~ L\l Ltl Z~ r~ Z L~ ~O ~D
_'r ~_ _ __ l"_ _ _- __ ___ _.

L~ 'n (n ~ ~1l ~ .-l _ ~^~
. ~

._ ~L7~ L~ LD ~ L'J D LJI 0 N L,o 1;~ ~ LD t--o ~ ~ ~ ~ o In ~ ~ o. o LD

ru _ n ~ 0 ~D ~ ~ N "7 0 N 3 N 0 L''l ~u n n n ~ io Ln ~ ,n m , o gl LD
LLI ~ L~ ~ Z L~ I Z ,~ T Z ~ T Z Z 1~ rJ7 '~ ~ ~ _ IL~7 , ~L~I Y

~-- L_J 1 L 7 L~ ~ ~ C N T
_ ~1 Cr: ~D LD Y LD Y rD

C~

~ g Z L~') "~ N~ "~ ~S r~
O ~

:. :

11477'~9 - ~n -~ . " . I

".~- _ ,,~, _ _ N . N m b _ _ P:
. D ~. _ __ _ ._ ~ G G O G~

r3 r U) t`- n ~ N d' r~

_ _ ~JI ~ o N 0 0 0 .
F: L U) J ~ O ~i 'J O
IIJ ~ _ ~) :CZ ~ Z

L~:~ N ~N 1~ N

~ --~ ~N
_l~- o ~/ ~-- ~n t~o n ~

,..

~4~7'~9 The compounds of general formulae I and II are endowed with a high herbicide activity exerted against both monocotyledons and dicotyledons.
The data relating to the activity of some representative compounds, obtained as described in example 5, are reported in the following Table 2.
The herbicide activity was tested on the following weeds:

Monocotyledons A = Echinochloa crusgalli B = Avena fatua C = Lolium italicum D = Sorghum spp.
E = Setaria glauca F = Digitaria sanguinalis G = Alopecurus myosuroides H = Panicum dichotomiflorum I = Festuca pratense J = Bromus sterilis K = Poa annua Dicotyledons L = Stellaria media M = Ipomea purpurea N = Vigna sinenbis O = Rumex acetosella P = Galinsoga parviflora Q = Convolvolus sepium R = Convolvolus ariensis S = Geranium dissect T = Sida spinosa U = Brassica V = Gypsophila muralis W = Galium aparine.

The data relating to the herbicide activity reported in Table 2 are expressed using a scale of values from O (no herbicide activity, growth of the plant like that of the check) to 4 (death of the plant or complete stop of growth).

1 ~

- 23 - 1147~Z9 .- ... ~ .. ~__ ~ ~ ~ r ~ ~ ~r ~r ~:r ~:r ~ ~r ~ ~r ~r ~r ~ ~r ~r ~r 1 ~ ~r OP~ ~r ~ ~r O' ~er er ~ ~ q~ ~er ~
Z ~r ~ ~ ~ ~ ~ ~r ~r ~: ~r ~ ~:r ~ ~ ~ ~ ~ ~:r ~ ~r ~r ~r ~ er er ~r er ~r ~r ~ ~r _ _ . _ ,_ ._ _ _ _ ~ ~:r ~r ~r ~r ~ ~r ~r ~r ~ ~r~
C 5: ~ ~r ~r er ~r ~r~r ~5 ~ ~ ~ ~ ~ ~r ~r ~ ~ ~ ~ ~er 0~ ~r~r ~ er ~ ~ ~r er .:r ~ ~r t~ r ~ ~ ~ ~
~ ~ ~r q~ ~;r ~ ~ ~:r ~
. _ , ~

Q) .C D ~ C`l D D ~D D ~ ~D D ~) N
a x ___ ___ ~ ~ Q) a) ~ ~ c) qJ
a)u~ 3 ~3 3 3 3 ~ ~3 C ~- ~ t~' tJ~ ~ ~ h a) ~ t7~ ~
v F, E , v F V F F , v E~ ~/ O O a) O o o o Q) o ~ O
,_,__, __. I __ P. 1- __ ~ __ l -æ
~ u~ ~c o ~o .n FO~'~ I

