C.hapfer .... I

Synthesis of cyanoamidinosubstituted­thiocarbamides (5), 1,3-diformamidino­thiocarbamide ( 6) and N-substituted­

f ormamidinof ormamidino­thiocarbamides ( 6)

Chapter· I

Cbaptcr - t

Synthesis of Cyanoamidinosubstitutedthiocarbamides (5),

1.3-diformamidinothiocarbamide (6) and N-substituted­formamidinoformamidinothiocarba mides (6)

Abstract

interaction of cyanoguanidine ( I) with phenylisothiocyanatc (2a) p -Cl-phenyli sothiocyanatc (2d), p-tolyl-isothiocyanate (2c), methyli sothio­cyanate (2d), ethylisothiocyanate (2e) and 1-butylisothuiocyanate (2f) and also with thiourea (3a) phenylthiourea (J b), mcthylthiourea (3c), elhyltJ1iourea (3d) and allylthiourea (3e) in presence of hydrochloric acid in acetone-ethanol medium have been reinvestigated, the products isolated in these reactions were characterised on the basis of conventional elemental analysis, chemical charncterestics and through IR and NM R spectral studies.

lntrod uction

Cynnoguanidine has been briefly studied by many r~searchers .

It is an important organ ic compound for its pharmacological, medicinal ,

biological, agricultural and industrial applications. 1•2 Cyanoguan1dine is a

bifunctional molecule. It has basic formamidino group at position 3 and a

cyano/nitrilo group at position 1. This molecule, therefore, is expected to

produce varities of certain interesting heteroacyclic and heterocyclic nitrogen,

nitrogen and sulphur containing organic compounds, tl1rough its reactive basic

a mino group and cyano group. As evid en t from the s tructure of

cyanoguanidine, it is quite likely that cyanoguanidine which is having basic

fonnamidino group react with various isothicyanates to produce related

cyanoamidino-substitutedthiocarbamides (5). Thi s reaction is akin 10 the

reac tio n of parent guanidine and isothiocyanates3·4 111 wh ich re lated

amidinothicarbamides were formed. Cyanoguanidine also has cyanamide like

s tructure. Interact ion of cyanamide and various thio ureas have been

R C Panpalia, Ph'.> Thooos 50

ChaptM I

investigated in sufficient details. s-• The initial product of this reaction was

shown lo be mono-formamidinomonosulphide salt, which was found lo be

readily rearranged into an amidinothiocarbamide salts. All these compounds

possess medicinal, pharmacological, agricultural and industrial values.

Therefore, it appeared interesting to reinvesltgalc the reactions

of cyanoguanidine with different isotluocyanates in section-A. While sect1on­

B comprises interactions of cyanoguanidine with different thiourea to isolate

cyanoam i di nosubs ti luted th iocarbam ides a net l , 3-di form am id i no-

thiocarbamides and N-substi tuted fonnamidinoformamidino1hiocarbamides

respectively which were used as intermediate in the synthesis of biurets and

Hector's bases. With the above objectives the interactions of cyanoguanidinc

has been carried out. The mechantsm of formation of products are as fol lows.

,.Jl '<C' - '<H - C - N , + C = N-R

II Acetone NC - NH - C - NH - C - NH - R

II H NH s

(I) (2)

Where R = phenyl, p-Cl-phenyl, p-tolyl, methyl, ethyl, I-butyl

II II NH S

(5)

112N - C - NH - C = N II

Acetone + HCl ---? ~N-C - NH - CJ~···· ~~ - C-NH - R

II II ... +" II 'IH

( I )

11,N - C NH - C - NH - C - NH - R II II 11 NII S NII

(6)

Aqueous ~ NnllCO,

NH NI I NH

1 (3)

Acetone

II II II [H2N - C - NH - C - S - C - NH - R]

NH NH NH

Where R = Ii, methyl, ethyl, allyl, phenyl

(Scheme - I)

Chaptei - I

Results and Discussion

Section - A

Cynnoamidinomethylthiocarbamide (Sd) :

Interaction o f cyanoguanidine ( I ) was carried oul with

melhyli sothiocyanate (2d) in acetone medium on water bath for 6 hours. It

was filtered in hot condition. The resultant filtrate was evaporated on room

condition. Needle shaped yellowish crystals were isolated. Yield 74% m p.

