2 Chlorophenylalkyl-substituted Carboxylic
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Acids and Silanes Designed as Adhesion Promoters J. G. O'REAR and P. J . SNIEGOSKI Naval Research Laboratory, Washington, D . C. 20390 F. L . JAMES Miami University, Oxford, Ohio 45056
Eight new surface active molecules having a terminal p-chlorophenyl substituent, a polymethylene
spacer, and reac-
tive carboxyl or alkoxysilane groups have been prepared. Such structures form monolayers which promote adhesion between a solid substrate and an organic resin because they expose a relatively high energy chlorophenyl outer surface which is easily wet by the resin. Preparative methods are outlined for the monocarboxylic CO H,
acids p - C l C H ( C H 2 ) n - 1 6
4
(where n is 12, 14, 18, and 20), for the dicarboxylic
2
acids p - C l C H ( C H ) 1 2 C H ( C O H ) C H C O H and p - C l C H 4 6
4
2
2
2
(CH ) CH(CO H)CH CH CO H, 2
12
2
2
2
silanes p - C l C H C H C H S i ( O M e ) 6
Si(OEt) . 3
criteria.
4
2
2
6
and for the
2
2
3
and
substituted
p-ClC H CH CH26
4
2
The compounds are characterized by conventional NMR
spectra establish the para position of the
chloro substituent. GLC shows that the purities of the acids generally exceed 97.5%. Principal impurities are the unchlorinated analogs and lower homologs.
" \ T o s t c o m m e r c i a l finishes for glass fiber f o r m surfaces w h i c h are n o t r e a d i l y w e t b y t h e resins u s e d for glass fiber i m p r e g n a t i o n . T o c o r r e c t this d e f i c i e n c y i n a d h e n s i o n , r e d e s i g n of existing " c o u p l i n g a g e n t s " or " a d h e s i o n p r o m o t e r s " has b e e n p r o p o s e d (16). T h e n e w concept u t i l i z e s m o n o l a y e r s of a p p r o p r i a t e d e s i g n f o r p r o m o t i n g a d h e s i o n b e t w e e n a n o r g a n i c r e s i n a n d a s o l i d substrate (see F i g u r e 1 ) . T h e n e w structures r e p o r t e d here f e a t u r e a t e r m i n a l c h l o r o p h e n y l substituent 10 Alexander; Interaction of Liquids at Solid Substrates Advances in Chemistry; American Chemical Society: Washington, DC, 1968.
2.
11
Adhesion Promoters
O'REAR E T A L .
e x p o s i n g a n outer surface w h i c h is r e a d i l y w e t b y resins, a p o l y m e t h y l e n e spacer a l l o w i n g o u t w a r d o r i e n t a t i o n of t h e e x p o s e d g r o u p , a n d at the o p p o s i t e e n d a r e a c t i v e g r o u p c a p a b l e of c h e m i c a l l y b o n d i n g to the s o l i d substrate. M o r e t h a n one r e a c t i v e g r o u p i n t h e m o l e c u l e m a y b e d e s i r a b l e ; for e x a m p l e , w e h a v e i n v e s t i g a t e d t h e use of one or m o r e c a r b o x y l groups.
I n the case of t w o t e r m i n a l c a r b o x y l g r o u p s , t h e y s h o u l d
be
s e p a r a t e d b y m o r e t h a n one c a r b o n a t o m to a v o i d s e n s i t i v i t y to d e c a r boxylation.
Alternatively, the single c a r b o x y l group m a y be
with -SiCl , - S i ( O E t ) 3
QCX>
3
replaced
or other g r o u p s . CI
CI
0
-High surface energy group or
Strongly adsorbed group Figure 1.
Si(OEt)
C0 H 2
3
Structural concept for adhesion promoters
T h e present s t u d y o u t l i n e s m e t h o d s for p r e p a r i n g f o u r n e w m o n o c a r b o x y l i c a c i d s , t w o n e w d i c a r b o x y l i c a c i d s , together w i t h one k n o w n a n d t w o n e w s u b s t i t u t e d silanes. A l l c o m p l y w i t h t h e a b o v e s t r u c t u r a l concepts. S t r u c t u r e s of the six a c i d s are g i v e n b e l o w .
