1706
NOTES
Reaction of 4-Methyldioxolone-2 with Aqueous Ethylamine MANUELM. BAIZER,JOHNR. CLARK,AND ERICSMITH
VOL.
22
CHART 11 CH3CHCHiOH
I
benzyl chloride
KOH
+
OH CH&HCH20CHzC6H5,purified4
I
Received April 16, 1957
OH
4
1. COCh 2. EtNHt
Najer et a1.l have reported that 4-methyldioxolone-2 (I;the cyclic carbonate of propylene glycol) reacts with 33% ethylamine to give exclusively the N-ethyl carbamate of the secondary alcohol group (11) and none of its structural isomer (111). They based their conclusions on the fact that they isolated and identified l-ethylamino-2-propanol (IV) upon degrading their carbamate according to the scheme shown in Chart I.
I1
Ha
tCHaCHCHzOCH2CsH5 Pd/C I
OCONHEt
The product was distilled through a four-inch Widmer-type column. It all boiled a t 99-100'/0.5-0.6 mm. The ng of several arbitrary cuts varied from 1.4512 to 1.4518. The phenylurethane melted at 83.8-85.0'. Compound I11 was prepared by treating propylCHARTI ene glycol with a deficiency of phosgene6 in benzene followed by reaction of the intermediate chlorocarCHI-CH-CHZ EtNHi bonate with ethylamine. The entire product, disI I 0 0 tilled through a small Widmer column, boiled a t \c/ 99"/0.4 mm.; ng 1.4548; m.p. of phenylurethane, II 95.S96.4'. 0 I The material (V) prepared according to the procedure of Najer et a1.I was distilled through a 55CHICH-CH~OH CH&HCHzOCONHEt I cm. helix-packed column. After a small forerun, I OCONHEt OH which was discarded, the product boiled at 92'/ I1 I11 0.3 mm.; ng 1.4510. The phenylurethane melted SOClt at 69-79' and could not be further purified by reCH3CH-CH2CI CH3CHCHzOCONHEt crystallizations. This melting point spread suggested that V was a mixture of carbamates which I I OCONHEt c1 had not been separated by the attempted fractional distillation. This conclusion was borne out by the A NaOEt infrared study of 11,111,and V. CHaCHCHzNHEt CHsCHCHzOH Whereas I1 and I11 have bands at 9.25 p and 9.5 I I p respectively, the relative extinction of I11 is the OH NHEt same at both wave lengths while I1 has a stronger IV absorption band at 9.5 p than a t 9.25 p. I11 has a strong band at 9.75 p which is shifted to 10.0 p in Since we have shown in another case2that this type the case of I1 and a band at 10.37 p absent in 11. of structure proof is unreliable because a rearrange- Mixtures of I1 and I11 may be quantitatively anament occurs during the thionyl chloride reaction: lyzed by measuring the extinction in methylene and since our experience has been that dioxolones chloride against methylene chloride in the blank react with ammonia to give mixtures of carbam- cell a t 9.25 p and 9.5 p. The French product V was ates3 in which the primary carbamate predomi- analyzed in this way against I1 and 1116as standards and was found to consist of approximately nates, we reinvestigated the French work. Compound I1 was prepared by the sequence out- 30y0 of I1 and 7oy0 of 111. The $hilarity of this distribution of isomers to that obtained from the lined in Chart 11: reaction of 4-(o-methoxyphenoxy)dioxolone-2 with alcoholic ammonia2is striking.
4
I
( 1 ) H. Najer, P. Chabrier, and R. Giudicelli, Bull. SOC. ch&. France, 1142 (1954). ' ( 2 ) M. M.Baizer. J. 9. Clark. and J. Swidinskv. J . 070. Ch&., 22, 1595 (1957). (3) J. D. Malkemus. U.S. Rat. 2,627,524, February 3. 1953 states w-ithout presenting proof that the reaction of higher unsymmetrical analogs of ethylene carbonate with ammonia probably yields ~ x t u r e sof structurally iso-
(4) C. L. Butler, A. G. Renfren, and M. Clapp, J . Am. Chern. Soc., 60, 1472 (1938). (5) The assumption is made that reaction occurs preferentially a t the primary alcohol group. Cf.Ref. ( 2 ) for a discussion of the confirmation of this assumption. (6; It is possible that o w sample of I11 contained a trace of I1 as an impurity, since the infrared spectrum of 111 shows 2. small shoulder at 10.00-10.05 fi in which region I1 has a
meric hydroxyalkyl carbamates.
strong absorption band.
