w a s p a s s e d t h e s p e c i f i c conductivity i n c r e a s e d a g a i n with i n c r e a s i n g hydrogen ion concentration.
ACKNOWLEDGMENT T h e authors are grateful for t h e many helpful s u g g e s t i o n s and c o n s t r u c t i v e criticism offered by Delwin D. Blue, Boulder C i t y Station, and by Harry C. F u l l e r , M a n g a n e s e Section. To t h e s e and t o many o t h e r s not mentioned but who contributed indirectly, t h e authors e x p r e s s t h e i r appreciation.
LITERATURE C I T E D (1) Harned, H. S., Owen, B. B., ACS Monograph S e r i e s , No. 9 5 , pp. 137-8, Reinhold, N e w York, 1943. (2) International Critical T a b l e s , vol. VI, p. 236, McGraw-Hill, N e w York, 1929. (3) Mellor, J. W . , “Comprehensive T r e a t i s e on Inorganic and T h e oretical Chemistry,” v o l . 11, p. 670, Longmans, Green, N e w York, 1941. (4) Stender, W. W., Seerak, I. J., T r a n s . Electrochem. S O C . 68, 4 9 5 (1935). R e c e i v e d for r e v i e w August 16, 1956. 1957.
Accepted February 20,
Solubility of Acrylonitrile in Aqueous Bases and Alkali Salts ELIAS KLEIN, J. W. WEAVER, AND BEVERLY G. WESRE Southern Regional Research Laboratory, New Orleans, La.
D u r i n g a study of t h e reaction i n which cotton c e l l u l o s e w a s c y a n o e t h y l a t e d with acrylonitrile u s i n g a q u e o u s a l k a l i b a s e s a s c a t a l y s t s , t h e s o l u b i l i t y of acrylonitrile i n a q u e o u s s y s t e m s w a s required. S i n c e t h e liquid p h a s e a s s o c i a t e d most intimately with t h e cotton c e l l u l o s e during t h e reaction i s a dilute a q u e o u s solution of sodium hydroxi d e or other b a s e , t h e solubility of t h e acrylonitrile i n t h i s p h a s e w a s believed t o b e a determining factor in both t h e r a t e of t h e reaction and t h e e x t e n t of cyanoethylation a t equilibrium. T h e solubility of acrylonitrile in water h a s been reported for various temperatures ( I ) , but no solubility d a t a for acrylonitrile i n v a r i o u s a l k a l i a n d s a l i n e s o l u t i o n s could b e found.
MATERIALS USED T h e acrylonitrile w a s of commercial grade, containing
0.8% of water. In order t o f a c i l i t a t e reading of t h e i n t e r f a c e with
a q u e o u s l a y e r s t h e acrylonitrile w a s colored with
0.005% Celliton F a s t R e d GGA Ex. Conc. (Pr. 236).
(Pr.
2 3 6 refers t o t h e prototype d y e number l i s t e d in t h e AATCC Yearbook for 1955.) All a l k a l i hydroxides and s a l t s were of reagent grade, e x c e p t Naxonate G , a commercially availa b l e mixture of xylene s u l f o n a t e s .
