THE SYNTHESIS OP SOIÆE MONO-ALKYXCYCLO- PROPANES AND METHYXENECYCLOPROPANE DISSERTATION Presented in Partial Fulfillment of the Requirements for the Degree Doctor of Philosophy in the Graduate School of the Ohio State University By JAlffiS THURMOND GRAGSOK, M.Sc. The Ohio State University • Tf* • ••• • * 1951 Approved by: Advisor ACKl'IOWLEDGMENT Sincere appreciation is expressed to Dr. C. E. Boord for his constant interest and guidance during the course of this work. Acknowledgment is also made to Dr. K. W. Greenlee for his continual interest and many helpful suggestions. Thanks are expressed to the American Petroleum Insti­ tute Research Project 45. Without its aid this work could nôt have been completed. 892489 i--ÎL TABLE OP CONTENTS PAGE I. Introduction................................... 1 II. General Discussion A. Historical ............................... 5 B. Present Research .......... 8 III. Experimental A. Special Apparatus ................. 20 B. Methylcyclopropane 1. l-Chloro-3-bromo-8-methylpropane .... 22 2. Ring Closure ........................ 22 3. A second synthesis ............. 23 C . EthylcycTopropane 1. Reaction scheme (1) a. l-Ethoxy-3-hydroxypentane ..... 26 b. l-Ethoxy-3-bromopentane ...... 27 c. Dealkoxydebromination......... 28 2. Reaction scheme (2) a. 3 -Hydr oxypent en e -1 ............ 29 b. 3-Bromopentene-l .......... 31 0 . 1,3-Dibromopentane ............ 32 d. Ring closure .................. 32 3. Reaction scheme (3) 33 D. n-Propylcyclopropane 1. Reaction scheme (1) ii PAGE a. l-Ethoxy-3 -liydPoxyiiexan0 ..... 35 b. l-Ethoxy-3-bromohexane ....... 35 c. Ring closure ........ 36 2. Reaction scheme (2) a. 3 -Hydr oxyhexene -1 ............. 38 b. 3-Bromohexene-l ........... 38 c. 1,3-Dlbromohexane ............. 38 d. Ring closure .................. 39 E. n-Butylcyclopropane 1. Reaction scheme (1) a. l-Ethoxy-3-hydroxyheptane ..... 40 b. l-Ethoxy-3-broraoheptane ....... 40 c. Dealkoxydebromination ......... 41 2. Reaction scheme (2) a. 5-Hydroxyheptene-l ............ 43 b. 3-Bromoheptene-l .............. 43 c. 1,3-Dibromoheptane ............ 44 d. Ring closure ...... 44 3. Reaction scheme (.3) ................ 45 P. Attempted synthesis of phenylcyclopropane 1. 1-Ethoxy-3-hydroxy-3- phe nylprop a ne .. 50 2. l-Ethoxy-3-bromo-3-phenylpropane .... 57 3. Attempted ring closure a. Zinc and alcohol ........ 57 b. Magnesium and ether ...... 58 Ill PAGE G. An attempt to prepare methyl cyclobutyl ketone 1* 6-Bromo-hexanone-2 ........... 59 2. Attempted ring closure ............ 60 H. Synthesis of methyleneoyclopropane 1. Chlorination of methallylchloride .. 61 2. Attempted ring closure a. With zinc and acetamide ...... 63 b. With Magnesium ................ 64 3. Proof of structure a. Physical constants ............ 67 b. Ozonolysis ................. 77 c. Hydrogenation ............ 79 d. Infrared spectral analysis .... 84 e. Conclusions ................. 8 6 IV. Summary ... ......... 96 V. Bibliography ................................. 98 Autobiography Iv INDEX TO TABLES TABLE NO. PAGE I Physical Properties of n-Butylcyclopropane and Related Hydrocarbons ............... «. 46 II Summary of Hydroxylic Compounds Prepared in This Work ....................... 93 III Summary of Halides Prepared in This Work .. 94 IV Summary of the Physical Properties of Cyclopropane Hydi'Ocarbons Prepared in This Work ..................................... 95 V INDEX TO PLATES PLATE NO. PAGE I Infrared Spectrogram of Methylcyclopropane Prepared from l-0hloro-3-bromo-2-methyl- propane ................................ 51 II Infrared Spectrogram of Methylcyclopropane Prepared from l,3-Dibromohutane ..... 52 III Infrared Spectrogram of n-Propylcyclopropane Prepared from l-Ethoxy-3-bromohexane ..... 53 IV Infrared Spectrogram of n-Propylcyclopropane Prepared from 1,3-Dibromohexane ..... 54 V Infrared Spectrogram of n-Butylcyclopropane Prepared from l-Ethoxy-3-bromoheptane .... 55 VI Infrared Spectrogram of n-ButylCyclopropane Prepared from 1,5-Dibromoheptane ...... 56 VII Infrared" Spectrogram of Methylenecyclopro­ pane , 8 8 VIII Infrared Spectrogram of 1,2-Butadiene .... 89 IX Infrared Spectrogram of Headings from Dis­ tillation of Methyleneoyclopropane 90 X Infrared Spectrogram of Residue from Dis­ tillation of Methyleneoyclopropane 91 XI Infrared Spectrogram n-Butane ............. 