CCV1.- T7ze Action of Phosphorus Pentachloride on the Methylene Ethem of Catechol Derivatives

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RARGER : CYCLIC CAHRONATES. 2081 Published on 01 January 1908. Downloaded by Freie Universitaet Berlin 9/27/2018 8:26:04 PM.

CCV1.- T7ze Action of Phosphorus Pentachloride on the Methylene Ethem of Catechol Derivatives. Payt 111. The Cyclic Carbonates of Dichloro-ethyl- and -pyopyl-ca techol. By GEORGEBARQER. SOMEyears ago, in conjunction with Dr. €1. A. D. Jowett, the author made an attempt to convert ap-dibromo-a-3 : 4-methylenedioxyphenyl- ethane, CB2<0>~,;I~3.C€IBr*CHzBr0 (Trans, 1905, 87,967), iiito the View Article Online 2082 BARGER : THE ACTION OF PHOSPHORUS PENTACHLORIDE

corresponding catechol derivative by Fittig and Remsen’s reaction. The only product which could be isolated was a small qnantity of a dibromohydrin, CH,:O,:C,H,Br*CH(OH).CH,Br, formed by the action of bromine which had been liberated by the phosphorus pentn- chloride. When the subject was again taken up more recently, an attempt was made to use thionyl chloride instead of phosphorus pentachloride, for, as the author has shown (Trans., 1908, 93, 563), the former reagent converts cntechol methylene ethers directly into cyclic carbonates. In the present case, however, the reaction proceeded in an anomalous manner, and instead of the desired Substance, a thio- naphthen derivative was formed, as described in the next paper (p. 2086). After this failure, recourse wc.3 again had to phosphorus pent’achloride, and, in order to exclude the secondary action of liberated bromine, the dibromide previously employed was replaced by the corresponding dichloride. This substance, CH2<~>C,H,*CHC1*CH2Cl, was rciidily prepared from the corresponding styrene, but as it could only be obtained as a viscid oil, it was found convenient to convert it into the crystalline chlorohydrin, CH2C,H,*CH(OH)*CH2Cl, which is easily obtained pure. On submitting the chlorohydrin to the action of three molecular proportions of phosphorus pentachloride, it is reconverted into the dichloride and then transformed into a dichloromethylene derivative, C~~2~6~3*~H~~*~~~~~.0 The latter substance not only distils without decomposition, but, unlike the known examples of this unstable type, it can be obtained crystalline. By treatment with anhydrous formic acid, the cyclic carbonate, Published on 01 January 1908. Downloaded by Freie Universitaet Berlin 9/27/2018 8:26:04 PM.

results, which is a derivative of 3 : 4-dihydroxy-l-ethylbenzene,prepared by Delange (Compt. rend., 1904, 138, 423). The preparation of the corresponding dibromide, CO<~>C6~~*CHBr*CH,Br,was recently attempted unsuccessfully by Pltuly and Neukam (Bw.,1907, 40, 3488) by the addition of bromine to vinylcatechol carbonate. From the easily obtainable isosafrole dichloride, by successive treatment with phosphorus pentachloride and formic acid, the cyclic carbonate, COC,H,*CHCl*CHCl*CH,,0 was prepared ; it closely resembling its lower homologue. By boiling water, both carbonates are readily hydrolysed to catechol compounds, but, in addition, the a-chlorine atom is removed. So far it has not been possible to isolate the chlorohydrin, C6H3(HO),*CH(OH)*CH,Cl; it would appear that, View Article Online ON THE METHYLENE ETHERS OF CATECHOL DERIVATIVES. 2083

under the conditions hitherto employed, hydrogen chloride is eliminated and a chlorovinyl derivative is formed. Further experiments are, however, in progress.

EXPERIMEN T AL. ap-Dichtom-a-3 1 ,-.4-metl~yler~edioxyphenyZethane,

To 15 grams o€ 3 : 4-methylenedioxystyrene (Klages, Ber., 1903, 36, 3505), dissolved in carbon tetrachloride, a solution of chlorine in the same solvent was added until a sample no longer decolorised a dilute solution of bromine. On distillation, 16 grams of the crude dichloride passed over at 160-lSOo/16 mm. It constituted a viscid liquid, which could not be crystallised. As it could not readily be purified by fractional distillation, it was converted into the chlorohydrin (described below), and this was reconverted into the dichloride by heating on the water-bath with thionyl chloride. The regenerated dichloride then boiled at 159-160°/12 mm., and was not quite pure, as shown by the analysis : 0.1475 gave 0.1837 A.gC1. C1= 30.8. C,H,O,CI, requires C1= 32.4 per cent. There would appear to be a tendency to lose hydrogen chloride.

