A C T A U H 1 V E R S I T A T I S L O D Z I E N S I S
FOLIA CHIMICA 1, 1982
B ożenna M a zu rk ie w ic z
KINETICS OF THE REACTION OF THIOUREA WITH METHYL IODIDE
K i n e t i c s o f th e r e a c t i o n o f t h i o u r e a w ith m eth yl i o d i d e i n a q u e o u s s o l u t i o n s a t t h e t e m p e r a t u r e s 25°» 35° and 40°C h a s been i n v e s t i g a t e d .
The r e a c t i o n was fo u n d t o be d i t n o l e c u l a r . The r a t e o f t h e r e a c t i o n i s n o t a f f e c t e d by pH o f s o l u t i o n w i t h i n th e r a n g e 4 , 0 0 - 9 . 0 6 . A c t i v a t i o n e n e rg y o f t h e r e a c t i o n s i s 7 4 .0 7 K J/m o le K.
T h iu ro n iu m s a l t s , b a s i c compounds f o r o b t a i n i n g t h i o l s a r e m o st f r e q u e n t l y s y n t h e s i z e d by S - a l k y l a t i o n o f t h i o u r e a s w ith a l k y l h a l i d e s w h ich a r e e a s i l y a c c e s s i b l e com pounds and s e c u r e good e f f i c i e n c y o f S - a l k y l a t i o n r e a c t i o n .
K i n e t i c s o f t h e r e a c t i o n o f t h i o u r e a w it h s e l e c t e d a l k y l h a-l i d e s i n a l c o h o l e n v ir o n m e n t was exam ined b y P e a r s o n , S o b e l , S o n g s t a d [ 1 ] and B h a t t i and ft a 1 - h a n [ 2 ] . P e a r s o n , S o b e l and S o n g s t a d [ 1 ] d e te r m in e d a c o n s t a n t r a t e o f t h e r e a c t i o n o f t h i o u r e a w i th m e th y l i o d i d e i n m e th an o l a t th e te m p e r a tu r e 25°C u n d e r c o n d i-t i o n s o f p s e u d o - f i r s i-t - o r d e r r e a c t i o n a t h ig h e x c e s s o f m eth y l i o d i d e i n t h e s o l u t i o n . I n v e s t i g a t i o n s o v e r t h e k i n e t i c s o f th e r e a c t i o n o f t h i o u r e a w i th e t h y l b ro m id e an d a l k y l c h l o r i d e i n e th a n o l l e d B h a t - t i and R a l h a n [ 2 ] t o a c o n c lu s io n t h a t t h e r e a c t i o n s a r e d i m o l e c u l a r . The a u t h o r s e x p l a i n th e m echanism o f t h i s r e a c -t i o n by a sim p le e l e c t r o p h i l i c a t t a c k on s u l p h u r . T h is p a p e r p r e s e n t s th e r e s u l t s o f i n v e s t i g a t i o n s o v e r th e k i n e t i c s o f th e r e a c t i o n o f t h i o u r e a w ith m e th y l io d i d e i n aq u e o u s e n v iro n m e n t w h ich a llo w e d u s t o work o u t . a t h i o m e r c u r i m e t r i c m ethod o f qu an -t i -t a -t i v e d e t e r m in a t i o n o f h a l i d e a l k a n e s [ 3 ] . ¿ a t e r was ch o se n
a s a s o l v e n t i n o r d « r t o a v o id s i d e r e a c t i o n s w h ich may o c c u r i n a l c o h o l e n v ir o n m e n t when a c i d s a r e p r e s e n t i n i t .
