INDUSTRIAL AND ENGINEERING CHEMISTRY
2552
and Sisman for reactor radiation ( 9 ) . Complete loss of strength occurred in the reactor after exposure estimated to be 50,000,000 r. of gamma, plus beta and neutron irradiation. I n these experiments with gamma alone, complete failure occurred a t 100,000,000 to 200,000,000 r., indicating that beta and neutron irradiation as well as gamma are harmful. It is worth noting that and ( 6 )found Some materials-e.g*, Were unchanged in strength after prolonged radiation. Consequently the data reported here on physical properties must be considered specific for the materials studied. CONCLUSIONS
It was concluded that: when polymonochlorotrifluoroethylene (Fluorothene) and polyvinyl chloride are exposed to gamma radiation, the quantities of halogen evolved may be significant from corrosion and contamination viewpoints, For engineering DurDoses, the rate of evolution can be taken as 7 millimoles of halide per gram of material per billion roentgens of exposure.
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Polyvinyl chloride retained physical strength better than polymonochlorotrifluoroethyleneduring exposure to gamma radiation. ACKNOWLEDGMENT
The authors wish to express appreciation to Carbide & Carbon Chemicals Co. for making available the facilities and materials for this study. Personal thanks are given to C. D. Watson of the Oak Ridge National Laboratory for his guidance and aid. REFERENCES
(1) Burton, M., J . Phys. & Colloid Chem., 51, 786 (1947). ( 2 ) Gisman, O., and Bopp, C. D., "Physical Properties of Irradiated Plastics," R e p t . ORNL-928, p. 9, Oak Ridge National Laboratory, Carbide and Carbon Chemicals Co., 1951. (Copies available a t Depository Libraries of t h e iitomic Energy Commission.) (3) Ibid., P. 85. (4) p s 166. (5) Watson, C. D., personal communication (April 1952).
I
RECEIYED for review january 21, 1953.
ACCEPTED
July 15, 1053.
Large-Scale Laboratory Preparation of 2,5-Dichlorostyrene HENRY POLLOCK AND H. W. DAVIS Department of Chemistry, University of South Carolina, Columbia, S . C .
E
RICKSON and Michalek (7) prepared 2,5-dichlorostyrene
by means of the side-chain chlorination of 2,5-dichloroethylbensene followed by dehydrochlorination. Dehydrochlorination of l-chloroethyl-2,5-dichlorobenzeneby means of steam and calcium sulfate to produce the desired styrene has been reported by Basdekis ( 9 ) . Another method ( 5 ) utilized the simultaneous reduction and dehydration of 2,5-dichloroacetophenone in the presence of ethyl alcohol and silica gel. Brooks ( 3 , 4 ) prepared thia dichlorostyrene by the synthesis of 2,5-dichlorobenzaldehyde from 2-chloro-5-nitrobenzaldehyde and treatment with methylmagnesium bromide to give the corresponding carbinol which was dehydrated over potassium acid sulfate. The crtrbinol has been dehydrated by Michalek ( 1 1 ) over hot alumina a t reduced pressure. A survey of analogous reactions that had possibilities for application to this problem showed that Walling and Wolfstirn (14) had prepared 3,Pdichlorostyrene from the decarboxylation of 3,4-dichlorocinnamic acid. Marvel et al. (10) prepared the acetate of 3,4-dichlorophenylmethylcarbinol,which produced the corresponding styrene on pyrolysis. Overberger and Saunders ( I d ) treated 3-chlorophenylmagnesium bromide with acetaldehyde to produce the carbinol, which was dehydrated over potassium acid sulfate to yield rn-chlorostyrene. Procedures were selected for study on the basis of availability and cost of starting materials, ease of synthesis, and equipment required, excluding a t once those involving dehydrohalogenation of a side-chain halogen. Although the initial over-all yield for reaction 1, about 16%, waa low as compared to 34% for reaction 2, and 35'% for reaction 3, i t was decided to investigate further the preparation of 2,5dichloroacetophenone because of the simplicity of synthesis leading to the corresponding styrene. Several acetylations of p-dichlorobenzene gave the data of Tables I and 11.
The results indicated that it was necessary to acetylate in a n excess of p-dichlorobenzene, since the conventional solvents used for preparations of this type proved unsatisfactory. A comparison of the reactivities of acetyl bromide and acetyl chloride shows no difference within the limit,s of experimental error. It mas necessary to use a large excess of aluminum chloride, probably because of the formation of an aluminum chloride complex with the ketone. The over-all yields of 2,5-dichlorostyrene for the procedures in Figure 1are given below: % Yield
Procedure Experimental
1 2 3 4 6
43 34
35 0 19
Literature . t .
