METAL-ORGANIC COMPOUNDS

Organosodium Compounds for Preparation of Other Carbon-Metal Bonds JOHN F. NOBIS, LOUIS F. MOORMEIER, and ROBERT E. ROBINSON

Downloaded by CORNELL UNIV on October 12, 2016 | http://pubs.acs.org Publication Date: January 1, 1959 | doi: 10.1021/ba-1959-0023.ch006

U. S. Industrial Chemicals Co., Division of National Distillers and Chemical Corp., Cincinnati, Ohio

The history a n d preparation of organometallic com pounds a r e discussed. The reactions of organo sodium compounds with various metal chlorides are given, including the conversion of organosodium compounds to the corresponding G r i g n a r d reagents by reaction with magnesium chloride. Although only a few of the organometallic compounds possible by reaction of a n organosodium compound with a metal halide have been p r e p a r e d , the w a y has been opened to economical, commercial syntheses of m a terials that are increasingly important in many fields.

Ο r g a n o m e t a l l i c c o m p o u n d s react w i t h o t h e r m e t a l s o r m e t a l h a l i d e s t o p r o d u c e c o m p o u n d s w i t h a n e w c a r b o n - m e t a l b o n d . T h i s t y p e o f r e a c t i o n w a s used i n t h e l a t e 1 9 t h c e n t u r y a f t e r F r a n k l a n d d i s c o v e r e d t h e first t r u e o r g a n o m e t a l l i c c o m p o u n d s , d i e t h y l z i n c (3) a n d m e t h y l m e r c u r i c i o d i d e (12), i n 1849 a n d 1853, r e s p e c t i v e l y . O t h e r d e r i v a t i v e s o f z i n c a n d m e r c u r y were p r e p a r e d i n s u b s e q u e n t y e a r s , b u t i t w a s n o t u n t i l 1900, w h e n G r i g n a r d ( 7 ) i s o l a t e d t h e first o r g a n o m a g n e s i u m c o m p o u n d , t h a t t h e o r g a n o m e t a l l i c field r e c e i v e d a t r e m e n d o u s i m p e t u s . T h e r e a c t i o n o f a n o r g a n o zinc, m e r c u r y , o r magnesium compound w i t h a metal, m e t a l halide, o r alkoxide t o f o r m a n e w organometallic c o m p o u n d was used considerably m o r e after t h a t t i m e . T w o g e n e r a l r e a c t i o n s h a v e been u s e f u l . organometallic compound b y another m e t a l :

T h e first c o m p r i s e s t h e r e d u c t i o n o f a n

RM + M'->RM' + M

(1)

A specific i l l u s t r a t i o n o f t h i s r e a c t i o n i s t h e w e l l k n o w n s y n t h e s i s o f a n o r g a n o s o d i u m compound from the corresponding organomercury derivative: I U I g + 3 N a -> 2 R N a + N a ( H g ) The

second

general

reaction

is the simple

(2)

displacement

reaction between a n

o r g a n o m e t a l l i c c o m p o u n d a n d t h e salt o f a n o t h e r m e t a l : R M + M ' X -> R M ' + M X

(3)

T h i s m a y b e i l l u s t r a t e d b y t h e c l a s s i c a l c o n v e r s i o n of a G r i g n a r d reagent t o a n o r g a n o cadmium compound : 2 R M g C l + C d C l -> RaCd + 2 M g C l 63 2

2

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

(4)