11477'~9 Depending on the particular compound, the best effectiveness of the herbicide activity is achieved by application in pre-emergence or in post-emergence, that is when the infesting weeds have not yet emerged out of soil or when they have.
The herbicide compounds of the invention prove also to be selective with respect to usefull cultivations such as wheat, maize, soja and cotton.
For agricultural applications the active com-pounds are distributed on the soil as such or~ preferably, in form of suitable compositions consisting of one or more of the compounds of formula I as active principle and one or more suitable carriers. Suitable compositions include wettable powders, liquid pastes, granular formulates and so on.
Suitable carriers include, depending on the type of composition, silica, kaolin, diatomaceous earths, bentonite, pomix, organic solvents, water and so on.
In the composition may be included also addi-tives such surfactants, emulsifiers, thickners and so on.
A list of carriérs and additives is reported on " Mc Cutcheons-Detergent and Emulsifiers-~orth American and International Editlons, 1977 Annual. Mc.Cutcheons Publ. Co., Glen Rock, New Jersey (U.S.A.)".
The preparation of said compositions is carried out according to procedures common to the formulative praxis.
If desired in the compositions may be included also other active ingredients such as fertilizers, insecticides or fungicides. The amount of active principle (Compounds of formulae I and II) to ~e distributed on the soil depends on various factors such the enviro~lent~ conditions, the kind of ag~icultural cultivation ~1 to be protected from infesting weeds, the type of composi-tion and the particular active principle.
Generally, amounts of compounds of formula I
and II comprised between 1 and 6 kg/ha are suitable for obtaining good results in the fight against lnfesting weeds, the preferred amount being of about 2-3 kg/ha.
The following examples are given to better illustrate the present invention.

Preparation of Nl, Nl-dimethyl-N2-phenyl-formami-dine disulphide (Compound n 18, Table 1). ~Reaction 1).
., 11477A~9 A chloroform solution of lodine (5.2 g ln 100 ml) was added dropwise and under stlrrin~ to a solution of N,N-dimethyl--N'-phenyl-thiourea (5 g, 0.0277 moles) and triethylamine (7.5 ml) ln chloroform (50 ml).
The addltion was continued until the lodine colour remained persistent in the reaction mixture.
After 15 mlnutes the stirring was stopped and the reaction mlxture repeatedly washed wlth water (750 ml) and anhy-drlfied with anhydrous ~a2SO4. After removal of the solvent a yellow oll was obtalned whlch, crystallized from n.hexane, provlded 4 g of the product to be obtained.

Preparatlon of N ,N -dlmethyl-N -phenyl-formamide sulphide (Compound No. 17, Table I). (Reactlon 2).
A solution of N ,N -dlmethyl-N -phenyl-formamldlne dlsulphide pre~arcd as dcscrlbed ln Examplc 1 (350 m~) ln diethylcthcr (2 ml) was additioned, under stirring, wlth 256 m~ of triphe-nyl-phosphine, while outside cool1n~ by means of a water and lce bath.
After conclusion of the reaction ~about 3 hours), the white preclpitate of triphenyl-phosphine sulphidc was removed by filtratlon at 0C.

1~47729 The solvent was then removed under vacuum and the residue, crystallized from n.hexane, provided 112 mg of the desired product free from impuritles.

EX~MrLE 3 Preparation of N ,N -dimethyl-N -phenyl-formamide sul~hide ~compound No. 17, Table I). (Reaction 3~.
A solution of N,N-dimethyl-N'-~henyl-thiourea (0.9 g) and ~hos~en ~COCl2~ ~2 g), in methylene chloride, was stirred for 8 hours at room temperature. After removal of the solvent under vacuum, the residue ~imidoyl chloride) was dissolved ln a solutlon of triethyl-amine(0.7 ml) and anhydrous methy-lene chloride ~20 ml).
A solution of N,N-dimethyl-N'-phenyl-thiourea ~0.9 g) and triethyl-amine ~0.7 ml) in methylene chloride ~20 ml) was added dro~wlse, under stirring and at room temperature to the above mentloned solutlon.
Aftcr an ei~ht-hour stirring thc reaction mixture was wash-ed wlth the water, anhydrified with anhydrou~ sodium sulphate, and the solvent was removed under vacuum. The res~due was crystallized from petroleum ether, so obtainlng 1.4 g of the desired product (yield = 86~).

~ 47729 Preparation of N ,N -dimethyl-N ,N -diphenyl-N -/(N,N-dlme-thyl) thlocarbamoyl/ guanidine (Compound n. 27, Table I) (Reactlon 4).
43 ~l of trifluoroacetlc acid were additioned to a solution of N ,N -dimethyl-N -phenyl-formamid~ne-dlsulphide (2 g, S,58 mols) obtalned as descrlbed ln Example 1 in chloroform ~200 ml).
The reaction mlxture was then allowed to rest for 15 min.
at room temperature, after which lt was washed wlth a satura-ed ~olutlon of NaHCO3, and anhydrlfled wlth anhydrou~ Na2SO4.
After removal of the ~olvent by evaporatlon under vacuum, the re~idue was crystalllzed from n.hexane/benzene (70:30).
1.3 g of the deslred product were obtained ~yleld 71%).

Determinatlon of the herblclde actlvlty.
Some pot~ were prepared (upper dlameter ~ 10 cm, helght = 10 cm) whlch contalned sandy oll, and each pot was ~owed with one of the lnfestlng weeds llsted on pages 21 and 22. To each pot water was added ln the amount necessary to a good sproutln~ of the ~eed~.

. ... ..