PROCEDURE B e c a u s e acrylonitrile r e a c t s with water i n t h e p r e s e n c e cf b a s e s , i t w a s n e c e s s a r y t o use a solubility determination procedure not b a s e d on equilibrium measurements. T h e measurements were carried o u t a t 2 5 ” i 1 C. i n a n a i r bath. T h e t e c h n i q u e s employed a r e e s s e n t i a l l y t h o s e reported by Booth a n d E v e r s o n ( 2 ) i n their study of hydrotropic s a l t s . In t h e procedure adopted, 4 5 m l . of v a r i o u s conc e n t r a t i o n s of a l k a l i b a s e s w e r e weighed into stoppered, graduated sulfonation b o t t l e s (ASTM D 875-46T); a m e a s -
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INDUSTRIAL AND ENGINEERING CHEMISTRY
ured volume of acrylonitrile w a s then added rapidly, and t h e b o t t l e s were s e a l e d and tumbled end over end. Thirty minutes a f t e r t h e addition of acrylonitrile t h e tumbling w a s stopped and t h e volume remaining w a s read on t h e gradua t e d s c a l e of t h e bottle. Thereafter readings were t a k e n every 15 minutes until t h e residual acrylonitrile w a s less than 1.0 ml. T h e c h a n g e i n t h e volume of acrylonitrile w a s d u e t o two c a u s e s . T h e f i r s t , a rapid c h a n g e complete in less than 30 minutes, w a s d u e to t h e solution of t h e acrylonitrile in t h e a q u e o u s p h a s e . T h e s e c o n d , a n d slower change, w a s due to t h e hydration of acrylonitrile t o e t h y l e n e cyanohydrin. A s t h e a q u e o u s p h a s e w a s s a t u r a t e d with r e s p e c t t o acrylonitrile during t h e e n t i r e measurement period, a n d t h e b a s e concentration remained e s s e n t i a l l y unchanged, t h e r a t e of acrylonitrile hydration w a s evidently z e r o order. A plot of t h e volume of acrylonitrile remaining vs. time w a s found t o b e linear. Extrapolation of t h i s plot t o zero time permitted a correction t o b e made for t h e l o s s of acrylonitrile d u e t o reaction, and yielded t h e volume of acrylonitrile d i s s o l v e d i n t h e a q u e o u s phase. Use of t h e density of t h e acrylonit r i l e and t h e known weight of water i n t h e flask allowed calculation of t h e molality of acrylonitrile i n t h e a q u e o u s phase. When both a l k a l i b a s e s and s a l t s were p r e s e n t simultaneously, t h e s a m e procedure w a s followed. T h e a q u e o u s b a s e w a s weighed into t h e f l a s k s , a n d w e i g h t s of t h e s a l t c a l c u l a t e d t o give a c o n s t a n t molality of s a l t solution w e r e added. When t h e solubility of acrylonitrile w a s determined i n s a l t s o l u t i o n s alone, t h e previous method w a s not n e c e s sary. Weighed amounts of s a l t s o l u t i o n s were p l a c e d i n t h e f l a s k s and increments of acrylonitrile were added until a s e c o n d p h a s e persisted. T h e s o l u t i o n s were tumbled for 30 minutes between a d d i t i o n s of acrylonitrile. VOL. 2, NO. I
centrifuge t u b e s a n d a d d i n g a q u e o u s sodium iodide solut i o n s until a n a q u e o u s l a y e r separated. T h e refractive i n d i c e s of a l l t h e s a t u r a t e d s o l u t i o n s were determined with a n Abbk refractometer; t h e s e d a t a were l a t e r u s e d for e s t a b l i s h i n g t h e direction of t h e t i e lines. P o i n t F , representing t h e solubility of sodium i o d i d e i n t h e acrylonitrile, w a s determined u s i n g t h e method of Vaughn and Nutting ( 4 ) . T h e point is not q u i t e on t h e sodium iodide-acrylonitrile b a s e l i n e , b e c a u s e of t h e p r e s e n c e of 0.8% of water in t h e acrylonitrile, a n d a t r a c e of w a t e r in t h e sodium iodide.
RESULTS AND DISCUSSION F i g u r e 1 s h o w s t h e s o l u b i l i t y of acrylonitrile, e x p r e s s e d a s moles of acrylonitrile p e r 1000 grams of water, a s a function of t h e weight per c e n t of sodium hydroxide i n t h e solution. If t h e solubility of acrylonitrile i s plotted a g a i n s t t h e s q u a r e root of t h e sodium hydroxide molality, t h e relationship i s linear. Addition of hydrotropic s a l t s (3)-i,e., 2.l
i1.5 W
0.5
\
t
\
s L
4
a W
3
g
1.c
v, 0
5 10 NoOH CONCENTRATION, WT. %
I5
0 U
>
t
Figure 1. Solubility o f acrylonitrile in aqueous sodium hydroxide, aqueous sodium hydroxide and sodium benzoate (1.5 molal), and aqueous sodium hydroxide and sodium iodide (2.0 molal) a t 2 5 O c.