Monocarboxylic acids
Dicarboxylic acids CI
CI
(Ç 2)n-l H
C0 H 2
(Ç 2)n HC-CO«H I (ÇH,). 2'x I C0 H H
2
η = 12, 14, 18 and 20
2
η = 12 χ = 1 and 2 Alexander; Interaction of Liquids at Solid Substrates Advances in Chemistry; American Chemical Society: Washington, DC, 1968.
12
INTERACTION O F LIQUIDS A T SOLID SUBSTRATES
A l l six o f t h e c h l o r o p h e n y l - s u b s t i t u t e d c a r b o x y l i c acids a r e d e r i v e d f r o m a c i d c h l o r i d e s of l o n g - c h a i n a l i p h a t i c h a l f esters. T o p r e p a r e these uncommon
intermediates i n sufficient a m o u n t s , p r a c t i c a b l e p r e p a r a t i v e
m e t h o d s h a d to b e d e v e l o p e d .
M e t h o d s are g i v e n f o r c o n v e r t i n g a p p r o
p r i a t e α,ω-dicarboxylic acids t o the c o r r e s p o n d i n g a c i d c h l o r i d e h a l f esters. C e r t a i n o f t h e p - c h l o r o p h e n y l - s u b s t i t u t e d c a r b o x y l i c acids a r e r e l a t e d p r o d u c t s i n a m u l t i s t e p synthesis. A s c h e m a t i c o u t l i n e o f s y n t h e t i c p r o c e d u r e s is presented to c l a r i f y these r e l a t i o n s h i p s . P r o p e r t i e s o f seven new
p-chlorophenyl-substituted
intermediates
a n d six n e w p - c h l o r o
p h e n y l - s u b s t i t u t e d c a r b o x y l i c acids a r e r e p o r t e d .
A l l o f t h e 13 n e w
c o m p o u n d s h a v e b e e n c h a r a c t e r i z e d b y c o n v e n t i o n a l c r i t e r i a . B o t h gasliquid chromatography
a n d nuclear magnetic
resonance
are used to
assess t h e p u r i t y o f t h e c a r b o x y l i c acids a n d t h e i r i n t e r m e d i a t e s . Synthetic
Methods
α,ω-Dicarboxylic A c i d s .
DODECANEDIOC A N D OCTADECANEDIOC ACID.
T h e d o d e c a n e d i o c a c i d , m . p . 125°-127 ° C , w a s p u r c h a s e d f r o m A l d r i c h C h e m i c a l C o . , M i l w a u k e e , W i s c o n s i n . H u n i g s 1.6 g r a m p r e p a r a t i v e p r o c e d u r e f o r o c t a d e c a n e d i o c a c i d ( 6 ) w a s s c a l e d u p f o r 9 0 g r a m batches i n a c c o r d a n c e w i t h h i s l a r g e scale m e t h o d f o r d o c o s a n e d i o c a c i d ( 7 ) . R e c r y s t a l l i z a t i o n f r o m m e t h y l e t h y l ketone, gives o c t a d e c a n e d i o c a c i d (m.p. 1 2 1 ° - 1 2 4 ° C ; 5 7 % y i e l d ; 9 6 % p u r i t y ) . T h e p r i n c i p a l impurity is tridecanedioc acid. Diesters. D I E T H Y L DODECANEDIOATE AND D I E T H Y L OCTADECANEDIOATE.
T h e respective diesters w e r e p r e p a r e d i n 9 9 . 4 % a n d 9 9 . 0 % p u r i t i e s b y the m e t h o d r e p o r t e d f o r d i e t h y l a d i p a t e ( 9 ) . P h y s i c a l properties o b s e r v e d f o r t h e respective diesters agree w i t h r e p o r t e d values ( I , 2, 15). H a l f Esters.
