Preparation of Alkyl Mercurials with Tetraethyllead

Preparation of Alkyl Mercurials with Tetraethyllead MYRON S. WHELEN Research Division, Organic Chemicals Department,

Downloaded by UNIV ILLINOIS URBANA-CHAMPAIGN on October 12, 2016 | http://pubs.acs.org Publication Date: January 1, 1959 | doi: 10.1021/ba-1959-0023.ch009

Ε. I. du Pont de Nemours & Co., Inc., Wilmington, Del.

The inexpensive preparation of alkyl mercurials by a unique method using tetraethyllead is described. The commercial methods of preparation of some use ful ones a n d the health hazards involved a r e given. The properties, utilization as fungicides a n d seed dis infectants, a n d effect on agriculture of alkyl mer curials are discussed.

I n 1923 m e t h y l m e r c u r i c i o d i d e was f o u n d b y G a s s n e r a n d E s d o r n (5) t o b e a p o w e r f u l f u n g i c i d e . K l a g e s (9) e x t e n d e d these findings t o a series o f a l k y l m e r c u r i c h a l i d e s , s h o w i n g t h e m t o b e 2 5 t i m e s as efficient as m e r c u r i c c h l o r i d e . T i s d a l e a n d C a n n o n (14) s h o w e d b y extensive tests t h a t t h e a l k y l m e r c u r i a l s a r e effective seed d i s i n f e c t a n t s f o r t h e c o n t r o l o f f u n g i c i d a l diseases. A l k y l m e r c u r i c h a l i d e s o f the t y p e R H g X were w e l l k n o w n , b u t t h e i r m e t h o d o f p r e p a r a t i o n , s u c h as the r e a c t i o n o f d i e t h y l z i n c a n d m e r c u r i c c h l o r i d e (12), w a s d i f f i c u l t a n d inefficient. T h e r e f o r e , t h e p r o d u c t s were m u c h t o o e x p e n s i v e f o r use a s f u n g i c i d e s . A m e t h o d was needed t o p r o d u c e these p o t e n t i a l l y v a l u a b l e c o m p o u n d s a t a reasonable cost f o r w i d e s p r e a d a p p l i c a t i o n . I n 1930, a m e t h o d f o r t h e p r e p a r a t i o n o f a l k y l m e r c u r y c o m p o u n d s w a s p a t e n t e d b y K h a r a s c h ( 7 ) , w h i c h c o m p r i s e d h e a t i n g m e r c u r y salts w i t h a n a l k y l d e r i v a t i v e o f q u a d r i v a l e n t l e a d , m o r e p a r t i c u l a r l y t e t r a e t h y l l e a d . T h i s p r o v i d e d t h e necessary eco n o m i c a l m e t h o d for t h e i r c o m m e r c i a l use. T h e r e a c t i o n i s a g e n e r a l one a n d m a y b e s h o w n as f o l l o w s : R P b + 2Hg+ + -> 2 R H g 4

+

+ R Pb + 2

(1)

+

Preparation B y utilizing this method, the following t y p i c a l , commercially i m p o r t a n t a l k y l mercurials m a y be prepared. E t h y l m e r c u r i c C h l o r i d e . T h i s was t h e first c o m p o u n d p r o d u c e d f o r c o m m e r c i a l use (8). I n t h e r e a c t i o n o f m e r c u r i c c h l o r i d e w i t h t e t r a e t h y l l e a d , t h e l a t t e r acts as a t r a n s a l k y l a t i o n agent : 2HgCl

2

+ P b ( C H ) -> ( C H ) 2 P b C l 2 + 2 C H H g C l 2

5

4

2

5

2

5

(2)

T h e r e a c t i o n m a y b e c a r r i e d o u t c o n v e n i e n t l y i n the l a b o r a t o r y . T e t r a e t h y l l e a d dissolved i n e t h y l alcohol is added gradually t o a suspension of mercuric chloride i n e t h y l alcohol. A f t e r heating a t 6 5 ° C . for 4 hours, the hot reac82

METAL-ORGANIC COMPOUNDS Advances in Chemistry; American Chemical Society: Washington, DC, 1959.