ADVANCES IN CHEMISTRY SERIES

64

F o r Reaction 1 t o proceed to the right, M ' must be a more active metal t h a n M : I f M a n d M ' a r e i n different g r o u p s i n t h e p e r i o d i c t a b l e , M ' m u s t l i e t o t h e l e f t o f M ; whereas i f M ' a n d M b e l o n g t o t h e same p e r i o d i c f a m i l y , M ' m u s t l i e b e l o w M . T h u s , a G r i g n a r d reagent s h o u l d u n d e r g o r e a c t i o n w i t h c a l c i u m o r s o d i u m , b u t n o t with beryllium or aluminum. T h e reverse i s t r u e r e g a r d i n g R e a c t i o n 3. F o r t h e d i s p l a c e m e n t t o t a k e p l a c e , M ' m u s t b e less a c t i v e t h a n M . T h e G r i g n a r d reagent s h o u l d r e a c t w i t h b e r y l l i u m chloride o r a l u m i n u m chloride, b u t not w i t h calcium chloride o r sodium chloride. I n theory, Reactions 1 a n d 3 provide f o r the replacement of a m e t a l i n a n organic c o m p o u n d b y a n y other m e t a l o n the periodic table.


Organoalkali Compounds T h e f o r m a t i o n of compounds containing n e w c a r b o n - m e t a l bonds t h r o u g h t h e use o f o r g a n o a l k a l i c o m p o u n d s i s a recent d e v e l o p m e n t d a t i n g f r o m t h e d i s c o v e r y i n 1930 ( T a b l e I ) b y Z i e g l e r a n d C o l o n i u s (14) o f t h e d i r e c t p r e p a r a t i o n o f o r g a n o l i t h i u m

Table I. Historical Development of Organometallic Compounds R Zn RHgl RMgX RLi 2

R N a (first) ΦΝΆ (first) Fine Na sand + high speed stirring Na dispersions Na (theoretical yield) NaCeNa (first large commercial use)

1849 1853 1900 1930 1932 1933 1935

(8 (12) (7) (U) (6) (5) (1)

1937 1951 1954

(9) (8) (10)

1955

(2)

c o m p o u n d s f r o m o r g a n i c h a l i d e s a n d m e t a l l i c l i t h i u m . T h e use o f o r g a n o l i t h i u m c o m p o u n d s as a l a b o r a t o r y t o o l f o r p r e p a r a t i o n o f a l k y l a n d a r y l d e r i v a t i v e s o f b o r o n , a l u m i n u m , silicon, g e r m a n i u m , lead, t i n , a n t i m o n y , a n d b i s m u t h , has been studied extensively b y G i l m a n a n d others d u r i n g t h e past 20 years. T h e e a r l y c h e m i c a l l i t e r a t u r e c o n t a i n e d a b u n d a n t references t o t h e t r a n s i t o r y existence o f o r g a n o s o d i u m c o m p o u n d s as i n t e r m e d i a t e s i n W u r t z r e a c t i o n s , b u t t h e direct preparation of a n organosodium compound f r o m sodium a n d a n a l k y l o r a r y l h a l i d e w a s b e l i e v e d i m p o s s i b l e . A c c o r d i n g l y , t h e first p r e p a r a t i o n o f s u c h c o m p o u n d s i n v o l v e d t h e i n t e r a c t i o n of s o d i u m w i t h d i a l k y l m e r c u r y o r d i a l k y l z i n c . T h i s technique w a s u s e d u n t i l 1933, w h e n G i l m a n a n d W r i g h t (5) p r e p a r e d a n o r g a n o s o d i u m c o m p o u n d (3-furylsodium) directly f r o m a n organic halide (3-chlorofuran) a n d metallic s o d i u m . T h e first p r e p a r a t i o n o f p h e n y l s o d i u m f r o m c h l o r o b e n z e n e a n d s o d i u m w a s r e p o r t e d b y B o c k m u h l a n d E h r h a r t (1). T h e r e a f t e r , a n u m b e r o f i n v e s t i g a t o r s , chiefly M o r t o n a n d G i l m a n , reported the p r e p a r a t i o n of a v a r i e t y of organosodium compounds f r o m organic chlorides a n d sodium m e t a l . U n t i l M o r t o n a n d F a l l w e l l (9) i n t r o d u c e d t h e use o f a fine s o d i u m s a n d , o r c r u d e d i s p e r s i o n ( 1 0 0 - t o 5 0 0 - m i c r o n s o d i u m p a r t i c l e s ) , c o u p l e d w i t h h i g h speed s t i r r i n g , the p r e p a r a t i o n of organosodium compounds f r o m a l k y l or a r y l chlorides a n d sodium w a s a t e d i o u s , t i m e - c o n s u m i n g process w h i c h o f t e n r e s u l t e d i n l o w y i e l d s . T h e studies of H a n s l e y (8) o n p r e p a r a t i o n a n d use o f finely d i s p e r s e d s o d i u m ( 1 0 t o 3 0 m i c r o n s ) i n t h e formation of phenylsodium i n 9 0 % yields opened a n e w era i n organosodium chemistry. Further studies i n t h e authors' laboratories (10) h a v e shown that phenylsodium a n d benzylsodium c a n be prepared i n nearly quantitative yields b y t h e use o f c a r e f u l l y c o n t r o l l e d r e a c t i o n c o n d i t i o n s w h i c h i n c l u d e t h e presence o f a s l i g h t excess o f f r e s h l y d i s p e r s e d s o d i u m . T h e r e a c t i o n b e t w e e n c h l o r o b e n z e n e a n d s o d i u m u n d e r these c o n d i t i o n s i s i m m e d i a t e a n d c o m p l e t e ; 1 m o l e o f p h e n y l s o d i u m m a y b e prepared i n only 20 minutes. T h i s reaction is easily adapted t o larger