E x p e r i m en tal
R e a g e n ts an d s o l u t i o n s : t h i o u r e a c r y s t a l l i z e d from w a te r t . t 180 °C , m e th y l i o d i d e w ere d i s t i l l e d and f r a c t i o n was c o l l e c t e d a t t h e te m p e r a t u r e 4 1 .5 - 4 2 ° C , I n i t i a l c o n c e n t r a t i o n o f a q u e o u s s o l u t i o n s o f t h i o u r e a was t e s t e d by d e s u l p h u r i z i n g [ 4 ] ._ C
oncen-t r a oncen-t i o n o f a q u e o u s s o l u t i o n o f m eth y l i o d i d e was d e te r m in e d by t h i o m e r c u r i m e t r ic m ethod [ 5 ] . P r o g r e s s o f t h e i n t e r a c t i o n b e -tw een t h i o u r e a an d m eth y l i o d i d e was i n v e s t i g a t e d by d e t e r m in a -t i o n o f -t h e i n c r e a s e i n c o n c e n t r a t i o n o f S - m e t h y l i s o t h i o u r e a .
C o n c e n t r a ti o n o f S - m e t h y l i s o t h i o u r e a was d e te r m i n e d a s f o l -lo w s: a sam ple o f t h e s o l u t i o n was i n t r o d u c e d t o a s e p a r a t o r y
f u n n e l an d t h e n e x t r a c t e d w i th t h e same volum e o f c a r b o n t e t r a -c h l o r i d e i n o r d e r t o rem ove u n r e a c t e d m e th y l i o d i d e . A p a r t o f t h e s o l u t i o n c o n t a i n i n g no m eth y l i o d i d e was t i t r a t e d w it h 5 • 1 0 ' 3 m ole/d w^ s o l u t i o n o f o - h y d r o x y m e rc u r ib e n z o ic a c i d (HMB) a t t h e p r e s e n c e o f d i t h i o f l u o r e s c e i n a f t e r S - m e t h y l i s o t h i o u r e a h a d b een decom posed t o t h i o l and ammonium s a l t s h a s b een a d -d e -d . The c o u r s e o f t h e r e a c t i o n was o b s e r v e d a t t h e te m p e r a tu r e 2 5 ° , 35° and 40°C.
I n i t i a l m o l ar c o n c e n t r a t i o n s o f t h e s u b s t r a t e s r a n g e d fr om 0 . 0 1 - 0 . 0 0 3 m ole /dm ^. The e f f e c t o f pH o f s o l u t i o n s was i n v e s t i -g a t e d w i t h i n t h e r a n g e 4 . 0 0 - 9 . 0 6 u s i n g B r i t t o n ' s and R o b i n s o n ’ s b u f f e r s and t h e e f f e c t of* h y d r o c h l o r i c a c i d on - th e c o u r se- o f r e a c t i o n was ex am i ned w i t h i n t h e c o n c e n t r a t i o n r a n g e 0 . 1 - 1 . 0 modWdm^;
g - - to [TM] • [ C H ,J ] a t * L*“ J Lw *3° w h e re : x - c o n c e n t r a t i o n o f S - m e t h y l is o t h i o u r e a . S uch c o u r s e o f t h e r e a c t i o n i s i n d i c a t e d by a l i n e a r d ep e n -d e n c e
F i g . ' l . C o u rse o f r e a c t i o n betw een t h i o u r e a and m e th y l i o d i d e i n [C H ,Jl - x
t h e sy stem l g - f TM] - T ~ “ f a t te,nPe r a t u r e 25 C
1 - [CH3J ] 0 - 0 . 0 3 9 2 m o le/d m3, [TM]0 - 0 . 0 1 5 9 m o le/d m 3 ( s c a l e I ) 2 - CCHoJlo - 0 . 0 1 6 9 m o le/dm 3,* [TM]0 - 0 . 0 3 1 9 m o l e / d r a 3 s c a l e I I I )
[ C H ,J] - x l g --- ¿—
Hi---[TM]q - x
