Note: Descriptions are shown in the official language in which they were submitted.
20~2919
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~~he present invention is concerned with a process
for the prDduction of ~uanylthiourea by the reaction
of dicyandiamide with hydrogen sulphide in an organic
solvent and isolation t~ereof.
It is known that dicya~iamia~dds hydrogen sulphide
in aqueous or alcoholic medium with ~he~ormation of
guanylthiourea. In spite of long reaction times or
carryin~ out the reaction under pressure, the yield
and purity are unsatisfaCtory, especiallg as a result
of the formation of dithiobiuret.
Published Federal ~epublic of Germany Patent
~pecification DE-O~ 16 70 146 describes a process for
the production of addition compounds of .~-alkyl-
pyrrolidones with guanylthiourea. l;~hereas the yield of
addition product is, with 93%, satisfactory, in the
case of the described recrystallisation with alcohol,
mucb o, the desired product is lost so that this
process appears to be unsuitable for use on a technical
scale.
~ herefore, it is an object of the present invention
to provide a process for the production of guanyl-
thiourea which avoids tbe described disadvantages and
permits the production of guanylthiourea in good yield
and with high purity.
m~us, according to the present invention, there
is provided a process for the production of ~uanyl-
thiourea by the reaction of dicyand~mide with hydrcgen
2052919
--3--
sulphide in M-alkylpyrrolidone as solvent in the
presence of catalytically-actin~ additives, wherein,
as ca~alytically-acting addi~ive, there is used an
amine, ammonia and/or elementary sulphur with the
L ormation of an addition compound of L,uanylthiourea
and N-alkylpyrrolidone which is decomposed by treatment
1Jith an or~anic solvent followed by recovery of the
guanylt;~iourea as residue.
As dicyandiamide, there can be used the tec~nical
product which is commercially available with a purity
of grea~er than 9~.5,~ he hydrogen sulphide can be
used in pure form, mixed ~Jith inert gas or as a mixture
of hydrogen sulphide and carbon dioxide which is
obtained tec~nically. ~he ratio of hydrogen sulphide to
carbon dioxide can thereby vary in the ran~e of from
70:3C to 30:70~
An il-alkylpyrrolidone serves as reaction medium
for the reaction of the dicyandiamide with the hydrogen
sulphide. i~-meth~l-pyrrolidone is preferred but other
I~T-alkylpyrrolidones, for example l~-ethylpyrrolidone
and monomeric M-vinylpyrrolidone, can also be used with
good success. ~he ~i-alkylpyrrolidone can be used as sole
reaction medium or also in admixture with other solvents,
In particular, the addition of toluene or xylene has
proved to be useful, in which case it is preferable
to use ~ weight ratio of N-alkylpyrrolidone to toluene
and/or xylene of 1:1 to 1:1.50
20~2919
Accordin-, to t;-le inven~ion, it is i~portant to
add to the reaction rnixture the additives favourir~
the reaction oetween dicyandiamide and hydrogen sulphide.
~or tnis purpose, primary, secondary and tertiary amines,
for example ~ethylamine, diethylamine or tributylamine,
nave proved to be useful. The addition of ammonia has
proved to be especially useful, preferabl~l in an amount
of C.2 to 1.55, by weight and especially preferably of
0.2 to 0.6~ by weight, referred to the amount of dicyan-
diamide used. Furthermore, it has been surprisingly
ascertained that, besides ammonia ~s catalyst, also
the addition of elementary sulphu~ , preferably in an
amount of C.5 to 3.Cc by weight, referred to the dicyan-
diamide used, quite substantially influences the -;7eed
of the reaction and substantially suppres~es the fcr~-
ation of undesired by-products.
~ inally, we have found that recycled, impure mother
Liquor exerts an ~pecially strong catalytic influence
on the reaction, as is shown in the experimental series
No. 3 described ~.ereinafter. Over the course of ten
batches, practically quantitative yields were obtained,
the purity of the Juanylthiourea oein~-; over 980 in all
cases. T~us, thQ process according to the present
invention is outstandinsly suitable for continuous
operation since ~ardly any by-products are for~ed
which have to be eli~inatedO
20~29~9
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''~e reaction temperature is preferably of f om
7C to 120v, a 'e~perature of about 50C more prefer-
ably being maintained) favourable reaction speeds
'hereby bein~ obtained in the case of app-opriate
de~,rrees of reaction. Under optimum conditions, the
period of reaction is from 3 to 4.5 hours. Longer
reaction times of up to lO hours can be necessary
-J~en, for example, displacements in the catalyst
system favourinG the reaction occur.