E T H Y L HYDROGEN DODECANEDIOATEAND E T H Y L HYDRO
G E N O C T A D E C A N E D I O A T E . P r a c t i c a b l e m e t h o d s h a d to b e d e v e l o p e d f o r c o n v e r t i n g t h e d i e t h y l esters to t h e respective h a l f esters i n batches as large as 100 grams. T h e i m p r o v e d process gives a r e l a t i v e l y h i g h c o n v e r s i o n of t h e r e a c t e d diester t o t h e h a l f ester a n d a l l o w s a q u a n t i t a t i v e r e c o v e r y of t h e u n r e a c t e d diester w h i c h c a n b e s u b m i t t e d t o another batch operation. A l c o h o l i c s o d i u m h y d r o x i d e s o l u t i o n ( 2 6 m l . o f I N ) is a d d e d d r o p w i s e d u r i n g 3 0 m i n . to a s t i r r e d m i x t u r e o f d i e t h y l d o d e c a n e d i o a t e ( 15.0 g r a m s ; 0.0524 m o l e ) a n d e t h y l a l c o h o l ( 3 0 m l . ) . W a t e r ( 6 0 m l . ) is a d d e d a n d s t i r r i n g is c o n t i n u e d (ca. 15 m i n . ) u n t i l t h e p H reaches 8.0. E x t r a c t i o n of t h e aqueous m i x t u r e w i t h p e t r o l e u m ether ( 3 0 ° - 6 0 ° C . b o i l i n g r a n g e ; 2 X 120 m l . ) removes u n r e a c t e d d i e t h y l d o d e c a n e d i o a t e ( 8 . 6 0 g r a m s ; 0.0300 m o l e ) . A c i d i f i c a t i o n o f t h e aqueous l a y e r w i t h 600 m l . o f 0.1N hydrochloric acid precipitates ethyl hydrogen dodecanedioate a n d d o d e c a n e d i o c a c i d . B o t h acids are extracted w i t h ether ( 2 X 150 m l . ) . A f t e r d r y i n g a n d c o n c e n t r a t i n g t h e extract, the r e s i d u e is m e l t e d b y w a r m i n g t o 6 0 ° C , p o u r e d i n t o 250 m l . of p e t r o l e u m ether a n d a l l o w e d t o s t a n d for 1 h o u r at 25 ° C . f o r e q u i l i b r a t i o n . P r e c i p i t a t e d d o d e c a n e d i o c a c i d is r e m o v e d b y filtration (1.80 grams; 0.0078 m o l e ) . T h e filtrate is c o o l e d
Alexander; Interaction of Liquids at Solid Substrates Advances in Chemistry; American Chemical Society: Washington, DC, 1968.
2.
13
Adhesion Promoters
O'REAR E T A L .
t o —10 ° C . a n d filtered to collect t h e e t h y l h y d r o g e n d o d e c a n e d i o a t e , 3.72 g r a m s ; 0.0144 m o l e ; m.p. 4 9 ° - 5 0 ° C . i n agreement w i t h t h e ^reported v a l u e ( 8 ) . T h e y i e l d s b a s e d u p o n t h e a m o u n t of diester c o n s u m e d a r e 6 4 . 3 % h a l f ester a n d 3 4 . 8 % d i a c i d , a t o t a l of 9 9 . 1 % . Y i e l d s b a s e d u p o n the diester u s e d are 2 7 . 5 % h a l f ester, 1 4 . 9 % d i a c i d , a n d 5 7 . 3 % r e c o v e r e d diester, a t o t a l o f 9 9 . 7 % . D i e t h y l octadecanedioate c a n b e p r e p a r e d b y the same s t o i c h i o m e t r y p r o v i d e d that the diester is d i s s o l v e d i n f o u r times as m u c h a l c o h o l ( 4 X 30 m l . ) , that t h e s a p o n i f i c a t i o n step is p e r f o r m e d at 6 0 ° C , a n d t h a t t h e final m i x t u r e of d i a c i d a n d h a l f ester is r e s o l v e d i n hexane. T h e m o d i f i e d p r o c e d u r e y i e l d s e t h y l h y d r o g e n o c t a d e c a n e d i o a t e m e l t i n g at 71.5° t o 72.5°C. i n agreement w i t h t h e l i t e r a t u r e v a l u e ( I ) . Y i e l d s b a s e d u p o n the a m o u n t of diester c o n s u m e d a r e 9 0 . 0 % h a l f ester a n d 3 . 3 % d i a c i d . B a s e d u p o n t h e a m o u n t of diester u s e d , t h e y a r e 4 4 . 4 % h a l f ester, 1.6% d i a c i d a n d 5 1 . 0 % r e c o v e r e d diester. A c i d Chlorides of H a l f Esters. T h e h a l f esters a r e c o n v e r t e d to t h e c o r r e s p o n d i n g h a l f ester a c i d c h l o r i d e b y a l l o w i n g e a c h to s t a n d o v e r n i g h t w i t h t w o e q u i v a l e n t s of t h i o n y l c h l o r i d e . U n r e a c t e d t h i o n y l c h l o r i d e is r e m o v e d a t r e d u c e d pressure. T h e r e s i d u a l a c i d c h l o r i d e s are u s e d f o r the p r e p a r a t i o n o f t h e keto esters. Keto Esters.
