METAL-ORGANIC COMPOUNDS

(11) Reutov, Ο. Α., Bundel, Yu. G., J. Gen. Chem. U.S.S.R. 25, No. 12, 2295 (1955). Syn thesis of aromatic arsenoorganic compounds by way of double ...
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Uses

and

Economic

Preparation

of Organic Arsenic Compounds

ROLAND M. KARY

1

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Central Research Laboratories, American Smelting and Refining Co., South Plainfield, N. J.

O r g a n o a r s e n i c compounds, generally known as b a c ­ t e r i c i d e s f o r strictly m e d i c i n a l p u r p o s e s , a p p e a r i n ­ c r e a s i n g l y useful i n a g r i c u l t u r a l a s w e l l a s i n i n d u s ­ t r i a l pest c o n t r o l . The similarity in subatomic elec­ tronic configurations with nitrogen, phosphorus, a n d particularly with c a r b o n (greater electropositivity d u e to g r e a t e r d i s t a n c e f r o m nucleus) a p p e a r s to a c c o u n t f o r the v a r i e t y o f p o s s i b l e m o l e c u l a r s t r u c ­ tures o f t h e a r s e n i c a l f u n c t i o n a l g r o u p s , s o m e o f which exhibit pesticidal properties. The simplicity and f a v o r a b l e e c o n o m y o f t h e p r o c e d u r e s t o p r e ­ pare known a n d novel pesticidal compounds m a y b e e x p l a i n e d b y : the g r e a t v a r i e t y o f a r s e n i c a l f u n c ­ t i o n a l g r o u p s , such a s a r s o n i c a n d a r s i n i c a c i d s , arsine oxides, h a l i d e s , cycloarsines, etc., a n d their interchangeability; noninterference with carbon functionalities in the same molecule; a n d inde­ p e n d e n t substitution o n b o t h a r s e n i c a l a n d c a r ­ bon functional groups. Novel compounds were synthesized, including arsenomethane, arsenic-1,2disulfide, a n d derivatives, found to be potential agricultural pesticides. The arsonosiloxanes contrib­ ute m o l d - c o n t r o l l i n g properties to the industrial a p p l i c a t i o n s of the r e g u l a r silicones. Formation of organic nitrogen-base arsenites w a s investigated and r e s u l t e d in t h e d e t e r m i n a t i o n of t h e b a s i c c o n ­ stant (Kb = n X 10 or greater) as the controlling f a c t o r , i r r e s p e c t i v e of the structure of t h e o r g a n i c part. -8

^ ) f a l l t h e k n o w n o r g a n o m e t a l l i c s , t h e t h o u s a n d s of o r g a n i c a r s e n i c a l s h a v e r e t a i n e d a n i m p r e s s i v e l e a d i n n u m b e r a n d i n v a r i e t y . T h e c o n s i d e r a b l e efforts i n r e s e a r c h a n d d e v e l o p m e n t of these c o m p o u n d s h a v e p r o d u c e d n u m e r o u s m e d i c i n a l s , a few w a r f a r e agents, a n d some pesticides. I t n o w a p p e a r s t h a t o r g a n i c arsenicals h a v e s h i f t e d f r o m the p r e d o m i n a n t l y m e d i c i n a l a p p l i c a t i o n as g e r m i c i d e s t o a g r i c u l t u r a l uses as pesticides, w i t h m o r e t h a n a s u b s t a n t i a l p r o m i s e of c a r r y i n g t h e i r p e s t i c i d a l p r o p e r t i e s i n t o the p a p e r p u l p , t e x t i l e , a n d p l a s t i c s i n d u s t r i e s . T h e i m p r o v e m e n t of 1P resent address, Research L a b o r a t o r i e s , M e t a l & T h e r m i t C o r p . , R a h w a y , N. J. 319