~ he addition product of ,~,-alkylpyrrolidone and
guanylthiourea first o'~tained as inter~ediate product
can be obtained from the reaction medium in crystalline
form by coolin~. It can then be subsequently washed
with a small amount of the same solvent combination
as was used for the production. Subsequently, the
complex is treated with an anhydrous, hot extraction
agent in which case, surprisingly, only t~e ;~'-alkyl-
pyrroLidone goes into solution, the ~uanylthiourea
remainin~ behind as a practically colourless cryst-
zlline product.
T0luene has proved to be useful as extraction
agent. Ho~ever, there can also be used mixtures of
toluene wit~ one OL more other arene derivatives, for
example xylene, anisole, chlorobenzine or toluene,
and/or esters, for example carbonic acid dialkgl
esters, and ketones, for example diethyl ketone or
methyl isobutyl ketone.
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~,
~ he rl~ixin, ratio of to'uene to the other solvent
components can ~e ~aried ~ithin ~lide limits and can
be, or example, from 100:0 to 50:50.
7uanyltniourea can be used as an intermediate for
;he production of triazines, optical bLiuhtenin~ agents
and plant protection agents, as well as as a component
in fertilisers.
~ ne ~ollo~Jing ~xamples are given for the purpose
of illustrating the present invention:
Example 1.
Into a stirrer vessel eguipped 1ith a stirrer, a
thermometer, a cooler and a gas inlet pipe and con-
taining 130 parts by weight of toluene and 99 parts
by wei-~ht of l,-methylpyrrolidone ~reintroduced ~4
?artS by ~Jeight of dicyandia~ide, 0.1 part by weight
of tributylamine and 1 part by ~leight of ,uanylthiourea.
After flushin~ the reaction vessel with nitro~en, it
~;w~ heated and, at a temperature of about 7CC, the
introduction of hydro~en sulphid~wascom~enced. mhe
temperature ~las incrsased to 90C and the introduction
of hydrogen sulphide continued until the upta~e of the
theoretical amount of 34 parts by weig'nt was ended
aft-er a~out 10 hours.
~ he addition compound formed Gf ~uanylthiourea/
i7-methylpyrrolidone ~las so~led ~r.ile stirr~ng, filtered
off :Jith suction and subsequently washed with some
I~-methylpyrrolidone/toluene.
2~52~19
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The addition compound was separated by extracting
with hot toluene first at 60C and secondly at 85C.
By briefly boiling up the residue twice and again filter-
ing off, the guanylthiourea was obtained as a practically
colourless product with a purity of more than 98% and
with a melting point of 155 to 164~C. The yield was
114 g, corresponding to 96.5% of theory.
_xample 2.
Correspondin;~ ~ D ~xample 1, ~he follo;~in~ batches
were carried out ~it~ other catalysts an(1 other solvent
ixture:
exp. Ic~talyst , dicyan- solventlreaction I;lei~h Iyield
I;o. (parts ' diamide ! (parts time out ('')
by ~:/t~ I (parts I by wt.), hrs./ I parts ,.,
,~ wt.)' I( 8~ ~ ,~ ~lt.) _ ~
1 0.8 GT-H 'I 84 1 ~47.5 8/90 07.2 90.7
2 0.1 ~3A ', 84 ~ 99 I~.l;P 9/~8 jll2.3~5.5
0.8 ~TH , 1 15C ,
j ¦toluene
3 0 03 T3A ~ 84 ~27~ p 12/90 ~112.5I,95.2
I I toluene
4 O.G6 TBA 84 5C ~IP 16/35 ,112.8 95.5
G.8 GTH 150
toluene
52 S 3 84 ~oluen~ 4 8/ 114,3¦~6.7
61 3 S , 84 , 13G 4 5~ 114.7',97.1
i '~oluene
. ._ j ,
~TIJ = ,uanylthiourea
~A = tribu~ylamine
;~IlP = ;I_methylpyrrolidone
S = sulphur
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'he above _xamples show ~he clear acceleration
of the reaction by rneans of ~he use of a~monia and/or
sulphur as catalyst s~stem in t'ne case o~ the p~oduction
of ~uanylthiou~ea.
ln each case, the addition compound was separa~ed
off ~ extraction ~Jith toluene. Analogous results ;lere
obtained with mixtures of toluene ~Jith various butanol
derivatives, ketones and esters, for example carbonic
acid esters, in a ratio of toluene to the other solvent
com~onent of 1:1.
