Eastern Illinois University The Keep Masters Theses Student Theses & Publications 1982 Cleavage and Deoxygenation of Phenolic Ethers Derhsing Luu Eastern Illinois University This research is a product of the graduate program in Chemistry at Eastern Illinois University. Find out more about the program. Recommended Citation Luu, Derhsing, "Cleavage and Deoxygenation of Phenolic Ethers" (1982). Masters Theses. 2918. https://thekeep.eiu.edu/theses/2918 This is brought to you for free and open access by the Student Theses & Publications at The Keep. It has been accepted for inclusion in Masters Theses by an authorized administrator of The Keep. For more information, please contact [email protected]. THESIS REPRODUCTION CERTIFICATE TO: Graduate Degree Candidates who have written formal theses. SUBJECT: Permission to reproduce theses. 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I i.II I 1· Date Author I respectfully request Booth Library of Eastern Illinois University not allow my thesis be reproduced because -�� ' \ ) Date Author m CLEAVAGE AND DEOXYGENATION OF PHENOLIC ETI-IERS !TITLE) BY DERHSING LUU THESIS SUBMITTED IN PARTIAL FULFILLMENT OF THE REQUIREMENTS FOR THE DEGREE OF MASTER OF SCIENCE IN CHEMISTRY IN THE GRADUATE SCHOOL, EASTERN ILLINOIS UNIVERSITY CHARLESTON, ILLINOIS HEREBY RECOMMEND THIS THESIS BE ACCEPTED AS FULFILLING I THIS PART OF THE GRADUATE DEGREE CITED ABOVE I ADVISER ..._}'u vt � l 1· DATE'l.1j, 1f°J. COMMir'TEE MEMBER f I It I L'1,\1�l. �DATE COMMITTEE MEMBER ! ! 'II I l, DEPARTMENT CHAIRPERSON 1. I· I t i' i ------··-· ---·--- ·--·- --- _ _, . ... · ' '?.-..... • .;-;:- . ... �,..... CLEAVAGE AND DEOXYGENATION OF PHENOLIC ETHERS By Derhsing Luu 420505 1 Title of Thesis: Cleavage and Deoxygenation of Phenolic Ethers Derhsing Luu, Master of Science, June 1982 Thesis directed by : Dr. David H. Buchanan ABSTRACT Dibromotriphenylphosphorane (DTP) in acetonitrile at 50°C was found to cleave 8-naphthylmethyl phenyl ether in preference to ·8-naphthyl benzyl ether, 62% and 30% cleavage, respectively. Reaction of 8-naphthyl benzyl ether in dichloromethane at reflux produced 67% cleavage . The quasiphosphonium complexes obtained by reaction of phen�lic com­ pounds with DTP were found to be reduced by several reducing reagents to give the corresponding aromatic hydrocarbons. Reaction of p-cresol with DTP , followed by lithium aluminum hydride reduction gave 38% toluene; sodium naphthalide reduct ion in THF gave 32% toluene; sodium in liquid ammonia reduction gave 12% toluene ; sodium naphthalide reduction in DMF gave 15% toluene. Reaction of 8-naphthol with DTP fol lowed by lithium aluminum hydride reduction in THF gave no naphthalene. ii ACKNOWLEDGEMENT I would like to thank my Research Advisor, Dr. David H. Buchanan, for his help and guidance and the Faculty and Staff of the Chemistry Department of Eastern Illinois University. I also would like to thank my fami ly, especially my mother, whose support, care and love made the wh ole project possible. iii TABLE OF CONTENTS Ab stract . i Acknowledgement ii List of Figures iv List of Tables . � v I. Introduction . 1 II. Experimental . 10 III. Results and Discussion 34 IV. References .. 78 V. Vita .... 81 iv List of Figures Figure No. 1 Graph of Wi/Ws vs. Ai/As (Rxn. VI .A) . 34 2 Graph of Wi/Ws vs. Ai/As (Rxn. IV.B) 38 3 Graph of Wi/Ws vs. Ai/As (Rxn . V) 40 4 Graph 0£ Wi/Ws vs. Ai/As (Rxn. V) 41 s IR Spectrum of Tri-n-Butyl phosphine Oxide 43 6 IR Spectrum of Triphenyl phosphine Oxide 43 7 IR Spectrum of Dibromotriphenylphosphorane (DTP) 47 8 IR Spectrum of p-Cresol . • . SS 9 IR Spectrum of Triphenylphosphonium-tolyloxy Bromide. SS 10 IR Spectrum of 8-Naphthol . • . S6 il IR Spectrum of Triphenylphosphonium-8-naphthoxy Bromide S6 12 Graph of Wi/Ws vs. Ai/As (Rxn. VI) . S9 13 Graph of Wi/Ws vs. Ai/As (Rxn . VI) . 60 14 Graph of Wi/Ws vs. Ai/As (Rxn. VII I.A) 63 lS Graph of Wi/Ws vs . Ai/As (Rxn . VIII.C) 6S 16 Cyclic Voltammegram of Acetonitrile and 0.1 M TEAP 71 17 Cyclic Voltammegram of 1 mM p-Cresol and 0.1 M TEAP . 72 in Acetonitrile 18 Cyclic Voltammegram of 1 mM DTP and 0.1 M TEAP in 73 Acetonitrile 19 & 20 Cyclic Voltammegram of 1 mM Triphenylphosphonium 74' 7S tolyl.oxy bromide and 0 .1 M TEAP in Acetonitrile v List of Tab les Tab le No. 1 GC Standardization of n-Butyl Bromide . 