WHELEN—ALKYL MERCURIALS WITH TETRAETHYLLEAD

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t i o n m a s s i s c l a r i f i e d b y filtration. T h e p r e c i p i t a t e of e t h y l m e r c u r i c c h l o r i d e , w h i c h separates o n c o o l i n g , i s filtered off a n d r e c r y s t a l l i z e d f r o m e t h y l a l c o h o l . T h e y i e l d of e t h y l m e r c u r i c c h l o r i d e is 7 2 % of t h e o r y f r o m m e r c u r i c c h l o r i d e . I n c o m m e r c i a l p r a c t i c e , the m e r c u r i c c h l o r i d e is b a l l - m i l l e d w i t h a n i n e r t i n g r e d i e n t s u c h as t a l c , a n d the t e t r a e t h y l l e a d i s a d d e d a t i n t e r v a l s w h i l e m i l l i n g i s c a r r i e d o u t i n a b r i c k - l i n e d m i l l w i t h p o r c e l a i n b a l l s . C a r e is t a k e n t o p r e v e n t u n d u e t e m p e r a t u r e rise. T h e r e a c t i o n i s c a r r i e d o u t e s s e n t i a l l y i n d r y f o r m , a n d f u r t h e r i n e r t d i l u e n t i s a d d e d so t h a t t h e final m a s s has a n e t h y l m e r c u r i c c h l o r i d e c o n t e n t o f 2 . 0 % . I t is u t i l i z e d as s u c h . T h e great v a l u e o f t h i s m e t h o d o f p r e p a r a t i o n lies i n the m i l d c o n d i t i o n s e m p l o y e d a n d i n t h e t y p e o f e q u i p m e n t u s e d w h i c h a l l o w s m a n u f a c t u r e of large b a t c h e s r e q u i r i n g little processing. E t h y l m e r c u r i c c h l o r i d e , t h o u g h a v e r y efficient f u n g i c i d e , h a d a d e f i c i e n c y ; i t s h o w e d i n s t a b i l i t y w i t h e v o l u t i o n of d i e t h y l m e r c u r y , a h i g h l y v o l a t i l e c o m p o u n d w h i c h is v e r y t o x i c t o h u m a n s . A s t u d y of the r e a c t i o n suggested t h a t one o f t h e f o l l o w i n g s e c o n d a r y r e a c t i o n s m i g h t t a k e place w h i c h w o u l d e x p l a i n the f o r m a t i o n o f d i e t h y l mercury: R H g C l + R P b C l -> R H g + R P b C l 3

2

2

(3)

2

R P b + 2 R H g C l -> R P b C l , + 2 R H g 4

(4)

2

V a r i o u s e x p e r i m e n t s were u n s u c c e s s f u l i n d e t e r m i n i n g i f t h e s e c o n d a r y r e a c t i o n s w e r e t a k i n g p l a c e . B e c a u s e i t i s possible t o o b t a i n h i g h y i e l d s o f e t h y l m e r c u r i c c h l o r i d e , the m o r e p r o b a b l e e x p l a n a t i o n of t h e f o r m a t i o n of d i e t h y l m e r c u r y i s t h a t i t comes f r o m a d i s p r o p o r t i o n a t i o n e q u i l i b r i u m w i t h e t h y l m e r c u r i c c h l o r i d e (6). T h i s m a y come about i n the following m a n n e r : 2 C H H g C l ±+ ( C H ) H g + H g C l 2

5

2

5

2

(5)