NOBIS, MOORMEIER, AND ROBINSON-ORGANOSODIUM COMPOUNDS

65

scale a n d i s b e i n g u s e d i n d u s t r i a l l y o n a p l a n t scale. O t h e r o r g a n o s o d i u m c o m p o u n d s also a r e b e i n g u s e d i n p i l o t p l a n t a n d p l a n t scale. T h e l a r g e s t c o m m e r c i a l p l a n t u t i l i z i n g o r g a n o s o d i u m c o m p o u n d s i s o p e r a t e d a t T u s c o l a , 111., b y t h e U . S . I n d u s t r i a l C h e m i c a l s C o . , D i v i s i o n of N a t i o n a l D i s t i l l e r s a n d C h e m i c a l C o r p . T h i s p l a n t uses disodio-octadiene, a n organosodium compound made directly f r o m butadiene a n d sodium (2), i n t h e p r e p a r a t i o n o f Isosebacic a c i d , a m i x t u r e of 1 0 - c a r b o n d i b a s i c a c i d s . M a n y l a b o r a t o r i e s u t i l i z e o r g a n o s o d i u m c o m p o u n d s i n o r g a n i c s y n t h e s i s , as n o change i n t h e o r g a n o m e t a l l i c i n t e r m e d i a t e need b e m a d e i n s c a l e - u p t o p i l o t p l a n t o r p l a n t . F r e q u e n t l y , t h e h a n d l i n g o f o r g a n o s o d i u m c o m p o u n d s i s safer a n d m o r e c o n v e n i e n t t h a n h a n d l i n g G r i g n a r d reagents o r o r g a n o l i t h i u m c o m p o u n d s , w h e r e l a r g e quantities of ether usually are required.


Reaction of Organosodium Compounds A l t h o u g h m a n y m e t a l h a l i d e s s u c h as t i t a n i u m , z i r c o n i u m , b o r o n , a n d a l u m i n u m m a y b e r e d u c e d t o m e t a l s w i t h s o d i u m , these same m e t a l h a l i d e s r e a c t w i t h o r g a n o sodium compounds t o f o r m new carbon-metal bonds. Organosodium compounds m a y react w i t h the halides o r alkoxides of l i t h i u m , magnesium, m e r c u r y , boron, a l u m i n u m , silicon, g e r m a n i u m , t i n , lead, t i t a n i u m , zirconium, phosphorus, a n d iron. T h e organo metallic derivatives i n T a b l e I I c a n be prepared f r o m organomagnesium, l i t h i u m , o r sodium compounds.