"
I
DECEMBER 1957
NOTES
1707
solution of 49.5 g. (0.5 mole) of phosgene in 250 ml. of benzene. Stirring was continued for another hour a t about 30". Then a solution of 61 g. (0.5 mole) of dimethylaniline in 200 ml. of dry benzene was added a t an internal temperature of 25'. The mixture was stirred an additional 30 min., cooled to 5' and washed with 200 ml. of cold 20% sodium chloride, CHa-CH-CHz-GI 5% hydrochloric acid in 100 ml. of saturated salt solution, OCONHEt and finally two 100-ml. portions of cold 20% salt solution. VI The benzene solution was then added with stirring in the course of 20 min. to 250 ml. of 33% ethylamine a t 5-7". the basis of analogy with previous findings.2 This Stirring was continued in the cold for 2 hr. and thereafter the mixture allowed to stand in the refrigerator for 64 hr. formulation is consistent with the results obtained Fractionation through a Cinch spiral packed column of the by Najer et a1.l on further degradation and again residue remaining after the removal of the benzene yielded indicates that in the chlorination of an or-hydroxy- 2.27 g. of product? b.p. 99'/0.4 mm., ny 1.4548. Anal. Calcd. for Clif&&03: C, 48.98; H, 8.83; N, 9.52. carbamate there is a rearrangement, where needed, Found: C, 49.62; H, 9.03; N, 10.09. t o produce the 1-chloro-derivative. The phenylurethane, prepared as above, melted a t 95.296.4". Anal. Calcd. for C1aHlsNa04: C, 58.63; H, 6.81; N, 10.52. EXPERIMENTAI? Found: C, 58.92; H, 6.57; N, 10.51. A mixture of the phenylurethane of 111 and the phenyli-Benzyloxy-&(N-ethylcarbamoxy) propane. 1-Benzyloxy2-propanol was prepared according to Butler et al. Purifica- urethane of I1 melted a t 70-83". Product of Najer et al.1 (V). The crude product prepared tion of the crude by treatment with phthalic anhydride was included. The product boiled a t 126-128'/11-12 mm.; ny from 204 g. propylene glycol and 272 g. of 33% ethylamine 1.5112. To a stirred solution at 3O of 54.5 g. (0.55 mole) of according to the procedure of the French authors was fracphosgene in 250 ml. of dry toluene was added in the course tionated through a 55-cm. column packed with glass helices. of 60 min. a solution of 83 g. (0.5 mole) of l-benzyloxy-2- After a small forerun (24 g.) the entire remaining product propanol and 72.5 g. (0.6 mole) of dimethylaniline in 200 boiled a t 92'/0.3 mm.lO Each of 15 arbitrary cuts had ny 1.4510. The main fraction together with refractionated foreml. of dry toluene. The temperature was maintained a t 0-5' by external cooling with ice-salt during another hour of stir- run and heel yielded a total of 270.4 g. (92%) of product. Anal. Calcd. for CeHlsOaN: C, 48.98; H, 8.83; N, 9.52. ring. The mixture was then washed with ice water, 40 ml. of 5% hydrochloric acid, and two 50-ml. portions of ice water. Found: C, 49.54; H, 9.11; N, 10.10. The crude phenylurethane, prepared as above, melted a t The washed chloroformate solution was stirred in an ice-salt bath and 184 g. (1.35 moles) of 33% ethylamine was 66-86". Two recrystallizations raised the m.p. to 69-79", added in 20 min. a t an internal temperature below 15'. The unchanged by further recrystallizations. Reaetion of the carbamates I I , III, V with thionyl chloride. mixture' was stirred one more hour in the cold and one hour a t room temperature, then washed with three 100-ml. por- The procedure used with V is typical. V (14.7 g., 0.1 mole) tions of water. The toluene was stripped from the organic was well stirred while 23.8 g. (0.2 