2

T h e e v o l u t i o n o f d i e t h y l m e r c u r y c a n b e e l i m i n a t e d b y t h e use of b i s ( e t h y l m e r c u r i c ) phosphate, a m u c h m o r e stable c o m p o u n d . Bis (ethylmercuric) Phosphate. T h i s c o m p o u n d is p r e p a r e d (3) b y the i n t e r a c t i o n of m e r c u r i c o x i d e , p h o s p h o r i c a c i d , a n d t e t r a e t h y l l e a d . T h e t e t r a e t h y l l e a d acts as a t r a n s a l k y l a t i o n agent. T h e f o l l o w i n g r e a c t i o n s o c c u r , b u t the steps are c a r r i e d o u t s i multaneously : 2 H g O + 2 H P 0 -> 2 H g H P 0 + 2 H 0 3

2HgHP0

4

4

4

(6)

2

+ ( C H ) P b -> ( C H H g ) H P 0 + ( C H ) P b H P 0 2

5

4

2

5

2

4

2

5

2

(7)

4

T h e s y s t e m i s h i g h l y e x o t h e r m i c , t h e heat e v o l v e d b e i n g 26 k c a l . p e r m o l e o f m e r curic oxide. I n c o m m e r c i a l processes, t h e r e a c t i o n i s c a r r i e d o u t m o s t c o n v e n i e n t l y i n the s o l i d state b y the m e t h o d f o r p r e p a r i n g e t h y l m e r c u r i c c h l o r i d e . T h e t i m e o f m i l l i n g v a r i e s w i t h the a p p a r a t u s used a n d m a y b e as l o n g as 18 h o u r s . A f t e r t h e r e a c t i o n i s c o m p l e t e d , t h e r e a c t i o n mass i s d i l u t e d f u r t h e r w i t h a n i n e r t i n g r e d i e n t t o 5 . 0 % bis ( e t h y l m e r c u r i c ) p h o s p h a t e . I t i s s o l d as s u c h . E t h y l m e r c u r i c Acetate. E t h y l m e r c u r i c acetate (10), o r i g i n a l l y p r e p a r e d b y h e a t i n g d i e t h y l m e r c u r y w i t h acetic a c i d , i s p r e p a r e d r e a d i l y b y t h e r e a c t i o n of m e r c u r i c acetate w i t h t e t r a e t h y l l e a d : 3Hg(OCOCH ) 3

2

+ ( C H ) P b -> 3 C H H g O C O C H 2

5

4

2

5

3

+ C H Pb(OCOCH ) 2

5

3

3

(8)

I t is w a t e r - s o l u b l e a n d m a y be s e p a r a t e d r e a d i l y f r o m e t h y l l e a d t r i a c e t a t e . I t i s u t i l i z e d as a w a t e r - s o l u b l e f u n g i c i d e a n d is a c o n v e n i e n t s t a r t i n g m a t e r i a l f o r t h e p r e p a r a t i o n of a series o f a l k y l m e r c u r i a l s . E t h y l m e r c u r i c acetate w i l l condense readily, i n a n alkaline m e d i u m , w i t h compounds h a v i n g a replaceable hydrogen a t o m . T h e r e a c t i o n is a g e n e r a l o n e — f o r e x a m p l e , e t h y l m e r c u r i c acetate condenses w i t h p h t h a l imide to form Af-ethylmercuriphthalimide :


ADVANCES IN CHEMISTRY SERIES

84

C H HgOCOCH 2

5

3

+

ΝαΟΗ

+

Ν · HgC H

NH

2

+

5

NaOCOCH

3

+

H0 2


(9) E t h y l m e r e u r i c acetate reacts i n a s i m i l a r m a n n e r t o r e p l a c e h y d r o g e n o f m e r c a p t a n s , p h e n o l s , a n d c o m p o u n d s w h i c h enolize, s u c h as t h e 1,3-diketones. A n e x a m p l e of the use of e t h y l m e r e u r i c acetate is t h e p r e p a r a t i o n of N - e t h y l mercuri-p-toluenesulfonanilide. IV-Ethylmercuri-p-toluenesulfonanilide. T h e p r e p a r a t i o n of i V ~ - e t h y l m e r c u r i - p t o l u e n e s u l f o n a n i l i d e f r o m m e r c u r i c acetate, t e t r a e t h y l l e a d , a n d p - t o l u e n e s u l f o n a n i l i d e is d e s c r i b e d b y M o w e r y (11): 3Hg(OCOCH ) 3