The pots were divided into three sets.
The first one was not treated with any herbicide and was used as a check.
The second set was treated) one day after sowing, with a hydroacetonic dispersion (20% by vol./vol.) of the compounds of the invention, in order to determine the herbicide activity in the pre-emergence stage.
I'he third set was treated, 15 days after sowing (namely when the little plants had already reached a height of 5-10 cm, depending on the species) with a hydroacetonic dispersion (20~ by vol./vol.) of the compounds of this invention in order to determine the herbicide activity in the post-emergence stage.
All the pots were kept under observation in a conditioned chamber at temperatures ranging from 15 to 24C, relative humidity = 70~, photoperiod = 12 hours, light intensity = 2500 lux.
Every second day all the pots were uniformly watered in order to secure a humidity degree sufficient for a good growth of the plants.
28 days after the treatment, controls were carried out to ascertain the vegetative stage of the plants, the results thereof being expressed according to the scale of values from 0 (growth equal to the one of the check) to 4 (full stop of the growth or complete killing of the plants).

9 _

Claims (10)

The embodiments of the invention in which an exclusive property or privilege is claimed are defined as follows :

1. Method for fighting infestations of mono-cotyledons and dicotyledons both in pre-emergence or in post-emergence, characterized in that on the soil there are spread, either as such or in suitable compositions, in an amount of from 1 to 6 kg/ha, one or more of the herbicide compounds covered by the general formulae:

(I) (II) wherein:
n = 1 or 2;
R = phenyl or phenyl substituted by one or more halogen atoms, one or more alkyl or halo-alkyl groups, having from 1 to 3 carbon atoms;
R1 and R2 (equal or different from each other) = alkyl C1 - C3, alkoxyl C1- C3 or R1 and R2 together are the group -CH2- (CH2)3- CH2- or the group -CH2 - CH2- 0 - CH21 - CH2-; provided that, when in formula (II) R1= R2=CH3, R
is a phenyl substituted by one or more halogen atoms, one or more alkyl or halo-alkyl groups, having from 1 to 3 carbon atoms.

2. Process for preparing the herbicide compounds of claim 1, characterized in that a trisubsti-tuted thiourea of formula (III) wherein R, R1 and R2 have the meanings defined in claim 1, is either:
a) treated with an oxidant in the presence of a base and in an inert solvent according to the reaction (1) in which n= 2, and R, R1 and R2 have the aforesaid meaning;
thereby obtaining the compounds of formula (I); these com-pounds then may be treated with triphenyl-phosphine in diethylether at about 0°C according to the reaction:

thereby obtaining the compounds of formula I in which n=1 and R, R1 and R2 have the aforesaid meaning; or b) reacted, in the presence of a slight excess of an organic base and in inert solvent, with an imidoyl chloride of formula (IV) in which R, R1 and R2 have the aforesaid meaning, for obtaining the compounds of formula I

(I) in which n= 1 and R, R1 and R2 have the aforesaid meaning;
or the above mentioned reactions a) or b) are carried out and the compounds of formula I in which n=1 or 2 and R, R1 and R2 have the aforesaid meanings are then treated with a strong anhydrous acid in an aprotic polar solvent at room temperature according to the reaction (I) (II) for obtaining the compounds of formula II, in which R, R1 and R2 have the meaning defined in claim 1.

3. Process according to claim 2, characterized in that the reaction 1:

wherein n, R, R1 and R2 have the meanings defined in claim 1, is performed by using bromine (Br2) or iodine (I2) as oxidant.

4. Process according to claim 2, characterized in that the reaction 4:

(I) (II) where n, R, R1 and R2 have the meanings defined in claim 1, is performed by using a halogenhydric or trihaloacetic acid as strong anhydrous acid.

5. Process according to claim ?, characterized in that in reactions 1 and 4, (1) (I) (4) (I) (II) methylene chloride (CH2Cl2) or chloroform (CHCl3) are used as solvent.

6. Herbicide compounds of general formulae:

(I) (II) wherein:
n= 1 or 2;
R= phenyl or phenyl substituted by one or more halogen atoms, one or more alkyl or haloalkyl groups having from 1 to 3 carbon atoms;
R1 and R2 (equal or different from each other) = alkyl C1 - C3, alkoxyl C1 - C3, or R1 amd R2 together are the group -CH2-(CH2)3-CH2- or the group -CH2-CH2-0-CH2-CH?; provided that when in formula (II) R1= R2= CH3, R is a phenyl substituted by one or more halogen atoms, one or more alkyl or haloalkyl groups, having from 1 to 3 carbon atoms.

7. Compounds according to claim 6, havin the for-mula I

(I) in which n = 1 and R, R1 and R2 have the meanings defined in claim 6.

8. Compounds according to claim 6, having the formula I

(I) in which n = 2 and R, R1 and R2 have the meanings defined in claim 6.

9. Compounds according to claim 6, having the formula II

(II) in which R, R1 and R2 have the meanings defined in claim 6.

10. Compounds according to claim 6, 7 or 9, in which R1 and R2 (equal or different from each other) = C1 - C3 alkyl.