mole) of thionyl chloride layer and the product distilled through a helix-packed col- was added slowly while cooling with a water bath. The mixumn to yield 101.1 g. (85.5%) of l-benzyloxy-2-(N-ethyl- ture was then heated under reflux for 3 hr. The excess thionyl chloride was removed by distillation, the residue taken up carbamoxy) propane, b.p. 144-147'/0.5-0.8 mm.; n2,.' in 100 ml. of benzene and the solution washed successively 1.5020. Anal.8 Calcd. for C13H19NOa: C, 65.79; H, 8.07; N, 5.91. with water, four portions of 5% sodium bicarbonate, water, 25 ml. of 5% hydrochloric acid, and again water. After dryFound: C, 66.00; H, 8.30; N, 5.96. &( N-Ethy1carbamoxy)-i-propanol(11). 1-Benzyloxy-2-( N- ing the solution over sodium sulfate, the benzene was stripped ethy1carbamoxy)propane (23.7 g., 0.1 mole) in 200 ml. of and the residue vacuum-fractionated: b.p. 68-69'/0.5 mm.11; 99% isopropyl alcohol was reduced with hydrogen a t a b n: 1.4530; yield, 13.37 g. (80.5%). Anal. Calcd. for C6HIzNO2C1: C, 43.50; H, 7.24; N, 8.46. mospheric pressure using 12 g. of 15% palladium-on-carbon previously saturated with hydrogen. The theoretical quan- Found: C, 43.88; H, 7.20; N, 8.18. The product from the reaction of I1 and thionyl chloride tity of hydrogen was absorbed in 173 min. After filtration of the catalyst and stripping of the solvent, the product was was obtained in 60% yield, ny 1.4529;from 111, ny 1.4520. All three chloro-carbamates gave identical infrared fractionated through a short spiral-packed column, Four cub, all boiling a t 99-100'/0.5-0.6 mm. were taken: ( I ) spectra.12 Quantitative analysis of V by infrared spectrophotometry. 1.47 g., ny 1.4490, (2) 3.13 g., ny 1.4512, (3) 3.12 g. ny 1.4516, (4) 4.76 g., n? 1.4518. The total recovery was about The extinctions of 5y0 solutions in spectroscopic dichloromethane of 11, 111,and V were measured a t 9.25 p and 9.5 p 85%. Fraction 3 was analyzed. Anal. Calcd. for C6HtaNOa: C, 48.98; H, 8.83; N, 9.52. against dichloromethane in the reference beam under the following conditions: resolution, 960; response, 2:2; gain, 4. Found: C, 48.18; H, 8.64; N,9.85. The phenylurethane was prepared by mixing equimolar speed, 2. Using I and I11 as standards, calculations from amounts of the carbamate and phenyl isocyanate and allow- repeat measurements of V gave the following values for the ing the mixture to stand for several days a t room temper- composition of V: 11, 36.4%, 34.3%; 111, 63.6%, 65.77, ature. Trituration with cyclohexane caused crystallization. respectively. Recrystallization from diisopropyl ether yielded a product THENEW YORKQUININEAND CHEMICAL WORKS,INC. melting a t 83.8-85'. NEWARK, N. J. Anal. Calcd. for C13HlsN201:C, 58.63; H, 6.81; N, 10.52. S. B. PENICK A N D Co. Found: C, 59.20; H, 6.94; N, 9.97. JERSEY CITY,N. J. I-(N-Eth ylcarbamoxy)-%propanol (111). To a solution of 76 g. (1.0 mole) of propylene glycol in 250 ml. of dry benzene (9) The low yield is due to the high solubility of the interwas added dropwise below 30' in the course of 30 min. a mediate chloroformate in water. (7) Melting points are corrected, boiling points are not. (10) Reported' b.p. 99-100"/0.06 mm. (8) All analyses by Sehwarzkopf Microanalytical Eabo( 1 1) Reported' b.p. 80-81°/0.08 mm. ratory, Woodside, L. I., N. Y. (12) The instrument used was a Perkin-Elmer Model 21.
Chlorination of either I1 or I11 or V yielded the identical chlorocarbamate, b.p. 69"/0.5 rnm. ; ng 1.4530,for which we propose the structure VI on