... 51
...
...
Thus the most suitable of the above schemes for the preparation of 2,5-dichlorostyrene, based on the over-all yield and simplicity of synthesis, consists of the acetylation of p-dichlorobenzene and its reduction to the carbinol, followed by dehydration over activated alumina. EXPERIMENTAL
Procedure 1. ACETYLATION. Acetyl chloride (6.13 moles, 480 grams) is added dropwise for 20 minutes, with stirring, to a mixture of 12.25 moles (1630 grams) of aluminum chloride in 17.5 moles (2570 grams) of molten p-dichlorobenzene and a t a temperature of 70" C. The p-dichlorobenzene is dried previously by distillation at atmospheric pressure. The temperature is raised to 100" C . when addition is complete, and the mixture is heated with continued stirring for 3 hours, or until the evolution of hydrogen chloride is slight. The reaction mass is cooled to
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INDUSTRIAL AND ENGINEERING CHEMISTRY
moved by distillation over a steam bath, and the yellow oil 2,5-Dichloroacetophenone that remains is distilled at Yield, % 104' C. at 1-mm. pressure to Based on Moles of Acyl Acetic unrecovered Based on Recovered Reaction produce an 8401, yield of p-DichloroHalide Anhyp-diohloro- acyl halide p-DiohloroTemp., 2,5-dichlorophenylmethylcarbenzene Moles' dride AlCla benzene used benzene c. binol with a melting point of 0 0.95 46" 1 .o 2.0 0 100-110 0 2.0 0.90 0 1.0 62' to 63' C. 0.90 100-110 0 2.0 0 1.0 23 0.45 100-1 10 39 ... 1.0 DEHYDRATION. The cata100-110 0.51 39 19.5 ... 1.0 lytic dehydration is carried out 100-110 17.1 0.53 27.5 0.5 1.5 100-110 37.0 21.4 0.42 1.2 ... at a pressure of 100 mm. in a 100-110 36.5 20.4 0.44 1.2 ... 100-110 0.92 1.0 0 ... 0 25-mm. inside diameter elec140' 1.0 0 0 0.00 ... trically heated b o r o s i l i c a t e 100-11o;e 1 .o a 0.96 0 ... 100-110 0.51 ... 1.0 37 18.1 glass tube containing 40 om. 100-1 10 8 0.92 0 0 1.0 1.0 0.47 1.0 35 16.5 100-110 ... of alumina pellets (Alumina 100-110 0.45 1.0 34 ... 18.7 Catalyst AI - 0501 T I/s', 100-110 0.52 0.70 53 73 100-110 0.51 48.5 67 0.70 Harshaw Chemical Co.) and 0.53 100-110 35.8 0.70 48 9.5 100-110 67 51.3 12.25 heated to 300" t o 325". Carbon disulfide solvent. The melted carbinol, con* Acetyl Nitrobenzene solvent. chloride taining 0.2% tert-butyl catechol Acetyl bromide'. as a polymerization inhibitor, Dry hydrogen chloride added before aoetylation. is added dropwise to the alumina a t a rate of 50 t o TABLE 11. LITERATURE SEARCH ON ACETYLATION OF DICHLOROBENZENES 60 ml. per hour. The yellow Aoetyl Reaction Chloride, DichloroAlCla, Ketone Ttrnz., brown liquid is washed with benzene Mole Mole Yield, yo Investigators water and dried over anhym-Dichlorobenzene, 1.0 I .o 40 100-110 Roberts and Turner 1.U mole $8) drous calcium chloride. The o-Dichlorobenzene, 1.0 1 .O 15 100-110 Ro erts and Turner dry product is then flash dis1 0 mole (13) p-Dichlorobenzene, 0.635 0.60 27 100-1 10 deCrauw (6) tilled over a Wood's metal 0.58 mole p-Dichlorobenzene Excess Excess 60 100-110 Kshatriya Shodhan, bath a t 140' C. through a 2 X and Na;gund (8) 20 cm. helices-packed column a t 3-mm. pressure. The waterwhite liquid is then treated with 75" C., poured slowly with stirring over 20 kg. of ice to which has 8570 ethyl alcohol, in the ratio of 75 ml. of ethyl alcohol solution been added 3 liters of concentrated hydrochloric acid, and then per 100 ml. of styrene, by stirring rapidly for 2 hours. The ethyl is allowed to stand overnight. The organic layer is extracted alcohol layer is then removed and discarded, and the styrene is with 3 liters of carbon tetrachloride and washed with several porwashed with several portions of cold water to remove the ethyl tions of cold water. The wet carbon tetrachloride and excess alcohol. The wet product is then treated with 5% sodium hyp-dichlorobenzeneare removed by distillation a t atmospheric presdroxide to remove the inhibitor, washed with water, and dried sure up to a temperature of 175' C. The residue is allowed to over anhydrous calcium chloride for 1 hour. This gives a maxicool to 100" C. and distilled