PREPARATION OF SUBSTITUTED STYRENES
Aug., 1944
1295
TABLE I PHYSICAL CONSTANTS AND
ANALYTICALDATA Analyses, Calcd.
B. p. or m. p., "C.
Cornpourid
B-Py~-idyI-methylamine~~ Picrate1aJ4 3-(a-Aminoethyl)-pyridinel+
112 (18 mm.) 210-211 dec. 223 (740 mm.) 112-113 (22 mm.) Phenylthiourea 139-140 280 dec. Chloroplatinate 204-205 Picrate Di- (8-pyridylmethyl) -amine 147-148 (mm.) Chloroplatinate >300 Picrate 2 18-220 152-153 (1 mm.) [ Di-a,af-(3-pyridyl) ]-diethylamine Chloroplatinate 292, 161-163 Picrate 205 dec. Oxime of 2,4-dimethyl-3-acetyl-5-cart~ethoxypyr19i-198 role Oxime of 2,4-dimethyl-4-carbethosy-5-acetylpyr162-163 role Monoxime of 2,4-dimethyl-3,5-diacetylpyrrole 240 dec. 2,~-Dimethyl-3-vinyl-5-carbethoxypyrrole 110.5-112 Benzoate of 2,4-dimethyl-3-(a-arninoethyl)-5-carbethoxypyrrole 179-180 149-150 Benzoate of 2-( e-aminoethyl)-pyrrole 159-1 60 2,4-Dirnethyl-3-~cetyl-5-ethylpyrrole 2,4-l~imethyl-3-carbethosy-5-ethylpyrrole 106-10'7 186-187 Ethyl 8-(3-pyridyl)-acrylatehydrochloride
a picrate, m . p. 210-211" dec., a dihydrochloride, 111. p. 222', and a p-nitrobenzoate, m. p. 188-189". The picrate of the secondary amine had a m. p. of 218-220". Ethyl nicotinoacetate (30 9.) took up 1 mole of hydrogen pcr mole of ester a t 85' within two and one-half hours. Fractional distillation of the product gave 11 g. of a compound, b. p. 136-138" (3 mm.), believed to he /3-(3-pyridyl)acrylic ester. The ester polymerized so rapidly that within twenty-four hours the refractive index had fallen from 1.5518 to 1.4612; however, a stable hydrochloride, m . p. 185-186'. was obtained.
[CONTRIBUTION FROM
THE
%
Found
S , 25.93
2(i.00
N, 22.95
23.12
h7, 16.34 Pts36.68 N,:. 19.31 N, 21.11 Pt, 35.96 N, 18.96.
16.29 36.66 19.46 20.81 35.68 18.80
Pt, 34.76 N, 18.38
34.61 18.50
N, 12.50
12.-17
N, 12.50 N, 14.43 N, 7 . 2 5
12. fiB 14.08 7.57
8.92
9.01 12.91 8.58 7.38 56.35 5.78 16.62
S,
N, 13.08 K,
8.48 7.18 c, 56.20 H, 5.62 C1, 16.65
N,
Summary The hydrogenations over Raney nickel of eight oximino, keto and cyano derivatives of pyrrole and pyridine have been described. (13) Craig and Hixon, THISJOURNAL, 68, 4369 (1931). (14) Erlenmeyer and Epprecht, H&. Ckim. A d a . 10, (i!)O
(1937).