2

+ ( C H ) P b -> 3 C H H g O C O C H 2

5

4

2

5

3

+

+ C H Pb(OCOCH )3 2

5

3

(10)

ΝαΟΗ

(H) M e r c u r i c o x i d e is d i s s o l v e d i n g l a c i a l acetic a c i d a t 9 5 ° C , a n d t h e m e r c u r i c acetate f o r m e d reacts w i t h t e t r a e t h y l l e a d a t t h e same t e m p e r a t u r e . A f t e r c o o l i n g , t h e s o l u t i o n is a d d e d t o a m i x t u r e of s o d i u m h y d r o x i d e a n d ice, a n d t o t h i s i s a d d e d a s o l u t i o n m a d e b y d i s s o l v i n g p - t o l u e n e s u l f o n a n i l i d e i n aqueous s o d i u m h y d r o x i d e . A f t e r s t i r r i n g a t r o o m t e m p e r a t u r e , t h e p r e c i p i t a t e is f i l t e r e d off a n d w a s h e d free o f a l k a l i w i t h w a t e r . A f t e r d r y i n g , a 9 4 % y i e l d o f i V " - e t h y l m e r c u r i - p - t o l u e n e s u l f o n a n i l i d e of 9 0 % p u r i t y , a s based o n the m e r c u r y content, is obtained. T h i s m a t e r i a l , after d i l u t i o n w i t h talc t o a 7 . 7 0 % c o n c e n t r a t i o n , i s s o l d as C e r e s a n M seed d i s i n f e c t a n t ( Ε . I . d u P o n t d e Nemours & Co.).

Properties of Alkyl Mercurials E t h y l m e r e u r i c c h l o r i d e , bis ( e t h y l m e r e u r i c ) p h o s p h a t e a n d i V - e t h y l m e r c u r i - p - t o l u e n e s u l f o n a n i l i d e a l l e x h i b i t v o l a t i l i t y . B i s ( e t h y l m e r e u r i c ) p h o s p h a t e is less v o l a t i l e t h a n e t h y l m e r e u r i c c h l o r i d e , w h i l e 7 V - e t h y l m e r c u r i - p - t o l u e n e s u l f o n a n i l i d e i s s t i l l less v o l a t i l e . E t h y l m e r e u r i c c h l o r i d e has a l o w v a p o r p r e s s u r e , s u b l i m e s r e a d i l y i n t o a i r a t 4 0 ° C , a n d has a m e l t i n g p o i n t of 1 9 5 ° C . I t can be steam distilled. I t tends t o evolve d i e t h y l m e r c u r y , and i n contact w i t h water v a p o r a n d organic materials this reaction is accel erated. A l l a l k y l m e r c u r i a l s are p o w e r f u l f u n g i c i d e s . E t h y l m e r e u r i c c h l o r i d e i s a b o u t 2 5 t i m e s m o r e p o w e r f u l t h a n m e r c u r i c c h l o r i d e as a f u n g i c i d e (5). I n c o m p o u n d s o f t h e t y p e C H H g X , t h e X p a r t o f t h e m o l e c u l e has s m a l l effect o n t h e f u n g i c i d a l a c t i v i t y of t h e c o m p o u n d b a s e d o n t h e m e r c u r y c o n t e n t , b u t t h e s o l u b i l i t y c h a r a c t e r i s t i c s , v e s i c a n t a c t i o n , a n d t o x i c i t y t o h u m a n beings a r e l a r g e l y c o n t r o l l e d b y X . 2