I 83°C.

Properties of (Sd) :

I. The compound is lemon yellow colour crystalline solid having m.p.

183°C

2. It contained nitrogen and sulphur elements.

3. Desulphurised with alkaline plwnbite solution.

4 . The Rf value was found to be 0.4, for dimrnne as solvcnl on silica

gel-G plate with layer thickness of 0.3 mm.

5 Elemental analysis ·

Elements Found Calculated

Carbon 29.85 30.57

Hydrogen 3.95 4.45

Nitrogen 44.43 44.58

Sulphur 20.3 8 20.38

6 From the analytical data the molecular formula was found to be

C4H

7N

5S.

7 IR Spectrum: The IR spectrum was carried 0 111 in KBr pellctes and

reproduced on Plate No. I R-1 . I The importan1 absorption can be

correlated as follows.

- :-.~ . Plait No. IR- 1.1

' ·" ~ \11[1\IC'• "UU'H"(I ,.,.-t ·,'

~ I

i

I Platt No. PMR- 1.1 I 1• ut:u :! u:,: •. m '~ ~m: I • lU•.tU "llPt . Ht

~' l.t

".:. ~Jm ... a " ' ,~ ,. .. ;: .~:.': :

* Jt Cf Ht.I: r1 1.1n. ff • .UC '"u 11.nt ffUOI .Ut ,_, un.n

Chapter· I

Absorption observed Assignment Absorption expected

(cm·') (cm·')

1080 > C = S stretching 1200-1 0509

1360 N . N> C = S groupmg 1380-105010

1660 > C - N H (imino) 1789-147 111

2850 C - N aliphatic 2940-27 10"

8. It formed picrate mp 163°C.

9. PMR : The PMR spectrum was carried out in C DCl1+ DMSO-d, arc

reproduced on Plate No. PM R- 1. 1. The important chemical shirts can be

mte'llreted as follows This specttum distinctly displayed signals due to

- C H1 protons at o 1.5 ppm and NH protons at o 7.2-7.3 ppm.

From the above properties and spectral analysis the compound

(5d) was assigned the structure as cyanoamidmornethy lth1ocarbamide.

NC - NH - C - NH - C - NII - CH, II II NII S

(5d)

Similarly, cyanoamidinophenylthiocarba mide (5a). cyano­

am1d1110-p-Cl-phe11yl1hiocarbamide (5b), cyanoamidino-p-1olyl1hiocarbam1de

(5c ). cya noam1di noe thyl1hiocarbarn ide (5c) and cyan oamidino-1-

butyhh1carbamide (5r) were prepared by interacllon of cyanoguamdine with

phenyhsothiocynate (2a). p -Cl-phenylisoth1ocyna1e (2b). /Holy lisoth1ocyna1e

(2c). e1hy lisoth1ocynate (2e) and /-bui 1. ti . . y tso 11ocynate (2r) Ill acelone medium

respeCtJvely by the above mentioned method in Experunent No ., t 6 . d listed 111 Table- I. · -

0 an

R C Panpol~. f'll O Thes.s 53

Chapter· I

Table - 1 •

Sr. Expt. Cyanoamidinosubstituted- Yield ('Y.•) m.p. °C

No. No. tbiocarbamide

I. 2 phenyl .. 82 187

2. 3 .. p-Cl-phenyl . 61! 147

3. 4 ... p-tolyl ... .. .. 6 1 163

4 . 5 ... ethyl 78 179

5. 6 . /-butyl 72 182

*Gave satisfactory C, H, N, and S analysis.