4 0
05
T h e determination of t h e ternary solubility diagram of sodium iodide, water, a n d acrylonitrile required a combination of methods. P h a s e boundary AC (Figure 5) w a s determined by weighing sodium i o d i d e s o l u t i o n s i n t o t h e sulfonation b o t t l e s a n d a d d i n g i n c r e m e n t s of acrylonitrile until t h e s e c o n d p h a s e p e r s i s t e d a f t e r tumbling. P h a s e boundary DE w a s determined by weighing acrylonitrile into graduated oil
0
IO S4LT
20 CONCENTR4TION,WT. X
30
Figure 2. Solubility o f acrylonitrile i n various concentrations of sodium chloride, sodium iodide, sodium benzoate, and sodium xylene sulfanates a t 2 5 O C.
1957
40
0
2
4 6 L i O H CONCENTRATION, WT. %
8
Figure 3. Solubility o f acrylonitrile i n aqueous lithium hydroxide, and aqueous lithium hydroxide and sodium iodide (2.0 molal) a t 2 5 O C .
s a l t s which i n c r e a s e t h e s o l u b i l i t y of organic s o l u t e s in water, s u c h a s sodium i o d i d e or sodium benzoate-inc r e a s e s t h e solubility of acrylonitrile in t h e sodium hydroxi d e s o l u t i o n s . T h i s i n c r e a s e in solubility, however, h o l d s only over a limited range of sodium hydroxide concentrations. With sodium iodide, t h e hydrotropic e f f e c t p r e v a i l s up t o 1.8% sodium hydroxide concentration; with sodium b e n z o a t e t h e e f f e c t e x t e n d s t o 6.5%. Above t h e s e b a s e concentrations t h e salt effect becomes additive and the acrylonitrile i s “ s a l t e d out” more rapidly than if only t h e b a s e were present. T h e hydrotropic e f f e c t of s e v e r a l s a l t s on t h e s o l u b i l i t y of acrylonitrile i n w a t e r c a n b e s e e n from F i g u r e 2. T h e solubility of acrylonitrile, given in molal units, i s plotted a g a i n s t t h e weight per c e n t of t h e s a l t s i n t h e a q u e o u s solutions. Sodium c h l o r i d e i s a l s o shown, t o i l l u s t r a t e t h e s a l t i n g out effect. Of t h e t h r e e hydrotropic s a l t s shown, t h e mixed sodium xylene s u l f o n a t e s a r e t h e most efficacious. While t h e d a t a for t h e l a t t e r compounds a r e not CHEMICAL AND ENGINEERING D A T A SERIES
73
1.7
I .5
w
=' k
s V U
1.0 n
3 VI
E LL
0
>
t
3 05 I
0
3
6
9
12
K O H CONCENTRATION ,WT. %
Figure 4. Solubility o f acrylonitrile i n aqueous potassium hydroxide, and aqueous potossium hydroxide and sodium iodide (2.0 m o l a l ) a t 25' C.