ω - ( P - C H L O R O B E N Z O Y L ) ALKANOIC ACID ESTERS.
The in
t e r m e d i a t e keto esters, p - C l C H C O ( C H ) i C O E t a n d p - C l C H C O ( C H ) i C 0 E t , w e r e s y n t h e s i z e d f r o m α,ω-dicarboxylic acids via t h e m a j o r steps s h o w n i n S c h e m e I. 6
2
7
4
0
2
2
6
4
2
SCHEME I CI
CI
C0 H 2
(ÇH ) -2 2
n
C0 H 2
>(Ç 2)n-2
HÇH ) _
H
2
C0 Et
n
2
-
(CH ) 2
C0 Et
2
n - 1
C0 H
2
2
η = 12; η = 18
acid chloride
co-(chlorobenzoyl)
dicarboxylic acid
of half ester
alkanoic acid ester
ω-(chlorophenyl) alkanoic acid
A c i d c h l o r i d e s of t h e respective h a l f esters a r e c o n v e r t e d t o t h e d e s i r e d keto esters b y F r i e d e l - C r a f t s reactions r e s e m b l i n g those d e v e l o p e d b y F i e s e r f o r p r e p a r i n g t h e -(p-chlorobenzoyl)nonanoic a c i d ester ( 5 ) . T h e keto esters are c o n v e r t e d to the respective keto acids t h r o u g h s a p o n i fication w i t h 1 0 % a l c o h o l i c p o t a s s i u m h y d r o x i d e , a c i d i f i c a t i o n a n d r e c r y s t a l l i z a t i o n f r o m toluene. Y i e l d s of t h e keto acids b a s e d u p o n t h e respective a c i d c h l o r i d e s a r e 75 a n d 7 9 % . P r o p e r t i e s o f t h e keto a c i d s a n d t h e i r d e r i v a t i v e s a r e g i v e n i n T a b l e s I a n d II. Monocarboxylic
Acids,
ω- ( P - C H L O R O P H E N Y L ) A L K A N O I C ACIDS.
The
saturated acids p - C l C H 4 ( C H ) C 0 H a n d p - C l C H ( C H ) i C 0 H of S c h e m e I result f r o m the W o l f f - K i s h n e r r e d u c t i o n (4) o f t h e c o r r e s p o n d i n g ω - ( p - c h l o r o b e n z o y l ) a l k a n o i c acids. R e s p e c t i v e y i e l d s of t h e acids 6
2
1 1
2
6
4
2
7
Alexander; Interaction of Liquids at Solid Substrates Advances in Chemistry; American Chemical Society: Washington, DC, 1968.
2
14
INTERACTION O F LIQUIDS A T SOLID SUBSTRATES
Table I.
No.
Analysis and Properties of Intermediates B.P. (°C./mm. Hg)
Compound
1. p - C l C H C O ( C H ) C O H 2. p - C l C H C O ( C H ) C 0 H 3. p - C l C H ( C H ) O H 4. p - C l C H ( C H ) O H 5. p - C l C H ( C H ) B r 6. p-ClC H (CrL>) Br 7. p - C l C H ( C H ) C H ( C 0 E t ) C 0 E t 6
4
6
2
4
6
4
2
1 2
6
4
2
1 8
6
4
6
1 0
2
2
4
2
199/1.0 210/1.0 — 245/1.5
1 2
4
2
1 2
2
2
N.E. Calcd. Found 324.0 409.9
105-107 324.9 110-112 409.0 32-34 58-60
2
1 6
18
6
M.P. CC.)
44-46 —
— —
Analyses (%) Cl
H Calcd. Found
Cahd. Found
CigHosClOa C H C10 Ci H C10 C H C10 C H BrCl
66.55 70.48 72.82 75.65 60.09
66.56 70.53 72.83 76.05 59.55
7.66 9.12 9.85 10.86 7.85
7.66 9.21 10.02 10.98 7.80
6. C H o B r C l
64.93
64.50
9.08
9.02
7. 0 5 Η
68.39
68.49
8.95
8.90
No . 1. 2. 3. 4. 5.
Formula
2 4
3 7
8
2 9
2 4
3
4 1
1 8
2 8
24
4
Calcd.
Found
10.91 8.67 11.94 9.31 9.85 22.21° 7.99 18.00 8.08
10.86 8.83 11.95 8.90 9.85 21.17° 8.46 18.85° 8.00
a
2
a
00
3 9
4
Bromine assays.