over a 2 X 20 mm. helices-packed mum freezing point of 7.32" C., indicating a purity of 96.85%. fractionating column to produce 4.08 moles (772 grams) of 2,5The average yield of 2,5-dichlorostyrene is 85y0. dichloroacetophenone boiling a t 106" C. a t 5-mm. pressure. and Procedure 2. DIAZOTIZATION. According to the method of with a refractive index of 1.5600g. This is 67% of the theoretideCrauw (6) 80 grams (0.5 mole) of 2,5-dichloroaniline was cal yield. Nine and one-half moles of p-dichlorobenzene were diazotized in the presence of sulfuric acid and treated with potasrecovered. sium iodide solution. The product yield after recovery and REDUCTION.This is done according to the method of Lund purification was 92.5 grams (68%) of 2,5-dichloroiodobenzene, boilingat 250" (752 mm.); 122' (8 mm.). (9). A mixture of 5 moles (945 grams) of 2,5-dichloroacetophenone, 5 moles (1020 grams) of aluminum isopropoxide, and 5 liters of dry isopropyl alcohol is placed in B one-neck round(I) (2) bottomed flask equipped with CI C I a cold finger-type distilling I head a s diagrammed by Arndt (2 ). The flask is heated in a boiling water bath for 6 hours, during which time acetone and most of the isopropyl alcohol are removed by distillation. The residue is cooled in an ice bath and acidified with CH3MqBr Cu;Qulnoline 6 liters of 10% hydrochloric acid. The mixture is then extracted with 5 liters of benU C O O H (4) HNOz zene, washed with water and maton;tt p) ( y o CUCl2 CI 5y0 sodium bicarbonate, and "I' "2 dried over anhydrous calcium chloride. The benzene is reFigure 1. Selected Methods for Synthesis of 2,5-Dichlorostyrene
TABLE I. ACETYLATIONS OF p-DICHLOROBENZENE
O
d
*
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0". 8
-%$?+
ocHoOGL 0 ~
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INDUSTRIAL AND ENGINEERING CHEMISTRY
GRIGNARD SYNTHESIS. Following the method used by Overberger and Saunders (12) in the preparation of 3-chlorophenylmagnesium bromide, 2,5-dichlorophenylmagnesium iodide was prepared using 68 grams (0.25 mole) of 2,5-dichloroiodobenxene and 6.1 grams (0.25 mole) of magnesium ribbon in anhydrous ether. This was treated with acetaldehyde in the usual manner t o produce upon purification 30 grams (62.5%) of 2,5-dichlorophenylmethylcarbinol. This reaction is of interest in view of the difficulty frequently encountered in the formation of Grignard reagents from dichloro compounds having a chlorine adjacent t o the active halogen. DEHYDRATION. The method used was the same as in Procedure 1 to given an 85% yield upon dehydration and an over-all yield of about 35y0. Procedure 3. The 2,5-dichlorostyrene was prepared in the manner used by Brooks (3). The over-all yield was 34 to 35%, somenvhat higher than that given in the literature for this procedure. This is accounted for by the higher yield in dehydrating the carbinol over alumina rather than with potassium acid sulfate. Procedure 4. The 2,5-dichlorocinnamic acid was prepared in 94y0 yield using the method of Walling and Wolfstirn (IC). Successive attempts to decarboxylate the acid did not produce sufficient material to afford purification and identification. Procedure 5. BROMINATION AND ESTERIFICATION. Bromine (96 grams; 0.60 mole) was added to 105 grams (0.60 mole) of 2,5-dichloroethylbenzene in carbon tetrachloride. The product was isolated but not purified. The mixture of CY- and 8-bromoethyl-2,5-dichlorobenzene was treated with fused potassium acetate in acetic anhydride by the method of Marvel et al. (10). This produced a 63% yield of 1-(2,5-dichlorobenzene)-ethylacetate, boiling at 124’ to 127’ (7 mm.) and having the following physical
Vol. 45, No. 11
constants: n g 1.5242; d;: 1.2353. Molecular refraction: theoretical 57.89; found 57.34. PYROLYSIS. The pyrolysis was performed by dropping the ester through a vertical column containing glass beads that was heated to 425’ to 450’. tert-Butyl catechol was used as an inhibitor. The yield was 31% of the theoretical and gave an overall yield for 2,5-dichloroiodobenzeiie of 19%. LITERATURE CITED