Section B

II Synthesis of 1,3-diformamidinothiocarbamide, hyd rochloride (6a)

(i) Interaction of cyanogua nidine and thioure:i in presence of aqueous

hydrochloric acid in acetone medium :

Interaction ofcyanoguanidine ( I) with thiourea (3a) in presence

of aqueous hydrochloric acid was carried out in acetone medium , duri ng

boiling the suspended cyanoguanidine went into the solution and a new product

was found to be gradually separated out. It was filtered in hot condition and

c1ysta llized with aqueous ethanol to get (6a), m.p. 265-66°C(d).

(ii) Interaction of cyanoguan idine and thiourea in presence of hydrogen

chloride (gas) in acetone and ether mixture as medium :

Interaction of cyanoguanidine ( I) was carri ed out with thiourea

(3a). To a suspension of cyanoguanidine and thiourea in e ther and acetone

( I: I) mixture, HCI gas was bubbled for I 0 minutes. and the reaction mixture

was renuxed. The suspended cyanoguanidine went into the solution and new

Chapter - I

product was found to be gradually separated out, it was filtered in hot condition

and c1ystallized with aqueous ethanol to get (6a), m.p. 265-66°C(d).

As investigated in the above reactions, the identical product with

m .p. 265-66°C(d) has been isolated in (i) and (ii). But in ( ii) yield of product

is more, probable reaction mechanism of format ion of (6a) may be stated as

follows.

C- NH- C"'N + HCI II NH

(I) Cyanoguanidine

HiN-C- NH- C- Nl-l- C-Nl-1 11 II II

2

NH S NH . 2HCI

(6a)

I .J-di formamidinothiocarbamide hydrochloride '

Properties of (6a) :

H2N-C-NH C=NH II I + NH Cl

II N- C- NH i 11 i

s (3a)

1 Thiourea

II 11/'11 2

[

HiN- C- NH-C-U- NH J NH NH NH . 2HCI

Unstable monosulphide

I. It is pale yellow, crystalline solid, 265-66°C(d).

2. It contained nitrogen, sulphur and chlorine.

3. It gave effervescence with sodium bicarbonate so it is acidic in nature.

4. Desulphurised with alkaline plumbite solution.

5. The Rf value was found to be 0.3 for dioxane as solvent on si lica gel-G

plate with layer thickness of 0.3 mm.

6. It formed picrate 229°C.

7. Equivalent weight was found to be 23 1.

8 Elemental analysis :

Elements Found Calculated

Carbon 15.29 15 .52

H ydrogen 3.98 4 3 1

Nitrogen 36. 13 36.22

Sulphur 13.69 13.79

9. From analytical data the molecular formula was found to be

C,H 10N,SCl2 .

I 0. IR Spectrum: The IR spectrum was carried out in KBr pelletes and is

reproduced on Plate no. IR- 1.2 . The important absorption can be

correlated as fo llows.

Absorption observed Assignment Absorption expected (cm·') (cm·1)

3435.6 N - H stretching 3500-30009

1638. 1 C = N stretching 1789- 14 71 10• 11

1523.9 > C = NH (imino) 1789-1471 11

grouping

11 99.7 C - N stretching 1340- 1250 10•12

991.9 N N > C ~ S grouping 1200-1 050 10• 12

11 . PMR : The PMR spectrum12•14 was carried out in CDC13+ DMSO-d,

and reproduced on Plate No. PMR-1 .2 This spectrum distinctly displayed

the signal s due to NH protons at Ii 6. 77 ppm.

The signals at o 3. 13 ppm is due to moisture in DMSO-d,, and

iS 1.25 ppm is due to DMSO.

100.00 r.r

D.DD-1----..-- - ..----.---r- - - - --r------..,---- --r-

~ - ~ ~ = ~ ~ -~

I

DS/03, 17 12:!56 R.CJSAJr.P.u.oro. Y: 4 aean1, 4 .0el'l·1 , flat , uooth, 1bu spl.i::ode:rt:S· 4A $'

Plote No. IR- 1.2

(I v -

y I Plate No. PMR- 1.2 I

ChaiJler - I

From the properties and spectral analysis the compound (6a)

was assigned the structure as 1,3-diformamidinothiocarbamide. hydrochloride.