/3-Chloro-a-hycEroxya-31 4-)72etiLyEenediox~~~Leny~et~La~~e, ?-<-)cH (OH) .CH,~ CH,* 0- Published on 01 January 1908. Downloaded by Freie Universitaet Berlin 9/27/2018 8:26:04 PM. This chloroliydrin was prepared by leaving the crude dichloride (above) for one day, dissolved in a mixture of acetone and water (compare Auwers and Miller, Ber,, 1902, 35, 114), or, preferably, by heating the solution in aqueous acetone with powdered marble, on the muter-bath under a reflux condenser. After removal of the acetone and water by distillation, the partly solid residue was pzessed on a porous plate and crystallised from a mixture of light petroleum and benzene, when it formed long needles melting at 95' and boiling at 169-1 7Oop mm. : 0.1398 gave 0.2756 CO, and 0.0560 H,O. C = 63.8 ; 11: = 4.4. 0.2023 ,, 0.1474 AgCl. C1= 18.0 C,H,O,Cl requires C = 53.9 ; H = 4.5 ; C1= 17.7 per cent. The yield of this substance and the preceding one was much inferior to that of the corresponding dibromide and bromohydrin. View Article Online 2084 BARUER : THE ACTION OF PHOSPHORUS PENTACHLORIDE

ap-Dicldoro-a-3 ; 4-dichZoromethylenedioxyphenyZethne, g-C13Cl*CH2Cl. C12*0 The dichloride and chlorohydrin were heated respectively with two and three molecular proportions of phosphorus pentachloride to 150-170° for four hours. The flask mas provided with a Young's still-head, 60 as to allow the phosphorus trichloride and oxychloride to distil over, but to retain the pentachloride. At the end of the reaction, a small quantity of phosphorus pentachloride was sublimed out of the flask under diminished pressure, and the contents were then distilled under a pressure not exceeding 10 mm. Under suitable conditions, the yield is almost quantitative ; thus, for instance, 5 grams of the chlorohydrin, heated with 15.7 grams of phosphorus pentachloride to 150" for six hours, yielded 6.5 grams of a distillate boiling at 170-174'/6 mm. (the thooretical yield is '7.1 grams). On one occasion, during a severe frost, the distillate, which was left overnight in the receiver., solidified; it was pressed on a porous tile, arid could then be crystallised from light petroleum and benzene, yielding prisms which melted at 56". Later crystallisation could never be produced spontaneously, but only by inoculation : 0.1758 gave 0.2536 CO, and 0.0372 H,O. C = 39.3 ; H = 2.3. 0.1632 ,, 0.3206 AgC1. C1= 48.6. . C,H60,Cl, requires C = 39-6 ; H = 2.1 ; C1= 49.3 per cent. The crystals fume in moiet air and gradually liquefy ; when dissolved in acetone, the substance reacts violently with water, the temperature oE the acetone being raised to the boiling point. With anhydrous formic acid fumes of hydrogen chloride are rapidly evolved without Published on 01 January 1908. Downloaded by Freie Universitaet Berlin 9/27/2018 8:26:04 PM. much heat, and the cyclic carbonate is formed.

ap-Dich lor0 - a- 3 : 4-carbon y Zdioxyplbenylet ham, /- p-( )CHCI*CH,CI. GO-0- Anhydrous foitmic (or acetic) acid is added carefully in small yuan- tities to the dichloromethylene derivative described above, and the excess is removed by distillation under diminished pressure. This completes the reaction, and the carbonate can then be distilled. It boils at 180-182°/8 mm.," the yield being quantitative. A fraction b. p. lSZ0/8 mm. was analysed: * At, or about, this prevsure the cyclic catecliol carbonates generally boil loo highcr than the dichloronicthylene derivatives, froui which they are obtained. View Article Online ON THE METHYLENE ETHERS OF CATECHOL DERlVATIVES. 2085

0.1573 gave 0.2624 CO, and 0.0390 H20. C = 46.2 j H = 2.7. 0.1842 ,, 0.2275 AgCl. C1= 30.5. C,H,03CI, requires C = 46.4 ; H = 2.6 ; C1= 30.5 per cent. Although the analysis proves the substance to be quite pure, it could not be crystallised. At the room temperature, it is a very viscid oil, readily soluble in all ordinary organic solvents, except light petroleum. When boiled with water, it dissolves gradually, being converted into a cstechol derivative, but at tlie same time a large amount of a dark brown resin is formed.

ap-Dicldoi*o-a-3: 4-dichloromethyZened ioxgphenylpropane, ?--

Published on 01 January 1908. Downloaded by Freie Universitaet Berlin 9/27/2018 8:26:04 PM. ap-Dichloro-a- 3 : 4-~arbonyZdioxyphenytpropa?~e, 1-\ y<-)CHGl* CHCl*CH,, coo0 After treatment of the previous substance with formic acid, the carbonate is obtained as a viscid oil, b. p. 186-189"/8 mm., closely resembling the lower homologue : 0.1760 gave 0.3111 GO, and 0*0532 H20. C = 48.2 ; II = 3.3. 0.2240 ,, 0.2687 AgCl. C1= 28.7. C,,H,O,CI, requires C = 48.6 ; H = 3.2 ; C1= 28.7 per cent. THE WELLCOYEPHYSIOLOGICAL RESEARCH LABORATORIES, BROCKWELL HALL, HERNEHILL, LONDON, s. E.