5


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85

Health Control


T h e h a z a r d s associated w i t h the m a n u f a c t u r e o f a l k y l m e r c u r y c o m p o u n d s a r e w e l l k n o w n (1). T h e y are p o t e n t s k i n i r r i t a n t s , a n d w i l l p r o d u c e severe v e s i c u l a t i o n and burns o n brief skin contact. I n a d d i t i o n , these o r g a n i c m e r c u r i a l s are a b s o r b e d t h r o u g h t h e s k i n as w e l l as t h e l u n g s , p r o d u c i n g s y s t e m i c , a c u t e , a n d c h r o n i c m e r c u r y p o i s o n i n g ( m e r c u r i a l i s m ) . A t p r e s e n t , m o s t codes designate a m a x i m u m a l l o w a b l e c o n c e n t r a t i o n o f m e r c u r y i n t h e a t m o s p h e r e f o r a n 8 - h o u r d a y a t 0.1 m g . p e r c u b i c m e t e r (4). D i s a b i l i t i e s r e s u l t i n g f r o m excess m e r c u r y a b s o r p t i o n c a n b e p r e v e n t e d . T h e p r e v e n t i o n i s one o f a d e q u a t e safety a n d h e a l t h m e a s u r e s i n t h e m a n u f a c t u r e o f these organic mercurials. A d e q u a t e ventilation is m a n d a t o r y i n operating buildings, a n d the m e r c u r y content i n air is determined continuously. A p r o g r a m t o m a i n t a i n t h e n o r m a l h e a l t h o f persons exposed t o t h e a l k y l m e r c u r i a l s has been effective. W o r k e r s are r e q u i r e d t o w e a r p r o t e c t i v e c l o t h i n g t h a t c o n s t i t u t e s a n effective b a r r i e r t o s k i n a b s o r p t i o n t o these o r g a n o m e r c u r i a l s . A m o n t h l y general p h y s i c a l examination w h i c h includes complete urinalysis a n d blood count is performed. U r i n a r y m e r c u r y levels o f o p e r a t i n g p e r s o n n e l are c h e c k e d before a s s i g n m e n t t o t h i s process. I f t h e u r i n a r y l e v e l c l i m b s t o 0.05 m g . o f m e r c u r y p e r l i t e r , w e e k l y a n a l y s e s are m a d e u n t i l t h e l e v e l d r o p s b e l o w 0.05 m g . I f t h e l e v e l c o n t i n u e s t o c l i m b a n d e v e n t u a l l y reaches 0.1 m g . p e r l i t e r , t h e m a n i s r e m o v e d c o m p l e t e l y f r o m c o n t a c t w i t h o r g a n i c m e r c u r i a l s u n t i l t h e m e r c u r y c o n c e n t r a t i o n d r o p s b e l o w 0.1 m g . p e r l i t e r (4). O n following this p r o g r a m , n o clinical indications of m e r c u r i a l i s m have occurred. T h e p r e s e n t m a x i m u m a l l o w a b l e c o n c e n t r a t i o n o f 0.1 m g . p e r c u b i c m e t e r o f a i r f o r t h e o r g a n i c m e r c u r i a l s (or 0.08 m g . p e r c u b i c m e t e r of a i r b a s e d o n e l e m e n t a l m e r c u r y ) a p p e a r s r e a l i s t i c . F r o m t h e a d e q u a c y o f h e a l t h p r e s e r v a t i o n experience of 6 y e a r s under this p r o g r a m , the p r a c t i c a l i t y of reduction of this level should be examined carefully.

