10 Synthetic Route to the A c i d Portion of Permethrin
M. S. GLENN and W. G. SCHARPF
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FMC Corp., Agricultural Chemical Division, Box 8, Princeton, N.J. 08540
The d i e n e was originally p r e p a r e d by F a r k a s , Kourim, and Sorm (1) by the f o l l o w i n g s y n t h e t i c r o u t e :
A l t h o u g h the P r i n s r e a c t i o n proceeded i n good yield w i t h o n l y a s m a l l amount o f polymer f o r m a t i o n , a c e t y l a t i o n and r e d u c t i o n r e q u i r e d l a r g e amounts o f p y r i d i n e and z i n c which were too c o s t l y f o r c o m m e r c i a l i z a t i o n . The o v e r a l l yield o f 1,1-dichloro-4-methyl-1,3-pentadiene was o n l y 38%. Our r e a c t i o n sequence c o n s i s t e d o f t h r e e s t e p s w i t h an overall yield o f 57%, a l t h o u g h y i e l d s were not maximized. Only low c o s t , c o m m e r c i a l l y - a v a i l a b l e c h e m i c a l s were u s e d . The Darzens-Kondakov reaction o f 1 , 1 - d i c h l o r o ethene w i t h i s o b u t y r y l c h l o r i d e proceeded as f o l l o w s :
116
In Synthetic Pyrethroids; Elliott, M.; ACS Symposium Series; American Chemical Society: Washington, DC, 1977.
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10.
GLENN
AND
SCHARPF
Permethrin
117
Synthesis
The reaction was developed by Heilbron, Jones, and J u l i a (2); improved by Soulen et al. (3) who used carbon t e t r a c h l o r i d e as a d i l u e n t ; and f i n a l l y by A t v i n , Levkovskaya, and Mirskova (4) who used po tassium carbonate to remove a mole of hydrogen c h l o r ide. The thermal removal of hydrogen chloride was difficult for t h i s compound and required steam dis tillation followed by f r a c t i o n a l distillation. We found that removal of hydrogen chloride was best achieved by using sodium carbonate. The reaction pro ceeded smoothly at 16 gram moles and gave a minimum of 67% distilled y i e l d . Other Lewis acids such as stan nic chloride and f e r r i c chloride gave zero or a poor yield respectively. The reduction of the ketone to the alcohol was attempted by the c a t a l y t i c method of Adams (5) (platinum oxide and ferrous c h l o r i d e ) , but s e l e c t i v e reduction was not obtained.
Ο
OH
A standard reduction (60 using an equimolar amount of commercial aluminum isopropoxide gave an 82% y i e l d of the alcohol. When one-quarter mole of f r e s h l y pre pared aluminum isopropoxide was used per mole of ketone, a 62% y i e l d of the alcohol was i s o l a t e d . Equimolar amounts of f r e s h l y prepared isopropoxide afforded a 94% y i e l d of the d i s t i l l e d a l c o h o l . The Prins reaction of isobutyraldehyde and 1,1-dichloroethene d i d not give the desired alcohol because of a l d o l formation. The dehydration of the alcohol gave 1,1-dichloro4-methyl-l,3-pentadiene and smaller amounts of the corresponding 1,4-diene. The r e s u l t s from various a c i d i c c a t a l y s t were shown in the following table.
2)
OH H+ Acid Clay K S 0 * pTSA 2
2
(Superfiltrol)
7
KHSO4 H3PO
Superfiltrol*
1) 89% 26 20 14 57 83
2) 0.5%
9 0.5
*Azeotropic removal
In Synthetic Pyrethroids; Elliott, M.; ACS Symposium Series; American Chemical Society: Washington, DC, 1977.
Downloaded by UNIV OF LIVERPOOL on October 6, 2015 | http://pubs.acs.org Publication Date: June 1, 1977 | doi: 10.1021/bk-1977-0042.ch010
118
SYNTHETIC
PYRETHROIDS
The b e s t commercial method used 1.0-1.5% o f a c i d c l a y a t 100-120° and an i n e r t gas t o a i d in t h e removal o f water. A f t e r t h e e v o l u t i o n o f water was completed the d i e n e was d i s t i l l e d d i r e c t l y from t h e r e a c t i o n flask. S i n c e t h e 1,4-diene may be i s o m e r i z e d t o t h e 1,3-diene w i t h £-toluenesulfonic a c i d , a t o t a l y i e l d o f 90% was o b t a i n e d . The a c i d c l a y , S u p e r f i l t r o l , was a low v o l a t i l e m a t e r i a l o b t a i n e d from t h e F i l t r o l Company, Los A n g e l e s , C a l i f o r n i a . The r e a c t i o n o f t h e d i e n e w i t h e t h y l d i a z o a c e t a t e as d e s c r i b e d by F a r k a s (1) was r e p e a t e d t o g i v e a 37% c o n v e r s i o n and a 71% y i e l d o f e t h y l 3 - ( 2 , 2 - d i c h l o r o vinyl)-2,2-dimethylcyclopropanecarboxylate. The c o s t e v a l u a t i o n f o r 1 , l - d i c h l o r o - 4 - m e t h y l 1,3-pentadiene gave a u n i t c o s t o f $1.87 p e r pound based on t h e p r i c e o f raw m a t e r i a l s as o f October 1975. The c o m m e r c i a l i z a t i o n o f t h e p r e p a r a t i o n o f e t h y l d i a z o a c e t a t e and its r e a c t i o n t o form t h e e t h y l e s t e r o f t h e p e r m e t h r i n a c i d would be s i m i l a r t o t h a t o f p a s t a l l e t h r i n s y n t h e s i s (7).
1. 2. 3. 4. 5. 6. 7.
Literature Cited J. F a r k a s , P . K o u r i m , and F. Sorm, Coll. Czech. Chem. Comm., 24, 2230 (1959). I. H e i l b r o n , E . R. J o n e s , and M. Julia, J. Chem. Soc., 1949, 1430. R. L. S o u l e n , D . G . K u n d i g e r , S. S e a r l e s and R. A . Sanchez, J. O r g . Chem., 32, 2661 (1967). A . S. A t a v i n , G . G . Levkovskaya and Α . Ν . M i r s k o v a , J. O r g . Chem. (USSR), 9, 318 (1973). R. Adams, J. Amer. Chem. Soc., 47, 3064 (1925). A . L. W i l d s , O r g a n i c R e a c t i o n s , I I , 178 (1944). H . J. Sanders and A . W. Taft, I n d u s t r i a l and E n g i n e e r i n g Chem., 46, 414 (1954).
In Synthetic Pyrethroids; Elliott, M.; ACS Symposium Series; American Chemical Society: Washington, DC, 1977.