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

320

ADVANCES IN CHEMISTRY SERIES

m a t e r i a l s o f e s t a b l i s h e d u t i l i t y b y i n c o r p o r a t i o n o f t h e arsenic a t o m i n t o m o l e c u l a r s t r u c t u r e s h a s b e c o m e a definite p o s s i b i l i t y . A r s e n i c i s a v a i l a b l e as a n e x t r e m e l y e c o n o m i c a l c o m p o u n d c o m m o d i t y i n t h e f o r m of arsenic t r i o x i d e , A s 0 , also c a l l e d w h i t e a r s e n i c . I t f o r m s s o d i u m a r s e n i t e w i t h c a u s t i c soda o r s o d i u m h y d r o x i d e . T h i s i s t h e s t a r t i n g m a t e r i a l f o r t h e s y n t h e s i s o f a t y p i c a l arsenical functional group, the arsono o r arsonic a c i d group. M a n y organic a r s e n i c a l s t r u c t u r e s f o l l o w v e r y closely t h e p a t t e r n o f n i t r o g e n , p h o s p h o r u s , a n d even carbon functionalities. A s illustrated i n Table I , the similarity of t h e subatomic 2

Table I. C s 2s 2p

Functionality of Similar Electronic Structures Ν s 2s 2p3

2

2

3

P s 2s 2p6

2

2

As s 2s 2p6

2

2

2

2

2

3s*3p*3d™

3s 3p»

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2

Outer shells R—NH R =NH R =N Amines basic

R—PH R =PH R ==P Phoshines less basic

R—AsHa R =AsH R =As Arsines feebly basic or amphoteric

(H C) N gas, B.P. = 2.9°C. R IUN Ammonium very basic

(H3Q3P liquid, B.P. = 40-2°C. R =P Phosphonium very basic

(HiC) As liquid B.P. = 59-60°C. R =As Arsonium very basic

2

2

2

2

3

3

3

4

CH "CH I ^CH? 2

2

1,2,3,4-Tetrahydronaphthalene

3

+

CH ^CH

4

+

2

3

CH

2

Ν I R

S

2

*

Not known

1,2.3.4-Tetrahydroquinoline

?

2

1,2,3,4-Tetrahydroarsinoline

2

Unknown

ÇH

As I R

3

2

2

^CHz

H C H C—CH I I H C—CH

+

4

/CHa As—As

N

Unknown

|

|

As—As

?

HC 3

Br

/

N

CH

3

Dimeric polyarsenomethane oil

Cyclobutane gas

Unknown

JT\ Unknown

/Mg-8r

(f y—As X=/ Mg—Br N

Phenylmagnesium bromide Carbon, Grignard

Phenylarsine di-(magnesium bromide) Arsenic, Grignard

e l e c t r o n i c c o n f i g u r a t i o n o b v i o u s l y results i n a s o m e w h a t s i m i l a r f u n c t i o n a l i t y f o r c a r b o n , n i t r o g e n , p h o s p h o r u s , a n d arsenic. H o w e v e r , t h e g r e a t e r e l e c t r o p o s i t i v i t y of arsenic o n account of t h e greater distance of the outer valence shell f r o m t h e nucleus p o i n t s t o as y e t u n k n o w n p o s s i b i l i t i e s of o r g a n i c a r s e n i c a l s t r u c t u r e s m o r e closely related t o organic carbon t h a n t o organic phosphorus o r nitrogen. A n o t h e r i m p o r t a n t f a c t o r responsible f o r b o t h t h e v a r i e t y a n d e c o n o m y o f o r g a n i c arsenical structures is their ability t o form functional groups, illustrated i n T a b l e I I , b y syntheses, t h e s i m p l i c i t y o f w h i c h i s a l m o s t u n e q u a l e d b y t h e r e a c t i o n s o f t h e o t h e r elements o f s i m i l a r e l e c t r o n i c s t r u c t u r e s . T h u s , t h e basic s y n t h e s i s f o r a l k y l a r s o n i c a c i d i s M e y e r ' s r e a c t i o n (S). I t e s s e n t i a l l y consists o f b r i n g i n g t o g e t h e r

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

321

KARY-ORGANIC ARSENIC COMPOUNDS Table II.

Synthesis of Typical Arsenical Functional Groups Functional Group

0

II

R-As-0~H

+

1

0~H

+

R arsonic acid Example of Reaction If R is alkyl

Meyer's Reaction

0"Να

0"'Na\ I >C1 " ~ ^O Na 0"Na

+

H C-C1

+

3

:

:As~0~Na 0~Na

>-

+

H 3 C

A s

+

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Methylchloride

:

+

H

3

C

" ~

A

s

_

r

N

a

+

+

N

a

C

1

+

Theor. intermediate

Disodium methylarsonate

Sodium chloride

Bart's Reaction:

0"Να I + :As—0"Na

. /