Utilization as Fungicides T h e use o f a l k y l m e r c u r i a l s has been chiefly a s d i s i n f e c t a n t s f o r seeds a n d g r a i n s a n d f o r p r o t e c t i o n of n e w l y s a w e d w o o d f r o m f u n g u s a t t a c k , p a r t i c u l a r l y i n h u m i d c l i m a t e s (18). C o m m e r c i a l i z a t i o n o f t h e a l k y l m e r c u r i a l s as f u n g i c i d e s r e q u i r e d a r e l i a b l e t e s t i n g m e t h o d t o s h o w c o n c l u s i v e l y t h a t t h e y were efficient. T h e o r i g i n a l test m e t h o d w a s b a s e d o n t h e v o l a t i l e n a t u r e o f the c o m p o u n d s . T h e m e r c u r i a l was p l a c e d b e l o w t h e seeds o r g r a i n s i n a closed c o n t a i n e r , t h o u g h n o t i n c o n t a c t w i t h t h e m o r t h e i r s u p p o r t i n g m e d i u m . O n g e r m i n a t i o n , t h e s t a n d of seedlings w a s c o m p a r e d t o a s t a n d g r o w n w i t h o u t t r e a t m e n t . E x t e n s i v e t e s t i n g was c a r r i e d o u t u n d e r v a r y i n g c o n d i t i o n s a g a i n s t v a r i o u s f u n g i c i d a l diseases, s u c h as b u n t o r s t i n k i n g s m u t , seed r o t s , a n d b l i g h t s of cereal g r a i n s (14)- P r o t e c t i o n a g a i n s t n u m e r o u s f u n g i c i d a l diseases was g i v e n b y t h e a l k y l m e r c u r i a l s , i n t h a t m o r e seedlings a n d h e a l t h i e r seedlings were o b t a i n e d . T o secure m a x i m u m efficiency as a f u n g i c i d e , t h e p r o d u c t m u s t b e i n i t s m o s t s u i t a b l e p h y s i c a l f o r m a n d one w h i c h a l l o w s easy a p p l i c a t i o n . I n t h e e a r l y d e v e l o p m e n t , a f i n e l y d i v i d e d p r o d u c t d i l u t e d w i t h i n e r t s o l i d m a t e r i a l s (3), s u c h as t a l c o r c a l c i u m c a r b o n a t e , w a s u t i l i z e d as a d r y p o w d e r . I t i s m o r e feasible t o a p p l y i t t o seeds a n d g r a i n s b y a w e t m e t h o d a n d t h u s e l i m i n a t e t h e d u s t n u i s a n c e . T h e p r e s e n t t r e n d i s t o u t i l i z e a l k y l m e r c u r i a l s f r o m aqueous m e d i a , e i t h e r as s l u r r i e s o r as water-soluble compounds. T h e newly developed Af-ethylmercuri-p-toluenesulfona n i l i d e w a s f o r m u l a t e d t o b e a p p l i e d f r o m a w a t e r s l u r r y , a n d as C e r e s a n M seed d i s i n f e c t a n t i t is u s e d m o r e e x t e n s i v e l y n o w t h a n e t h y l m e r e u r i c c h l o r i d e a n d bis ( e t h y l mercuric) phosphate. I t is p a r t i c u l a r l y u s e f u l for t h e c o n t r o l o f b u n t o r s t i n k i n g s m u t ,