shown here, they i n c r e a s e t h e solubility of acrylonitrile in a q u e o u s sodium hydroxide, when t h e s o h u m hydroxide c o n c e n t r a t i o n s a r e below 9%. Other s a l t s which showed hydrotropic e f f e c t s with acrylonitrile were potassium iodide, sodium s a l y c i l a t e , a n d potassium thiocyanate. No hydrotropic e f f e c t s were shown by t h e sodium s a l t s of 1,3,6-naphthalenetrisulfonica c i d , '$,5-naphthalell~disulfonic a c i d , a n d s u l f o s a l y c i l i c a c i d (data not shown here). F i g u r e s 3 and 4 show t h e solubility of acrylonitrile in a q u e o u s lithium and potassium hydroxide, r e s p e c t i v e l y , and i n t h e s a m e s o l u t i o n s made 2.0 molal with r e s p e c t t o sodium iodide. In t h e c a s e of lithium hydroxide t h e point a t which t h e hydrotropic effect c e a s e s to function i s 1.5%; in that of potassium hydroxide t h e corresponding point i s a t 0.4%. A comparison of t h e solubility of acrylonitrile in t h e three alkali hydroxides s h o w s that t h e s a l t i n g out effect, due t o t h e b a s e s alone, i s s t r o n g e s t with lithium hydroxide a n d w e a k e s t with potassium hydroxide. T h i s comparison i s valid, a l s o , when t h e c o n c e n t r a t i o n s a r e compared on a molality b a s i s . A comparison of F i g u r e s 1 a n d 2 i n d i c a t e s that t h e concentration of sodium hyrdoxide a t which hydrotropy c e a s e s d e p e n d s on t h e e f f i c a c y of t h e hydrotropic s a l t . T h i s s u g g e s t s t h a t t h e greater t h e hydrotropic effect of t h e s a l t in water, t h e greater will b e t h e range of b a s e concentration over which t h e e f f e c t will prevail. F i g u r e 5 d e p i c t s t h e ternary solubility diagram of sodium iodide, water, and acrylonitrile. T h i s s y s t e m w a s investigated with t h e h o p e t h a t i t might s h e d some light on t h e mechanism by which t h e i n c r e a s e d solubility of acrylonitrile w a s obtained. Sodium iodide w a s chosen a s t h e s a l t b e c a u s e of i t s ease of handling and t h e simplicity of t h e hydrate diagram. L i n e AC d e s i g n a t e s t h e solubility of acrylonitrile in water with i n c r e a s i n g sodium iodide concentrations. T h e a r e a e n c l o s e d by ACE a n d t h e b a s e l i n e s r e p r e s e n t s a homogeneous solution of t h e t h r e e
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INDUSTRIAL AND ENGINEERING CHEMISTRY
components. L i n e BC d e l i n e a t e s t h e solubility of sodium iodide in water containing i n c r e a s i n g amounts of acrylonitrile. L i n e DE d e l i n e a t e s t h e solubility of water i n acrylonitrile with i n c r e a s i n g sodium iodide content of t h e organic phase. L i n e EF s h o w s t h e solubility of sodium iodide in acrylonitrile containing varying amounts of water. An initial composition falling i n t h e a r e a E-F-sodium iodide vertex s e p a r a t e s i n t o two p h a s e s : a s o l i d sodium iodide p h a s e and a n acrylonitrile p h a s e s a t u r a t e d with sodium iodide. An initial composition falling in t h e a r e a E-C-G-sodium iodide s e p a r a t e s into three p h a s e s cons i s t i n g of NaI or NaI.H,O, a n a q u e o u s p h a s e of composition C, and an organic p h a s e of composition E. T h e position of t h e p h a s e transition between anhydrous sodium iodide and i t s monohydrate w a s not determined b e c a u s e of t h e experimental d i f f i c u l t i e s involved. However, when acrylonitrile w a s a d d e d t o a mixture of sodium iodide a n d water having a composition l y i n g along segment BG, t h e first a p p e a r a n c e of an o r g a n i c p h a s e occurred a t a composition lying on l i n e GC; t h i s i n d i c a t e s that s a t u r a t e d a q u e o u s s o l u t i o n s of composition E C a r e i n equilibrium with NaI.H,O d e s p i t e t h e p r e s e n c e of acrylonitrile i n t h e aqueous phase. P h a s e boundaries AC and D E show t h a t acrylonitrile i s s a l t e d into water d u e to t h e p r e s e n c e of sodium iodide, but that water i s s a l t e d out of acrylonitrile by t h e p r e s e n c e of sodium iodide.