34 2 Quantitative Analysis of n-Butyl Bromide for Rxn. VI.A ..36 3 GC Standardization of Benzyl Phenyl Ether . • 38 · 4 Quantitative Analysis of Benzyl Phenyl Ether for . .. 38 furn. IV. B 5 GC Standardization of 1-Bromooctane . 40 6 GC Standardization of Di-n-Octyl Ether . 40 7 Quantitative Analysis of 1-Bromooctane for Rxn . V . 43 8 Quantitative Analysis of Di-n-octyl Ether for Rxn . V ...43 9 NMR Quantitative Analysis for Reactions for Rxns . II .A, 46 III.A, II.B, and III.B 10 NMR Standardizations for Rxns. II.A, III.A, II.B and III.B 47 11 NMR Quantitative Analysis for Rxns. IV.A and III.C 52 12 Experimental Results for Ether Cleavage Reactions . 53 13 GC Standardization of phenyl propionate . 58 14 GC Standardization of phenol 58 15 Quantitative Analysis of Phenol and Phenyl Propionate . 61 for Rxn VI 16 GC Standardization of Toluene . 62 17 GC Standardization of p-Cresol ..64 18 Quantitative Ana lysis of Toluene and p-Cresol 64 19 Experimental Results of the Reductio� of Phenolic . 67 Compounds INTRODUCTION Ether bridges have long been considered to be important cross- linking agents in the structure of coal 1 and many reports have shown 2 that cleaving ethers increases the solubility of coal . Ignasiak et 3-5 al . also reported that cleaving the ether linkage in coal fractions with (1) Na in liquid ammonia or (2) K/THF/naphthalene followed by alkyl- ation decreased the average molecular weight of the·soluble coal fraction. -Selective cleavage of the cross links offers the possibility of depolymerizing the coal to a mixture of the component clusters which, ' because of their lower average molecular weight , should be soluble in simple solvents . This work might give us a chance to u�derstand the structure of coal. Also, this knowledge might suggest improvements in current coal conversion technology. There are four types of ether linkages that may be present in the · coal structure, i.e. di-alkyl ether, aryl-alkyl ether, aryl -benzyl ether, 6 7 and di-aryl ether linkages which were suggested by Wiser and Chakrabatty. Ethers arc rel ati vcly inert to most reagem:s. They are stable to base, to catalytic hydrogenat ion, and most other reducing agents. Various cleaving reagents have been used to cleave ethers . The classical nethod for alkyl ethers is treatment with concentrated hydrohalic acid such as HBr and !1!8-9 at high temperature (see Equations (1)-(5)). The mechanism involves protonation of the ether oxygen then SN2 attack by halide ion to yjcl<l one mole of alcohol and one mole of alkyl halide. The alcohol produced reacts :further with the acid to produce a second nole of alkyl halide and 2 a mole of water. Ether cleavage by this method also could fol low the �1 mechanism if the leaving group could form a stable carbonium ion such as tertiary alkyl group. Aryl alkyl ethers could also be cleaved HBr (1) R-0-R R-0-R + Br Heat I H (2) ROH + RBr (3) (4) RBr Br HBr (5) R-OH by this method. The reaction wou ld also follow either an S l or S 2 N N mechan ism to produce phenol and alkyl halide. The second method of cleaving ethers which was mentioned earlier as a coal reagent is the use of Na or K in liquid anunonia solution. This method is effective for cleavage of aryl and benzyl ethers but alkyl ethers 3,8,10 are re 1 at1ve. 1 y inert.. A mechanism is shown in Equations (6)-(9). Na . + (6) ArOAr ArOAr + Na liquid NH 3 . (7) ArOAr Ar + ArO l 3 Na (8) Ar Ar + (9) Ar + ArO ArH + ArOH solvent . 11-12· A t h1r d met ho d o f c 1 eav1ng eth ers uses b oron tY1.h a 1° 1 d e to c 1 eave aliphatic, cyclic, and mixed aliphatic aromatic ethers at room temperature (see Equations (10)-(12)). (10) R'OR + BX3 R'OBX + RX 2 (I) 3 + + 3 (11) R'OBX BX3 B 03 R'X 2 2 (I) (if R' is an alkyl group) H 0 2 (12) R'OBX R'OH + 2HX + H3so3 2 (if RI is an aryl group) Reaction of one mole of an aliphatic or cyclic ether with one mole of boron trihalide produces the alkoxydihaloborane (I) and the alkyl halide. 'foe alkoxydihaloborane is unstable and decomposes to boron trihalide, boric acid, and the alkyl hal ide. Aryl-alkyl ethers react with boron tri- halide to form alkyl halides and phenoxydihaloboranes, which do not form aryl hal ides. Arter hydrolysis, phenoxydihaloborane will decompose to produce the corresponding pheno l.