a s a f u n c t i o n o f tim e p r e s e n t e d i n F i g , 1 an d 2 . [C H yj]Q and [TM] d e n o te i n i t i a l m o la r c o n c e n t r a t i o n o f m e ty l i o d i d e and o t h i o u r e a r e s p e c t i v e l y . F i g . 2 . C o u rse o f r e a c t i o n b e tw e en t h i o u r e a an d m e th y l i o d i d e i n [ C H ,J ] - x t h e sy stem l g [TM] - x ■ f ( t ) 1 - [CH3J ] 0 - 0 . 0 1 3 1 m o le/dm ?, Ct m]0 - 0.03^19 jo o le /d m 3 t/smp. 35°Ç ( s c a l e I I I ) , 2 - [CH3J] 0 - 0 .0 3 2 4 m o le/dm 3, [TMj0 - 0 .0 1 5 9 r m o le/ /d m 3 te m p . 35°C ( s c a l e I ) . 3 [CH3J ] 0 0 .0 1 5 7 m o le /d m 3, [ TM]0 -- 0 . 15c-i m ole/d m 3 te m p . 35 C ( s c a l e I I ) , 4 - LCHjJJq - 0 .0 3 1 8 m o le/d m 3, [TM]0 - 0 .0 1 5 9 m o le /d r a3 tem p . 40°C ( s c a l e I )
C o n s ta n t r a t e s o f r e a c t i o n s f o r g iv e n m easu re m e n ts s e r i e s w e re d e t e r m in e d b y» g r a p h i c m eth o d . F o r t e m p e r a tu r e s 25°» 35° a n d 4 0° th e y w ere 1 .8 9 * 10"*^, 5 .1 7 • 10"^ an d 7 . 5 3 ' 1 0 ” ^ (mole "’ 1s e c ” 1 dm^ ) r e s p e c t i v e l y . A c t i v a t i o n e n e r g y c a l c u l a t e d fro m A r r h e n i u s f o r m u l a i s 7 4 .0 7 K J/m o le K. I t was a l s o f o u n d t h a t v a r i a t i o n o f pH w i t h i n t h e r a n g e 4 .0 0 t o 9 .0 6 d o e s n o t a f f e c t t h e ch a n g e o f t h e c o u r s e o f k i n e t i c c u r v e s . Thus t h e i n v e s t i g a t e d p r o c e s s I s n o t a r e a c t i o n o f a c i d - - b a s e c a t a l y s i s t y p e . The p r e s e n c e o f h y d r o c h l o r i c a c i d w i t h i n t h e c o n c e n t r a t i o n r a n g e 0 . 1 - 1 mole/dm'* d o e s n o t i n f l u e n c e th e c o u r s e o f t h e ab o v e r e a c t i o n . REFERENCES-Cl 3 P e a r s o n R. G. , S o b e 1 H. , S o n g s t a d J. , J . A a. Chem. S o c . , 9 0 , 319 ( 1 9 6 8 ) . [ 2 ] B h a t t 1 A . M ., R a 1 h a n N. R ., J . I n d i a n Chem ., 12 , 969 (1 9 7 1 ) . [ 3 ] W r o ń s k i M. , M a z u r k i e w i c z B. , Chem. A n a l ., 2 0 , 621 ( 1 9 7 5 ) . [<•] W r o ń s k i M ., Chem. A n a l. , 5 , 101 ( 1 9 6 0 ) . [ 5 ] K a le n d a r z c h e m ic z n y , t . I , W arszawa 1954, 1 7 0 9 . D e p a rtm en t o f T e ch n o lo g y C h e m istr y I n s t i t u t e o f C h e m istr y U n i v e r s i t y o f Łódź
Bożenna M a zu rk iew icz
KINETYKA REAKCJI TIOMOCZNIKA Z JODKIEM METYLU
B adano k in e t y k ą r e a k c j i tio m o c z n ik a z Jod k iem m ety lu w r o z -tw o ra c h wodnych w t e m p e r a t u r z e 25 , 3 5, 40 °C . S tw ie r d z o n o , ż e J e s t t o r e a k c j a d w u c z ąs te c z k o w a . Na szy b k o ść r e a k c j i n i e wpływa pH r o z tw o r u w z a k r e s i e 4 . 0 0 - 9 .0 6 . E n e r g ia a k t y w a c ji r e a k c j i wy-n o s i 7 4 .0 7 k J /m o l K.
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