CONCLUSIONS T h e solubility of acrylonitrile in water i s d e c r e a s e d by t h e p r e s e n c e of a l k a l i b a s e s . T h i s lower solubility c a n b e compensated for i n d i l u t e b a s e s o l u t i o n s by t h e addition of hydrotropic s a l t s , s u c h a s sodium iodide, sodium benzoa t e , and sodium xylenesulfonate. T h e range of b a s e c o n c e n t r a t i o n s over which a given hydrotropic s a l t c a n e x e r t i t s influence a p p e a r s t o b e proportional t o i t s hydrotropic e f f e c t i v e n e s s i n t h e a b s e n c e of t h e b a s e . T h e r e a p p e a r s t o b e no d e f i n i t e method for predicting whether or not a given s a l t will h a v e hydrotropic effect on s o l u t i o n s of acrylonitrile, However, a s m a l l but f i n i t e solubility of t h e s a l t i n acrylonitrile a p p e a r s t o b e required. T h e c o n v e r s e of t h i s s t a t e m e n t i s not n e c e s s a r i l y true: Dioxane i s s o l u b l e in acrylonitrile, but i t s addition, i n
F i g u r e 5. Ternary solubility diagram of sodium iodide, water, and acrylonitrile a t 25 C., weight per cent
VOL. 2, NO. I
LITERATURE CITED
H. S., E v e r s o n , H. E . , Znd. Eng. Chem. 40, 1491 (1948). (3) McBain, M. E. L., Hutchinson, E., “Solubilization and Related Phenomena,” Chap. 6, Academic P r e s s , New York, 1955. (4) Vaughn, T. H., Nutting, E. G., Jr., Ind, E n g Chem., A n a l . E d . 14, 4 5 4 (1942).
(1) American Cyanamid C o . , Synthetic Organic C h e m i c a l s Dept., “Chemistry of Acrylonitrile,” Cyanamid’s Nitrogen Chemic a l s D i g e s t 5, (1951).
R e c e i v e d for review May 18, 1956. A c c e p t e d August 2 5 , 1456. Mention of trade names d o e s not imply endorsement by the Department of Agriculture over similar competitive products.
amounts up to lo%, to a s a t u r a t e d a q u e o u s s o l u t i o n of acrylonitrile will c a u s e t h e s e p a r a t i o n of an acrylonitrile phase.
(2) Booth,
Viscosities of Fluorinated Methyl Bromides and Chlorides JOHN F. REED AND B. S. RABINOVITCH Department of Chemistry, Loyola University, Chicago, Ill., and Department of Chemistry, University of Washington, Seattle, Wash.
I n studying t h e c h e m i c a l r e a c t i o n s of t h e fluorinated methyl c h l o r i d e s and bromides with sodium vapor, i t w a s n e c e s s a r y t o o b t a i n t h e v i s c o s i t i e s of t h e s e h a l i d e s . Very few d a t a o n t h e v i s c o s i t i e s of t h e s e compounds a r e recorded; t h e v a l u e s that e x i s t h a v e b e e n obtained by independent m e a s u r e m e n t s and provide no opportunity for internal comparison or c o n s i s t e n c y .
EXPERIMENTAL
T a b l e I. V i s c o s i t i e s and Molecular Diameters of G a s e s
77, Exptl. ( 2 5 ° C . ) , a
n Lit. ( 2 5 ‘C.),
Micropoises
Micropoises
Compound
[ 107.9 (0. l)] CH,C1 107.9 (1) 113.1 ( 0 . 7 ) CFH,Cl 129.2 ( I ) CF,HCl 139.6 (0.7) CF,Cl 134.8 ( 0 . 1 ) 135.2 (2) CHSBr 129.1 (0.4) CFH,Br 140.4 (0.1) CF,HBr 151.2 ( 0 . 2 ) CF,Br =Probable error of average g i v e n in parentheses.
...
... ... ...
... ...