H N- C- H C'- NH-C-NH 2

II 11 II 2

NH S NH . 2llll

(611)

II I N "-Phenylformamidinoformamidinotbiocarbamide,

hydrochloride (6b):

Interaction of cyanoguanidine ( I) and phenylthiourca (3 b) was

earned o ut in presence of hydrogen chloride gas 111 acetone-e ther medium. to

obtain sticky brown semisolid, which on trituration several times with

petroleum ether gives (6b), m.p . I R2°C .

Properties of (6b) :

It is dark yellow, crystalline solid. m.p . I 82°C

2. It contained nitrogen. sulphur and chlorine

It gave effervescence with sodium bicarbonate.

4 . Desulphuri sed with alkaline plumbite solution.

5 It formed picrate I 72°C

6 Elemental analysis :

Elements Found Calculated

Carbon 33.48 35.06

Hydrogen 3.72 4 .5S

Nitrogen 26.84 27.27

Sulph ur 10 21 10.39

7 .

8.

Chapl"' · I

From analytical data the molecular fonnula was found to be

C9H,~ .sc12.

IR Spectrum: The IR spectrum was carried out in KBr pe\letes and is

IR- I .3. The important absorption can be reproduced on Plate o.

correlated as follows.

Absorption ohserved Assignment Absorption expected

(cm·') (cm·')

3373 .9 N - H stretching 3500-30009

3 150.0 C - H(Ar) stretching 3150-3000"

1669.0 C ~ N stretching 1789-1471'0•11

1572.4 > C = NH (imino) 1789-1471 11

grouping

1394.7 C - N stretching 1340- 125010• 12

11 81.3 N> C = S grouping 1200- 105010.12 N

596.6 C - S stretching 800-60014

9 PMR: T he PMR spectrum12•14 was carried out in CDCl1~ DMSO-d6

and reproduced on Plate No. PM R-1.3 This spectrum distinctly displayed

the signals due to NH protons a t o 3.25-3.27 ppm. ArN H protons al

Ii 7.9-8.0 ppm and Arl l protons at 1i 6.90 ppm

The signals al o 2.55 ppm are due to moisture in DMSO-d• and

Ii 1.24 ppm are due to DMSO.

From the properties and spectral analysis 1he compound (6b)

was assigned the s truct ure as N"-pheny lform am id inoform am id ino ­

thiocarbamide, hydrochloride.

lDO.DD %T

A a

0.001+---~-----,----;------r-----,----- ,.--~ ~ ~ = ~ ~ ~ ~~

os103t17 14:40 R.C.tSAlf.P.U.OtD. X: .- scans, 4'.0c11-1, fht., 11110o\h, 1.bu sp1 .codur£.S•7R 'll1

'·' '~Cl ·~ ...

Plate No. ffi- 1.3

I Plnte No. PMR- 1.3 j

1 1 I

Chapler - I

C H - HN- C-NH- C-NH-C-NH 6

' II II II 2

NH S NH . 211CI

(6b )

Simi larly, N"-methylformamidinoformam1dinothiocarbamide

hydroch londe , (6c) "-ethyl formamidinoformamidi noth1ocarbam1 de

hydrochloride (6d) and N"-allylformamidinoformamiclinothiocarbamide

hydrochloride (6c) were prepared by the above mentioned as described in

Expt. No. 9 to I I and listed in Table-2.

Sr. Expt. ------thiocarbamide, hydrochloride Yield(%) m.p. oc No. No.

9 N"-methylformamidinoformamidino- 53 123

thiocarbamide, hydrochloride

2 10 N"-ethylforma1uidinofo1mamidino- 62 108

thiocarbamide, hydrochloride

3 I I N"-Allylformamidinoformamidino- 69 203 thiocarbamide, hydroch Jori de

'Gave satisfactory C, H, N, and S analysis.