Table II. Reaction of Organosodium Compounds with Metal Salts Halide or Alkoxide LiCl HgCb BCU AlCb SiCU GeCU SnCU PbCU TiCU ZrCU

Derivative RLi R Hg 2

R3B

R3AI R2S1CI2 R Ge R SnCl R Pb R2TiCl2 (cyclopentadienyltitanium dichloride) RîZrCh (cyclopentadienylzirconium dichloride) 4

2

2

4

RjP

PCI3

FeCh

R Fe (ferrocene) 2

M a g n e s i u m C h l o r i d e . W o r k was initiated i n the authors' laboratories t o study the conversion of organosodium compounds t o t h e corresponding G r i g n a r d reagents: R N a + M g C l -> R M g C l + N a C l 2

(5)

U n t i l recently, t h e reaction of a n organosodium c o m p o u n d w i t h m a g n e s i u m chloride h a d n o p o t e n t i a l v a l u e , because u s u a l l y t h e G r i g n a r d reagents were m o r e e a s i l y p r e pared than the corresponding organosodium compounds. D e v e l o p m e n t s i n t h e ease of p r e p a r a t i o n o f o r g a n o s o d i u m c o m p o u n d s , h o w e v e r , h a v e c h a n g e d t h i s s i t u a t i o n . T h e r e a r e cases w h e r e o r g a n o s o d i u m c o m p o u n d s c a n b e p r e p a r e d f r o m s t a r t i n g m a t e r i a l s w h i c h y i e l d G r i g n a r d reagents o n l y w i t h d i f f i c u l t y . F o r e x a m p l e , o r g a n i c chlorides a n d p a r t i c u l a r l y c e r t a i n a r o m a t i c o r heterocyclic chlorides react v e r y slug gishly w i t h magnesium, b u t yield organosodium compounds readily. A s a result, m a n y G r i g n a r d reagents w h i c h h a v e b e e n p r e p a r e d f r o m e x p e n s i v e i o d i d e s o r b r o m i d e s c a n be o b t a i n e d b y t h i s m e t h o d f r o m t h e less e x p e n s i v e c h l o r i d e s , o f t e n i n h i g h e r y i e l d s than from the reaction of a halide w i t h metallic magnesium. Other organosodium c o m p o u n d s , s u c h as d i s o d i o - o c t a d i e n e , o b t a i n e d t h r o u g h r e a c t i o n s w h i c h a r e c o m p l e t e l y u n k n o w n i n t h e field of o r g a n o m a g n e s i u m c h e m i s t r y , c a n b e c o n v e r t e d t o G r i g n a r d reagents w h i c h h a d b e e n u n a t t a i n a b l e . Often i t is advantageous t o convert a n organosodium intermediate t o t h e cor r e s p o n d i n g G r i g n a r d reagent p r i o r t o f u r t h e r r e a c t i o n . I n certain substitution r e a c t i o n s , t h e h i g h o r d e r of r e a c t i v i t y of t h e o r g a n o s o d i u m c o m p o u n d leads t o u n d e s i r a b l e side r e a c t i o n s o f w h i c h t h e G r i g n a r d reagent i s n o t c a p a b l e . F o r e x a m -


ADVANCES IN CHEMISTRY SERIES

66

p i e , t h e r e a c t i o n of a G r i g n a r d reagent w i t h acetic a n y h d r i d e m a y b e sufficiently c o n t r o l l e d t o p r o d u c e a m e t h y l k e t o n e i n excellent y i e l d . T h e c o r r e s p o n d i n g r e a c t i o n w i t h a n organosodium c o m p o u n d i n e v i t a b l y produces a significant q u a n t i t y of t e r t i a r y a l c o h o l . S i m i l a r l y , o - b e n z o y l b e n z o i e a c i d m a y be p r e p a r e d i n g o o d y i e l d t h r o u g h t h e action of phenylmagnesium chloride o n phthalic anhydride (Reaction 6 ) . T h e cor responding reaction w i t h p h e n y l s o d i u m cannot be brought under control, a n d t r i p h e n y l d i h y d r o i s o b e n z o f u r a n is t h e chief p r o d u c t ( R e a c t i o n 7) :