Arndt, F., Org. Sgntheses, 20,27 (1940). Basdekis, C. H. (to Monsanto Chemical Co.), U. S. Patent 2,485,524 (Oct. 18,1949). Brooks. L. A.. J. Am. Chem. SOC..66. 1295 (1944). Brooks; L. A:, and Nazzewski, Matihew (to SGague Electric Co.), U. S. Patent2,406,319 (Aug. 27, 1946). Carbide & Carbon Chemicals Corp., Brit. Patent 1316,844 (Jan. 27,1949). de Crauw T., Rec. trav. chim., 51, 757 (1931). Erickson. E. R.. and Michalek, J. C. (to Mathieson Alkali Works, Inc.), U. S. Patent 2,432,737 (Dec. 16, 1947). Kshatriya, K. C., Shodhan, N. S., and Nargund, K. S., J . Indian Chem. SOC.,24,373 (1947). Lund, H., Ber., 70, 1520 (1937). Marvel, D. S., Overberger, C. G., Allen, R. E., Johnston, 1%. W., Saunders, J. H., and Young, J. E., 6.Am. Chem. SOC., 68,863 (1946). Michalek, J. C. (to Nathieson Alkali Works), Brit. Patent 564,828 (Oot. 16, 1944). Overberger, C. G., Saunders, J. H., Allen, R. E., and Gander, R., Org. Syntheses, 28,28-31 (1946). Roberts, E., and Turner, E. E., J Chem. Soc., 1927, 1855. Walling, C., and Wolfstirn, L. B., J . Am. Chem. SOC.,69, 852-4 (1947). RECEIVED for review April
1 5 , 1953. A C C E P T E D July 23, 1953. Presented at Southeastern Regional hfeeting, AMERICANCHENICAI, SocmrY, Auburn, Ala., October 25, 1952. Performed under Contract CST-1020, Ordnance Division, National Bureau of Standards, Washington, D. C.
Aeration Studies on Propa ation of Baker’s Yeast WILLIAM D. ilIAXON AND MARVIN J. JOHNSOS University of Wisconsin, Madison, Wis.
T
HE study of the transfer of oxygen from the air into liquid
cultures of microorganisms has been greatly stimulated in recent years by the increased industrial importance of aerobic submerged culture fermentations such as are used in large-scale production of antibiotics. The influence of air throughput rate, agitator power and speed as well as fermentation vessel, agitator, sparger, and baffle design upon the absorption of oxygen has been investigated by many workera in several different manners. Thorough investigations of the oxygen uptake rates of tsodium sulfite solutions in fermentation-type vessels under various conditions were made by Cooper, Fernstrom, and Miller (3). Data of this sort have value for the empirical evaluation of the aeration effectiveness of fermentation equipment but are limited by the physical dissimilarities between the liquid phase in such an aqueous system and that in an actual fermentation. Karow el al. ( I f ) have described the use of such data for fermentor design. Bartholomew et al. ( 8 ) and Wise ($8) have made direct studies of aeration in penicillin and streptomycin fermentations using polarographic measurements of oxygen concentration in the medium. Similar experiments have been carried out by Hixson and Gaden (9) in the submerged propagation of bakers’ yeast. The system chosen for the present study was the aerobic
propagation of the baker’s yesst organism, Saccharomyces cerevisiae. It is ideal in the following ways: 1. The organism grows well on a conipletely synthetic medium with glucose as the sole source of carbon.
2. The over-all metabolism of the organism is simple. The only major products are yeast cells, ethanol, and carbon dioxide. 3. The process requires air. The absence of air causes an easily measured change in metabolism, the increased rate of formation of ethanol. 4. The organism is enzymatically stable and is relatively easy t o keep free of contaminating microorganisms, There are three general methods for the propagation of haker’s yeast. When the complete growth medium is initially charged (a batch fermentation), the sugar is partially glycolized to ethanol, and the remainder is oxidized to carbon dioxide. Recent studies of this type of yeast propagation have been made by Swanson and Clifton ( 1 7 ) . I n order to provide a more economical conversion of sugar to cellular material, it is common practice to limit the rate of supply of sugar to the point where the yeast is able to convert i t completely to carbon dioxide. The usual means to this end is the addition of glucose a t exponentially increasing rates to a growing yeast culture-a slow feed fermentation. This is the type of