R C Panpllia, Ph 0 Thesis 5 9

CNljlter - I

Experimental

The melting points of a ll the synthesised compounds were

iccoidcd usmg hot paraffin bath and are uncorrected. The carbon and hydrogen

analysis was carried out on Carlo-Ebra- 11 06 analyser. nitrogen cst1111anon

was earned out on Colman-N-analyscr-29 lR spectra were recorded on Perkin

t ime• specirome1er 111 the range 4000-400 cm·' 1n KBr pelle1cs. Pf\.IR spectra

were 1 ccorded on Bruker AC-300F spectromete r with TMS as interna l standard

using C' DCI, and DMSO-d, as solvent. The purity o f the compounds "as

checked on S1ltca Gel-G plates by TLC with layer thi ck11css of 0.3 mm All

chenuculs used were of A R grade (India make) excepl allylth iourea I ancaster

(Gc1 many make). RN Cs and phenylthiourea has been prepared by a l read}

kno" n methods."

t..xpcri mcnt No. I :

Preparation of cyanoamidinophenylth iocarbamidc (Sa) :

A mi1'1ure of cyanoguanidine (0 05 M) and phenylisothiocyana1e

(0 O~ M) was renuxed over a water bath in acetone medium for 4 hours. It

was filtered 1n ho1 condition. The resultan t filuate on evaporation g•ne (Sa).

yie ld 82%, mp. I 87°C.

Experiment No. 2 :

Prepa ration of cyanoamidino-p-Cl-phenylthioca rhamidc (Sb)

A mixture of cyanoguan1d1nc (0 05 M) and p-C'l-phenyl­

tsotluocyanate (0.05 M) was refluxed over a water bath in acetone medium

fo1 4 hours It was filtered in hot condition. The resultant filtrate on evaporation

ga\e (5 b). yield 68%, m.p. 147°C

Chapte1 I

Experiment No. 3 :

Prepa ra tion of cyanoamidino-p-tolylthiocarbamide (Sc) :

A mixture of cyanoguanidine (0.05 M) and p-tolylisothiocyanatc

(0 .05 M) was refluxed over a water bath in acetone medium for 4 hours. It

was filtered in hot condition. The resultant filtrate on evaporation gave (Sc),

yield 6 1 %, m.p. l 63°C.

Experiment o. 4 :

Preparat ion of cyanoamidinomethylthiocarba mide (Sd) :

A mixture of cyanoguanidine (0.05 M) and methyli sothiocyanate

(0.05 M) was refluxed over a water bath in acetone medium for 4 hours. lt

was filtered in hot condition. The resultant filtrate on evaporation gave (5d),

yield 74%, m.p . I 83°C.

Experiment No. 5 :

Preparation of cyanoamidinocthylthiocarbamide (Se) :

A mixture of cyanoguanidine (0 .05 M) and ethylisothiocyanate

(0 .05 M) was refluxed over a water bath in acetone medium for 4 hours. It

was fil tered in hot condition . The resultan t filtrate on evaporation gave (Se),

yield 78%, m.p . 179°C.

Experiment No. 6 :

Preparation of cyanoamidino-t-butylthiocarbamidc (Sf) :

A mixture of cyanoguanidine (0.05 M) and t-butylisothiocyanatc

(0.05 M) was refluxed over a water bath in acetone medium fo r 4 hours. It

was filtered in hot condition . The resultant filtrate on evaporation gHve (Sf),

y ield 72%, m.p. 182°C.

R C Panpaloa, Ph.O The$<s 61

Chl!>le<. I

Phenylthiourea :

Aniline (52 ml) was taken in 500 ml round bottom nask to it

cone HCI (52 ml) and was added, the reaction mixture "as warmr.d upto the

fonnation of soltd. It was then dissolved m minimum quantity of water, but

soluiion must be formed. To this solution of 40 gm of ammonium thiocyanate

di ssolved in I SO ml of distilled water was added It was hoiled it 011 gentle

bunscn fl ame untill the boiling solution became turbid due to the separation

of phenylthiourea This hot solution was poured in ice cold water. suddenly

,~hue solid was obtained yield 48 gm, m.p. 154°(

Experiment No. 7 :

Synthesis of l,3-diformamidinothiocarbamide, hydrochloride (6a) :

Interaction of tluourea with cyanoguamdrne has been carri ed

out 111 two different reaction conditions.