C H MgBr Downloaded by CORNELL UNIV on October 12, 2016 | http://pubs.acs.org Publication Date: January 1, 1959 | doi: 10.1021/ba-1959-0023.ch006

6

+

5

f

Y \ COOH Ο

OH

C

C H Na 6

5

+

|

\

c' < >

^

c

I^JL^

/° H

H

/ Î^C H CH 6

0

6

( 7 )

5

5

A n o t h e r e x a m p l e is t h e r e a c t i o n of a n o r g a n o m e t a l l i c c o m p o u n d w i t h c h l o r a m i n e t o y i e l d a p r i m a r y a m i n e . P r e s e n t i n d i c a t i o n s a r e t h a t t h i s c o u p l i n g r e a c t i o n proceeds m o r e s m o o t h l y w i t h a G r i g n a r d reagent t h a n w i t h a n o r g a n o s o d i u m c o m p o u n d . R M g B r + C 1 N H -> R N H 2

(8)

2

T h e r e a r e o t h e r r e a c t i o n s i n w h i c h t h e G r i g n a r d reagent gives a n e n t i r e l y d i f f e r e n t p r o d u c t t h a n does t h e o r g a n o s o d i u m c o m p o u n d — e . g . , i n r e a c t i o n w i t h b e n z alacetophenone. A n organosodium c o m p o u n d adds t o this m a t e r i a l t o y i e l d the ex p e c t e d t e r t i a r y a l c o h o l e x c l u s i v e l y . T h e G r i g n a r d reagent, o n t h e o t h e r h a n d , y i e l d s an alkylated ketone: Ο 0

OH

C H = C H — C — φ + R N a -> 0 C H = C H — C — φ

(9)

I R Ο

R

II

I

Ο

II

φ Ο Η — C H — C — φ + R M g X - > φ—CH—CH —C—φ (10) T o d e t e r m i n e i f m a g n e s i u m c h l o r i d e w o u l d react w i t h a n R N a c o m p o u n d , i t was first e s t a b l i s h e d t h a t t h e d e s i r e d m e t a l - m e t a l i n t e r c o n v e r s i o n r e a c t i o n w o u l d t a k e place t o f o r m t h e R M g C l d e r i v a t i v e . W h e n p h e n y l s o d i u m is refluxed w i t h toluene, b e n z y l s o d i u m i s f o r m e d q u a n t i t a t i v e l y , a n d c a r b o n a t i o n gives p h e n y l a c e t i c a c i d . P h e n y l m a g n e s i u m c h l o r i d e , o n t h e o t h e r h a n d , undergoes n o r e a c t i o n o n r e f l u x i n g w i t h t o l u e n e , a n d c a r b o n a t i o n of s u c h a m i x t u r e gives o n l y b e n z o i c a c i d . 2

φΝα

0

MgCl

toluene reflux

> 4>CH Na

toluene reflux

CO2

2

>0MgCl

> CH COONa

(11)

>0COOMgCl

(12)

2

CO2


NOBIS, MOORMEIER, AND ROBINSON-ORGANOSODIUM COMPOUNDS

67

A c c o r d i n g l y , a s u s p e n s i o n of p h e n y l s o d i u m i n t o l u e n e w a s p r e p a r e d a n d s t i r r e d a t room temperature f o r 2 hours w i t h magnesium chloride. T h e reaction mixture was h e a t e d u n d e r reflux f o r 2 h o u r s . C a r b o n a t i o n o n d r y i c e p r o d u c e d o n l y benzoic a c i d , i n d i c a t i n g t h a t n o b e n z y l o r g a n o m e t a l l i c h a d been f o r m e d . Clearly, phenylmagnesium c h l o r i d e h a d been p r o d u c e d . S i m i l a r l y , a suspension o f d i s o d i o - o c t a d i e n e i n d i m e t h y l e t h e r r e a c t e d w i t h t r i t a n e t o p r o d u c e t r i t y l s o d i u m ( t r i p h e n y l a c e t i c a c i d o n c a r b o n a t i o n ) before t r e a t m e n t w i t h magnesium chloride, b u t underwent n o reaction w i t h tritane after t h e magnesium c h l o r i d e t r e a t m e n t . T h u s , t h e o r g a n o m e t a l l i c c o m p o u n d w a s a s s u m e d t o be b i s c h l o r o m a g n e s i o - o c t a d i e n e , because t h e acids o b t a i n e d o n c a r b o n a t i o n were m i x e d 1 0 - c a r b o n dibasic acids. co N a C N a + CH 8