92 THE SYNTHESIS OP SOME MONO-ALKÏLCYOLOPROPANES AND METHYLENEOYCLOPROPANE Introduction Cyclopropane was first prepared by Freund (1,2), who treated trimethylene dibromide, at the boiling point, with sodium. Gustavson (3) improved the yield and quality of cyclopropane by substituting zinc for sodium, using alco­ hol as a solvent. This synthesis of cyclopropane and its homologues from the corresponding dibromide and zinc is now Imown as the Gustav son reaction. Although there are many other procedures for making cyclopropane homologues, chief among which are the decomposition of pyrazolines and dehy- drohalogenation reactions, the Gustavson method, with modi­ fications, is usually the preferred one. The synthesis, of mono-alkylcyclopropanes has fallen far behind that of the polyallcyl derivatives, because of the lack of a suitable method of preparing the 1,3-dibro- mides. The dibromides are most conveniently prepared by treating the corresponding glycols with phosphorus tribro­ mide, but the availability of 1,3-glycols limits this method. It was for this reason that some other possibili­ ties for preparing mono-alkylcyclopropanes were investi­ gated. In the laboratory of the American Petroleiom Institute Research Project 45, it was especially desired to find a suitable method of preparing mono-alkylcyclopropanes which could be utilized in producing reasonably large quantities of the pure hydrocarbons for engine testing. The second aim of this work was to investigate some reactions which might lead to the synthesis of cyclobutane and its. homologues. General Discussion Historical Methylcyclopropane was first prepared by Démjanoff (4), who treated 1,3-dibromobutane with zinc in alcohol, in a procedure analogous to that of Gustavson. He reported the product as boiling at 4-5°C. Ho mention was made of the formation of olefins or their removal from the product. Lott and Christiansen (5) reported, much later, of preparing methylcyclopropane by the same procedure. They claimed that the product was 99.3% cyclic and 0.7% olefin (as determined by a bromine titration) and that it boiled at 2-5°C., mostly at 4-5°G. 1,3-Dichloroisobutane was said to give largely isobutylene. Recently, Roberts and Mazur (6 ) reported the prepara­ tion of methylcyclopropane from 1,3-butylene glycol in an overall yield of 62^. The boiling point of their product was 2 °C. Smith and Condon (7) have prepared methylcyclopropane in such a manner as to give a product which could be re­ moved from its impurities by distillation. Prom 117.5 grams of iso butyl chloride and 1 0 grams of sodium, they ob­ tained 3.1 grams of methylcyclopropane, 8 . 8 grams of iso­ butane (b.p. -11.7°), 4.7 grams of isobutylene (b.p. -6.9°), and 78 grams of recovered isobutyl chloride. They reported the boiling point of methylcyclopropane as 0°C. at 750 mm. An infrared spe-ctrogram of the sample showed a strong, band in the 9.9 micron region which is characteristic of the cyclopropane ring. The preparation of ethylcyclopropane by the early workers (8,9) consisted of the hydrogenation, of question­ able samples of vinylcyclopropane. Philipow (10) prepared ethylcyclopropane by hydrogenating the hydrazone of methyl- cyclopropyl ketone. Lespieau (11) reported the synthesis of ethylcyclopropane by the Gustavson procedure. The pro­ duct had physical properties which were in fair agreement with the accepted ones, but was admittedly impure and very difficult to purify. Herr, Vvhitmore, and Schiessler (12) prepared ethylcy­ clopropane in high purity by a Wolff-Kishner reduction of methyl.cyclopropyl ketone, They decomposed the hydrazone of methyl cyclopropyl ketone with sodium me thy late in tri­ ethylene glycol at a temperature of 200°G. Van Volkenburgh ( 13 ) . improved the method somewhat by using dlethylene glycol and sodium hydroxide in place of the sodium methylate. The yield of purified ethylcyclopropane was 12%, Apparently, Boeseken and Takes (14) are the only work­ ers who have reported synthesizing n-propylcyclopropane. Their procedure is best described by the following equa­ tions : EtOOCGHgCOOEt + CHgOHgCHgBr -- > EtOOOCH(COOEt ) OHgOHgÇHg EtOOCGH(OOOEt )OHgOHgCH^ + Na(Hg)/EtOH ^ OHgOHOH(CHgOH)CgB^ CHgORCH( OHgOH) OHgOHgOHg -f-PBr^ ^ CHgBrGK(GHgBr )OHgGHgGEg GHgBrGH ( OHgBr ) GEgGHgGHg 4- Zn -- ^ GHg— CHGHgGHgG% \ / OHg The yields were not given, but they were admittedly low, and only a few grams of the hydrocarbon were obtained. Shortridge (15) attempted to prepare 2-alkyl-1 ,3-pro- panediols, which then would be converted to the correspond­ ing dibromides and alkylcyclopropanes. The scheme was as follows ; CH5 GH2 GH2 GHO -f- HGHO --- 9 ^ CHgGHgOH( OHgOE)OHO OHgOHgGH ( OHgOH ) GHO + H g > GHgOHgGH(CHgOH)g Several runs were made with formaldehyde and butyraldéhyde, with varying conditions, in an effort to obtain a signifi­ cant yield of the aldol. The highest yield obtained was All attempts to hydrogenate the aldol to the diol were unsuccessful because of dealdolization during the heat­ ing required for the hydrogenation. Van Volkenburgh (13) reported the preparation of iso- propylcyclopropane by the hydrogenation of isopropenyl- cyclopropane, which was obtained by sulfuric acid catalyzed dehydration of