1) In presence of aqueous hydrochlo1 ic acid, in acetone medium

ii ) In presence of hydrogen chloride m acetone-ether med tum (I: I )

(i) A mixture of cyanoguanidrnc (0 I M), th1ourea (0 I M), HCI ( IO ml).

di stilled water ( 10 ml) and acetone (SO ml) was refluxed on bo1lmg water

bath for 8 hrs Dunng boiling suspended cyanogua11idme went 111to the solution

and a new product was found to be gradually separated out. It was filtered in

hot cond ition and crystall ized with aqueous ethanol to get pure (6a), yield

67 7%. m p 26S-66°C(d).

(ii) A mixture of cyanoguanidinc (0. I M), thiourea (0 I M), acetone (50

ml) and ether (SO ml) was taken. To thi s reaction mixture, di) hydrogen

chloride gas was bubbled ( aCI 16 g and 112SO, 25 ml) for 20 minutes Tl11 s

reaction mixture \\aS refluxed for 8 hrs Dunng bo1hng cyanoguanichne went

11110 thc solution and new product was fow1d to be separated out It was filtered

Chapter . I

in hot condition and crystallized with aqueous ethanol to get pure (6a), yield

79 .8%. m.p. 265-66°C(d).

(iii) Same reaction was carried out in benzene medium. In benzene medium

yield is 3 I%.

As investigated in above reactions the identical product with

m.p. 265-66°C(d) has been isolated in (i), (ii) and (iii) only yield is changed.

Experiment No. 8 :

Sy n thesis of N"-phe ny lfo rma midinoformam idinothiocarbamide,

hydrochloride (6b) :

The reaction mjxture ofcyanoguanidine (0. 1 M), phenylthiourea

(0. 1 M). acetone (50 ml) and ether (50 ml) was taken in round bottom flask .

Dry hydrogen chloride gas was bubbled for 15 minutes, to this reaction

1111xture. This reaction mixture was refluxed for 14 hrs. on water bath . The

sticky brown product was isolated, which after trituration with petroleum ether

several times gives (6b), y ield 61%, m.p. 182°C.

Experiment No. 9 :

Synthes is of N"-methylfor ma midinoformamid i noth ioca r bamid e,

hydrochlor ide (6c) :

The reaction mixture of cyanoguanidine (0. 1 M), methylthiourea

(0. I M), acetone (50 ml) and ether (50 ml) was taken in round bottom flask.

Dry hydrogen chloride gas was bubbled for 15 minutes, to this reaction

mixture. This reaction mixture was refluxed for 14 hrs. on water bath. The

sticky brown product was isolated, which after tritmation with petroleum ether

several times gives (6c), yield 53%, m.p. 123°C.

Ex1>criment No. 10:

Sy nth es i s of "-ethy lfo rm a midi nofo rmam id i no th ioca rba mid e,

hydrochloride (6d) :

The reaction mixture of cyanoguanid111e (0 I M). ethylth10urea

(0 I M), acetone (50 ml) and ether (50 ml) was taken in round bottom flask.

Dry hydrogen chlonde gas was bubbled for 15 111inu1es, to 1h1s reacuon

mixture. Thi s reaction mixture was refluxed for 14 hrs. on water bath. The

sticky brown product was isolated, which after trituration with petroleum ether

several times gives (6d), yield 62%. m.p. 108°C.

Ex1>crimcnt No. 11 :

Synthesis of N"-allylformamidlnoformamidinothiocnrbamide (6e) :

A mixture of cyanoguanidine (0. 1 M), allylthiourca (0. 1 M),

acc1one (50 ml) and ether (50 ml) was taken. Hydrogen chloride gas was

bubbled for 20 minutes, to this reaction mixture. The reaction mixture was

refluxed for 8 hrs on water bath A new dark yellowish crystalline product of

(6e) was found to be gradually separated ou1 yield 690' • 7 0 , m.p 203•c

R C P1npal11, Ph O Thesis 64

I . D. T. Tayade

2. D T. Tayade

3. M. G. Pnranjpc

4 P K Shrivastava

5 D. T. Tayade

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