NaCgNa + M g C l


>

3

2

fcCHNa

2

>

fcCCOONa

(13)

> C l M g C M g C l —,

+ CH 3

8

C0

(14)

2

M i x t u r e of 10-carbon acids < B u t y l s o d i u m gave a similar reaction w i t h tritane without the magnesium chloride, b u t o n l y valeric acid was isolated o n carbonation when magnesium chloride was present. B u N a + ΦζΟΉ. -> BuNa + MgCl

2

fcCHCOONa

+ CH -> B u C O O M g C l

(15) (16)

3

C e r t a i n o r g a n o m e t a l l i c r e a c t i o n s r e q u i r e r e l a t i v e l y h i g h t e m p e r a t u r e s a n d some G r i g n a r d reagents a r e m o r e s t a b l e t h a n some o r g a n o s o d i u m c o m p o u n d s a t t e m p e r a tures above 100°C. I n these cases, i t w o u l d b e a d v a n t a g e o u s t o p r e p a r e t h e o r g a n o s o d i u m c o m p o u n d first i n a h y d r o c a r b o n m e d i u m a n d t h e n react w i t h a n h y d r o u s m a g n e s i u m c h l o r i d e . S e v e r a l a d v a n t a g e s a r e a c h i e v e d : C e r t a i n economies a r e r e a l i z e d w i t h respect t o t h e c o m p a r i s o n b e t w e e n s o d i u m a n d m a g n e s i u m ; h i g h e r y i e l d s m a y be r e a l i z e d ; a n d t h e G r i g n a r d reagent is p r e p a r e d e s s e n t i a l l y i n a h y d r o c a r b o n r a t h e r t h a n i n a n ether m e d i u m . S h o u l d a n ether reaction m e d i u m be desired f o r later reactions, t h e h y d r o c a r b o n solvent m a y be replaced w i t h a n ether after f o r m a t i o n of t h e G r i g n a r d reagent. L i t h i u m Chloride. I n 1940 G i l m a n a n d S w i s s (4) suggested t h a t t h e r e a c t i o n between a n organosodium c o m p o u n d and l i t h i u m chloride would yield a n organolithium compound. Recent work i n the authors' laboratories has shown that such a reaction does t a k e p l a c e . T h u s , a n e c o n o m i c a l r o u t e h a s been o p e n e d t o t h e p r e p a r a t i o n o f organolithium compounds i n hydrocarbon media. A l u m i n u m Chloride. T h e r e a c t i o n b e t w e e n a n o r g a n o s o d i u m c o m p o u n d a n d a l u m i n u m c h l o r i d e h a s n o t been r e p o r t e d p r e v i o u s l y . A n o r g a n o s o d i u m c o m p o u n d w i l l r e a c t w i t h a l u m i n u m c h l o r i d e o n l y i f a s m a l l a m o u n t of e t h e r i s p r e s e n t . I n benzene o r a l i p h a t i c h y d r o c a r b o n m e d i a , t h e r e i s n o a p p a r e n t r e a c t i o n b e t w e e n p h e n y l s o d i u m a n d a l u m i n u m c h l o r i d e . S i m i l a r l y , b u t y l s o d i u m does n o t r e a c t w i t h

Table III. Newer Reactions of Organosodium Compounds with Metal Halides RNa BuNa

Metal Halide BCh AlCh

ΦΝ&

SiCU

Na BuNa C H Na

CHsSiCU SnCl TiCU

0CH Na

PC1»

6

6

Bu AlCl (etherate) 2

0SiCl 02S1CI2

METAL-ORGANIC COMPOUNDS

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