ADVANCES IN CHEMISTRY SERIES


86

seed r o t , a n d seedling b l i g h t s i n g r a i n s , a n d f o r t h e c o n t r o l of s e e d - b o r n e f u n g u s a n d b a c t e r i a l diseases w h i c h cause seed r o t i n c o t t o n . O n e g r a m of V - e t h y l m e r c u r i p - t o l u e n e s u l f o n a n i l i d e i s a m p l e t o k i l l a l l t h e spores i n 1 b u s h e l of w h e a t , w h i c h i s a r a t i o of 1 t o 27,000 o r 0 . 0 0 3 3 % . Other Mercurials. A n u m b e r of a l k y l a n d a r y l m e r c u r i a l s , p r e p a r e d b y m e t h o d s o t h e r t h a n b y t h e u s e of t e t r a e t h y l l e a d , a r e u t i l i z e d as f u n g i c i d e s (10). T h e y f a l l m a i n l y i n t o f o u r t y p e s : acetates, s u c h as 2 - m e t h o x y e t h y l m e r c u r i c acetate, p h e n y l m e r c u r i c a c e t a t e , a n d t h e a m m o n i a c o m p l e x of p h e n y l m e r c u r i c a c e t a t e ; u r e a s , s u c h as p h e n y l m e r c u r i u r e a a n d ( a c e t o x y m e r c u r i ) m e t h y l u r e a ; p h e n o l s , s u c h as ( h y d r o x y mercuri)nitrophenol a n d (hydroxymercuri)chlorophenol, and phenylmercuric salicylate; a n d others, s u c h as m e t h y l m e r c u r i c y a n o g u a n i d i n e . Effect o n Agriculture. T h e use of a l k y l m e r c u r i a l s i s w i d e s p r e a d f o r t h e c o n t r o l of f u n g i c i d a l diseases, e s p e c i a l l y those of w h e a t a n d c e r e a l g r a i n s . I t h a s m a d e p o s sible i n c r e a s e d y i e l d s of w h e a t , c o r n , c o t t o n , a n d o t h e r v i t a l c r o p s . A p p r o x i m a t e l y 3 5 % o f t h e seed u t i l i z e d i n these c r o p s is t r e a t e d w i t h a f u n g i c i d e , a n d of t h i s a b o u t 3 0 % i s t r e a t e d w i t h a n a l k y l m e r c u r i a l . T h e a c t u a l s a v i n g b y t h e use of a f u n g i c i d e is difficult t o d e t e r m i n e , b u t a 1 0 % y i e l d increase i s t o b e e x p e c t e d , o r f o r e a c h $1 s p e n t o n t h e p u r c h a s e of f u n g i c i d e s $ 2 0 i s r e t u r n e d . T h e e s t i m a t e d o v e r - a l l y e a r l y v a l u e o f t h e a l k y l m e r c u r i a l s i s of t h e o r d e r of $100,000,000, a n d t h e y h a v e c o n tributed measurably to our agricultural abundance.

Literature Cited (1) Ahlmark, Α., Brit. J. Ind. Med. 5, 117 (1948). (2) Buckton, J., Ann. Chem. Liebigs 109, 219 (1859). (3) Englemann, M. (to Ε. I. du Pont de Nemours & Co.), U . S. Patent 1,783,377 (Dec. 2, 1930). (4) Fleming, A. J., D'Alonzo, C. Α., Zapp, J. Α., "Modern Occupational Medicine," p. 139, Lea & Febiger, Philadelphia, 1954. (5) Gassner, G., Esdorn, I., Arb. biol. Reichanstalt Land-u. Fortwirtsch., Berlin-Dahlem II, 371 (1923). (6) Gilman, H., "Organic Chemistry," Vol. I, 2nd ed., p. 551, Wiley, New York, 1943. (7) Kharasch, M . S. (to Ε. I. du Pont de Nemours & Co.), U . S. Patent 1,770,886 (July 15, 1930). (8) Ibid., 1,987,685 (Jan. 15, 1935). (9) Klages, Α., Ζ. angew. Chem. 40, 559 (1927). (10) Leukel, R. W., Plant Disease Reptr. 37, 587 (1953). (11) Mowery, D. F. (to Ε. I. du Pont de Nemours & Co.), U . S. Patent 2,452,595 (Nov. 2, 1948). (12) Otto, R., Ann. Chem. Liebigs 154, 199 (1870). (13) Tisdale, W. H., Ind. Eng. Chem. 24, 745 (1932). (14) Tisdale, W. H., Cannon, W. N., Phytopathology 19, 80 (1929). RECEIVED for review May 10, 1957. Accepted June 1, 1957.


Preparation of Alkyl Mercurials with Tetraethyllead

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