MADISON, WISCONSIN
RECEIVED J U X E 16, 1911
RESEARCH LABORATORY OF SPRAGUE ELECTRIC Co. ]
Preparation of Substituted Styrenes BY LESTERA. BROOKS Our interest in a study of the electrical characteristics of .the polymers of various halogen substituted styrenes has necessitated the preparation of the corresponding monomers. Since the results of the electrical measurements are not complete and will be reported in a later paper, we are describing the preparation of several monomeric styrene derivatives at this time. A knowledge of ihe electrical properties of materials is of value in the communications field and considerable work has been reported on .various organic compounds.'82.3However, i t appears that (1) White and Bishop, THISJOURNAL, 61, 8 (1940) (2) White, Biggs and Morgan, tbrd 69, 10 (1'140)
little investigation has been made of specific styrene derivatives. A modification of the styrene molecule accomplished by the introduction of a halogen atom in the ring will raise the dielectric constant. Any advantage due to increased dielectric constant will be nullified if a correspondingly large increase in dielectric loss occurs, or if the resulting polymer is not chemically stable in an electric field. I t is well known t h a t many iodine compounds are thermally unstable even a t moderate temperatures. Bromine compounds also show this behavior but to a less extent, as, for example, in the case of the isomeric polybrom~styrenes.~
LESTER-A. BROOKS
12Oti
The discoloration produced 0x1 aging may be attributed t o the liberation of bromine. This bromine liberation would be intensified by an electric field and the bromine would be in a form which would result in high dielectric loss. In the case of non-polymeric materials, McLean and co-workers have shown tbat common commercial dielectrics such as chlorinated diphenyl eventually liberate hydrogen chloride in an electric field. This effect would probably be much smaller than that which would occur in the corresponding brominated diphenyl. It seemed, therefore, that thermal and electrical stabilities, as determined by dielectric loss measurements, would be higher in polyfluorostyrenes than in polychlorostyrenes. The following compounds are, described for the first time with the exception of m-chlorostyrene and P-chlorostyene, These two chlorostyrenes have recently been reported; they were prepared by methods different from those which have been used i i i this work. The monomers were prepared by the batch dehydration of the carbinols using not over i".C: of fused potassium bisulfate in conjunction with suitable pressures. In this manner excellent yields of the corresponding styrenes were obtained. The crtrbiiiols mere prepared by reduction of tlie corresponding ketone or by addition of a Grignaril reagent to an aldehyde. When the styrenes were purified by repeated distillation, polymerization occurred more readily. The dichlorostyrenes were least stable in this respect and the fluorostyrenes most stable. The lessened stability of the chlorostyrenes might be attributed to the presence of traces of hydrogen chloride. An analogous situation would be unlikely in the case of the fluorostyrenes. Experimental6 suspension of iiict hylniagnrsiirni i)roniije was prrpared hv hubhling co~i~riic~cial mer hyl hrotiiidc. into 1-liter of anhydrous ether which covered 2G.7 g. of iiiagrirsiurn turni.igs.. When thc Iiiagiic.;iuni was almost dissolved 140 g . of redistilled eomincrcial o-chlorobenzaldehydc, dissolved in ,500 cc. of anhydrous ether, v a s added dropwise with stirring. The rraction miuture was then worked LID iii the usual manner. l ' h c vield >.vas1 I!) g . (7G' ;'I of a coldrless liquid, b. p. 10810!lc ( 7 n i i i i . ) ; d'?; 1.355: R?"D l.tj4,5i , ~ l n u l . Calcd. for CkH90Cl:C , fi1,ij-l; 14, 5.75. Found c, 60.80; 1-1, 5.w o-Chlorostyrem-In a ,?OO-cc. modified Claisen flask were placed 3f)O g. of n-chlorophenyImethylcarhino1, 2 g. ( 1 ',;) of powdered, fused potassium bisulfate, and 2 g. of hydroquinone. The flask wan immersed in a n oil-bath heated to 200-210°, and the pressure was adjusted to 110130 m i n l'hc styrcnc, water and rarbinol distilied a t 125llOo iri about oiic and one-half to two hours. The disc tillntc. WAF dissolved in ether. The ether solution was washr:l with 5'; sodium hydroxide, !hen with a saturated calciurn ch!oride solution, and finally dried over calcium chloride Aftcr renroval of the ether 81 g. ( 7 0 : ; ) of o-
o-Chlorophenylmethy1carbinol.-A
.~ .
(r))
AlcLean. bqtlrton. Kohman and Brotherton, l ? t d . E n g . Chem.,
34, i n 1 i i c ) ~ . IC)! \'ields of s t y r e n e s arc b a w l n n t h e unrecovered carhinols. >Jicrixin.~lyscc hy h l r R o y a l . I