Diameter, A. 5.55 5.85 5.81 5.85 5.81 6.10 6-18
T h e fluorinated chloro compounds were o b t a i n e d from t h e K i n e t i c C h e m i c a l s Division, E. I. d u P o n t d e Nemours b Co. Methyl c h l o r i d e a n d bromide were E a s t m a n Kodak white l a b e l products. T h e fluorinated bromo compounds were a l l s y n t h e s i z e d by u s i n g t h e Hunsdiecker degradation of t h e s i l v e r or sodium s a l t of t h e corresponding carboxylic a c i d by bromine. All compounds were d i s t i l l e d s e v e r a l t i m e s on a low temperature fractionating column and only t h e middle f r a c t i o n s of c o n s t a n t boiling r a n g e were e m ployed. M a s s s p e c t r a l p a t t e r n s w e r e obtained for a l l compounds and s h o w e d t h e a b s e n c e of a p p r e c i a b l e impurities. T h e coefficient of v i s c o s i t y w a s determined by allowing t h e s p e c i m e n g a s to flow from a 2-liter bulb through a uniform g l a s s c a p i l l a r y a t room temperature into a n e v a c u a t e d b o r o s i l i c a t e g l a s s t r a p refrigerated by liquid nitrogen. T h e i n i t i a l and final p r e s s u r e s i n t h e bulb were measured, a s well a s t h e e l a p s e d time. T h e c o l l e c t e d c o n d e n s a t e w a s transferred t o a tared e v a c u a t e d g a s bulb and weighed. S a m p l e s were 100 t o 300 mg. and required c o l l e c t i o n t i m e s were 1 to 3 hours. T h e p r e s s u r e s in t h e l a r g e bufb were 2 t o 15 cm. and n o correction for s l i p w a s n e c e s s a r y . T h r e e t o s e v e n d e t e r m i n a t i o n s w e r e made on e a c h sample. T h e maximum error w a s in t h e weighing, which had a precision within 1%.
T h e coefficient of v i s c o s i t y i n c r e a s e s gradually with i n c r e a s e in t h e number of fluorine a t o m s in t h e molecule for t h e c h l o r i d e s , although a minimum o c c u r s i n t h e bromide s e r i e s , T h i s may b e c o n s i d e r e d a c o n s e q u e n c e of t h e relat i v e i n c r e a s e i n molecular m a s s and molecular diameter, on p a s s i n g down t h e two s e r i e s . In view of t h e general lack of transport q u a n t i t i e s of g a s e s , o n e or more of t h e s e q u a n t i t i e s must often b e e s t i mated. When insufficient d a t a a r e a v a i l a b l e for c o r r e l a t i o n s b a s e d on structural f e a t u r e s , t h e k i n e t i c theory of g a s e s i s often u s e d . However, e v e n in t h e l a t t e r c a s e , a structural parameter, s u c h a s a c o l l i s i o n diameter, i s n e c e s s a r y . T h e c o l l i s i o n diameter of e a c h of t h e s e m o l e c u l e s w a s calculated from t h e v i s c o s i t y coefficient on t h e b a s i s of t h e hard, e l a s t i c s p h e r e approximation ( T a b l e I). Substitution of o n e fluorine atom in t h e molecule r e s u l t s in an i n c r e a s e in diameter, and s u c c e s s i v e s u b s t i t u t i o n s of fluorine c a u s e no further increment. T h i s behavior i s c o n s i s t e n t with t h e view of t h e s i m p l e , hard s p h e r e model.
RESULTS
ACKNOWLEDGMENT
T h e procedure w a s c a l i b r a t e d u s i n g methyl chloride, for which t h e v a l u e of t h e a b s o l u t e v i s c o s i t y of Renning and Markwood ( 1 ) w a s adopted. A l l m e a s u r e m e n t s were adj u s t e d t o 2 5 o C., u s i n g temperature c o e f f i c i e n t s of 0.3 and 0.6 micropoise per d e g r e e for t h e c h l o r i d e s and bromides, r e s p e c t i v e l y , b a s e d on t h e methyl compounds. T h e s e corr e c t i o n s were of t h e order of magnitude of t h e probable error of a s i n g l e measurement. T h e r e s u l t s a r e given i n T a b l e I, with l i t e r a t u r e v a l u e s .
T h e a u t h o r s thank G. H. Cady for h i s cooperation and t h e K i n e t i c C h e m i c a l s Division of t h e Du P o n t Co. for i t s gene r o u s gift. T h i s work w a s supported by t h e Office of Naval Research.
1957
6.15
DI SCUSSl ON
LITERATURE CITED (1) Benning, A. F., Markwood, W. H., Refrig. Eng. 37, 2 4 3 (1939). (2) Titani, T., B u l l . Chem. SOC.J a p a n 5, 9 9 (1930). R e c e i v e d for r e v i e w September 8, 1956. A c c e p t e d February 4 , 1957.
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