Table II.
Analysis and Properties of Carboxylic Acids
No. 8. 9. 10. 11. 12. 13.
M.P. (°C.)
Compound p-ClC H (CH ) C0 H p-ClC H (CH ) C0 H P-C1C H (CH ) C0 H p-ClC H (CH ) COoH p - C l C H ( C H ) C H ( COoH ) CH CO>H p - C l C H ( C H ) C H ( C 0 H ) CHoCHC0 H 6
4
6
2
4
6
2
4
6
2
4
2
n
2
1 3
9
1 7
2
1 9
6
4
2
1 2
6
4
2
1 2
9
2
2
67-68 70-70.5 74-75 78-79 87-88 85-86
N.E. Calcd. Found 310.9 337.4 395.0 423.1 198.5 205.5
313.0 338.9 396.0 424.0 198.9 206.7
Analyses (%)
No.
Formula
8.
CigH C10
9.
C*>QH JC10O
10. 11. 12. 13.
27
2
3
C C C C
24
H C10Ô H C10 H C10 H C10 39
2 6
4 3
2
2 2
3 3
4
2 3
3 5
4
Η
CI
Calcd. Found
Calcd. Found
Calcd. Found
69.55 70.88 72.97 73.81 66.57 67.22
8.75 9.22 9.95 10.24 8.38 8.58
69.68 70.65 73.26 73.83 66.60 67.52
8.80 9.31 10.26 10.31 8.40 8.63
11.41 10.46 8.98 8.38 8.93 8.63
Alexander; Interaction of Liquids at Solid Substrates Advances in Chemistry; American Chemical Society: Washington, DC, 1968.
11.65 10.37 8.61 8.31 8.88 8.56
2.
O'REAR E T A L .
15
Adhesion Promoters
after w o r k - u p a n d r e c r y s t a l l i z a t i o n f r o m h e p t a n e (—10 ° C . ) a m o u n t to 80 a n d 9 5 % . T h e other h o m o l o g o u s a c i d s , p - C l C H ( C H ) i 3 C 0 H a n d p - C l C e H ( C H ) i 9 C 0 2 H are derived from appropriate monoalkylated m a l o n i c esters s h o w n i n S c h e m e I I t h r o u g h s a p o n i f i c a t i o n , a c i d i f i c a t i o n , and decarboxylation. e
4
4
2
2
2
S C H E M E II CI > (ÇH2)
(ÇH )n-l 2
C 0
2
(ÇH ) 2
n
2
N
H C - C 0
HC-C0 Et
Br
H
(ÇH )
n
2
C0 Et
(ÇH ) 2
2
C 0
Side r e a c t i o n
2
2
H
X
H
η = 12 χ = 1; χ = 2
(ÇH ) 2
C 0
2
n +
l
H
η = 1 2 ; η = 18 Alcohols.
O>-(P-CHLOROPHENYL)DODECYL A L C O H O L A N D «>-(p-CHLORO-
P H E N Y L ) ocTADECYL A L C O H O L . T h e s e alcohols are o b t a i n e d i n greater t h a n 9 5 % y i e l d s f r o m L i A l H r e d u c t i o n s of t h e a p p r o p r i a t e m o n o c a r b o x y l i c acids. 4
Bromides,
ω- ( P - C H L O R O P H E N Y L ) D O D E C Y L B R O M I D E A N D ω- ( P - C H L O R O -
P H E N Y L ) OCTADECYL BROMIDE.
Conversion
of
the
alcohol
to
the
corre
s p o n d i n g b r o m i d e is a c c o m p l i s h e d b y C o l l i n s ' m e t h o d ( 3 ) . T h e respec tive bromides are purified b y distillation i n 8 4 % y i e l d , a n d b y recrystal lization from alcohol i n 7 8 % yield. Monoalkylated Malonic A c i d Esters. D I E T H Y L ω-( P - C H L O R O P H E N Y L ) DODECYLMALONATE
AND DIETHYL
ω- ( p - C H L O R O P H E N Y L ) O C T A D E C Y L M A L O -
N A T E . T h e s e i n t e r m e d i a t e diesters of S c h e m e I I are p r e p a r e d b y r e a c t i o n of s o d i o d i e t h y l m a l o n a t e (0.30 m o l e ) a n d t h e a p p r o p r i a t e