~xample 3.
In this series of 10 experiments, there is described
the influence of the recycled mot~er liquor on the
formation of guan~lthiourea.
~ serial experi~ent ~as carried out ~lith 8 ~atches
with the reuse of the mother liquor at 90C. Th2
startin~ reaction mixture (experiment 1) contalned
84 parts by wei~ht of dicyandiamide, 150 parts by
~ei~ht of toluene, 99 parts by l:/eight of I,-met~yl-
pyrrolidone (NllPJ and 0.1c,~ of tributylamine and 0.80,~
of guanylthiourea referred to dicyandiamide.
~ or experiments 2 to 8, to f esh dicyandiamide
was added the amount of toluene ~iven in the follo~qing
Table (in each case 150 parts by lJeight), together ;Jith
the pa~ticular given amount of mother liquor from the
preceding experiment (= residue of the reaction medium
after distilling off the toluene and separation of
the product), whereby, in addition, ~.5 g of fresh
c 2~52919
;il ~? wer~ nded in each experiment.
, I ca~al~st, reaction mother H2S ,reactionlwPi-n yieid ,
:o. (parts I medium liquor I ta~e- ' ti~e ! OUt ' ,,
by wt.) I (parts (parts ~, up I (hrs.)l(~arts
by wt.) by wt.) ( parts ) vy ;Jt~
1 I ~y .r ~ ~ , ~0 I Ll llC~.9 ~ ~2.2
toluene
¦ 2 _ 150 93.3 ~ 35.5 ¦ 4.3 jllb.~ ¦ 98.6
! 3 ~ 15~ 94 1 33-4 ! ~-5 ~117-7 1 95.6
¦ 4 _ 150 lG0 ~ 34.5 1 3.5 ill6.8 ' 98.~ j
1 5 _ 150 lG2 11 32.4 l, 4.4 ~ .2 ~00.0 ,
o ¦ _ 15C lG9 1 33.5 3.& , 117 99.o
7 ¦ - 15G 112 1 ~2.2 , 3.7 l~117.7 99.6
~ 15~ 112 ' 34,7 4.6 '117.9 99.8
-methylpyrrolidone
In t'ne case of ex~eriments 6 to ~, hydrogen
sulphide was used in ad~ixture with 40 parts by
volume of carbon dioxide.
Example 4.
Correspondin~ to Exa~ple 3, a series of experi-
ments was carried out with ammonia as catalyst and
with the reuse of the mother liguor. ~he startin-
~reaction ~ixture was as in Example ~ e~cept that
1.2 parts by l~ei~ht of am~onia was used as c3tal,~s~.
In batch 2, to the mother liquor were addition311~
added 2,0 parts by weir,llt of ammonia and 0.5 parts
by weight of fresh ~iiP. In batch ~ were addition311
added 2.2 p3rts by weir,ht of a~monia an~ 0.5 pa~ts
by wei~hl~ of fresh l~ilP.
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-L0_
~ 'he reaction temperature was 90C. ~he hydro~en
sulphide was introduced in the form of a mixture ~7ith
50,~ by volume of carbon dioxide.
_,
exp. cataLyst reaction mother ¦ -~2S ¦reaction ~Jeigh Yield
;,o. (parts medium liquor time out
bg wt.j (parts (parts j take- ¦ (hrs ) (parts
~y wt.) by wt.)¦ (parts ~y ~Jto)
. , , ,
1 1.~ 995~ollP ~ 31.51 12.2 110.9 93.8
~oluene
2 2.0 150 89.8 33.6 7.5 118.1 99.9
3 2.2 150 95.1 1I n.d.~.3 118.0 99.9
1 minor amounts result from the volatiLity of
the toluene
n.d. = not determined
