A Chemical Investigation of Some Florida Volatile Oils

A CHEMICAL INVESTIGATION OF SOME FLORIDA VOLATILE OILS By ARNOLD WHITNEY MATTHEWS A DISSERTATION PRESENTED TO THE GRADUATE COUNCIL OF THE UNIVERSITY OF FLORIDA IN PARTIAL FULFILMENT OF THE REQUIREMENTS FOR THE DEGREE OF DOCTOR OF PHILOSOPHY UNIVERSITY OF FLORIDA July, 1941 AGKHOWLSDGMSBT The author wishes to express his sincere appreciation to Dr. P. A, Foote under whose supervision this investigation was carried out. Dr. Foote’s suggestions and advice have always proved most helpful. The cooperation which made it possible to continue with the problem during 1939 - 194C is also gratefully acknowledged. TABLE OF CGBTSHTS Page Intro duetion 1 Sources of Material 5 Discussion of Methods of Examination and Procedures Used 8 1. Determination of Physical Constants 8 2* Determination of Free and Combined Alcohol 9 3. Detection and Separation of Phenols, Aldehydes and ketones 14 4* Identification of Volatile Aoids 20 Part I (Miscellaneous Oils) Chapter 1 23 Oil of Pyonothymus rigldas 23 Experimental 23 Discussion of Results 28 Chapter 2 30 Oil of Solldaso riglda 30 Review of Literature 30 Experimental 33 Discussion of Results 34 Chapter 3 36 Oil of Erlgeron canadensis 36 Review of Literature 36 Experimental 39 Discussion of Results 41 Chapter 4 44 Oil of He tero theca subaxillarls 44 Experimental 44 Discussion of Results 44 Chapter 5 46 Oil of Illicium floridanum 46 Review of literature 46 Experimental 49 Discussion of Results 53 Part II (Peppermint Oils 1929 - 1932) Chapter 1 57 1* Review of the Literature 57 2. The peppermint Industry in the United States 58 3. Cultivation and Volatile Oil Content 60 4. The Constituents of Oil of Peppermint 63 5. The Occurrence of Pulegone in Oil of Peppermint 65 6. The Biogenesis of Oil of Peppermint 67 Chapter 2 78 The Determination of Physical and Chemical Constants 78 Experimental 78 Apparent eater and free alcohol values of pulegone 79 Production of enol acetates 80 Brignall* s Method of Assay 81 Chapter 3 86 Fractional Distillation 86 General Procedures 86 Fractionating Columns 87 The Removal of i.etone Through the Bisulfite- Addition Reaction 92 Experimental 92 Discussion of Results 104 Chapter 4 109 Identification of Constituents 109 Low-boiling Constituents 109 Identification of Terpenes 110 Identification of Cineol 111 Identification of 1 ,3- methyl cyclohexanone 113 Menthone and Free Menthol (Washington Oils) 113 Identification of Menthone 114 Identification of Menthol 114 I enthone and Free menthol (Oil f 6, Oregon) 116 Identification of Menthone 116 Identification of Menthol 117 Identification of 3,6-Dimethylooumarone fetrahydride (ilenthofurane ) 118 Proof of Pulegone 120 In Washington Oils 120 In Oil # 6 (Oregon) 122 Identification of d-Isomenthone 122 Examination of Iiigh-hoi ling residues 125 Saponification and Fractionation 126 Identification of ienthol 128 Volatile Acids 129 Discussion of Results 130 Summary 133 Bibliography 137 Biographical Bote 143 Approval 144 INDEX TO TABLES Table 1 Page Data concerning origin of peppermint oils (1929 - 1932) 6 Table 2 Constants recorded in the literature for Soli dago oils 32 Table 3 Constants recorded in the literature for Oil of Erigeron canadensis 39 Table 4 Constants recorded in the literature for Oil of Illioium religiosum 49 Table 5 Source of Leaf 50 Table 6 Fractionation of Oil of I Hi cium floridanum 52 Table 7 Amerioan Peppermint oil output (1937 - 1939} 60 Table 8 Menthol-Menthone Relationship at Different Vegetative Stages 74 Table 9 Physical and Chemioal Constants Peppermint Oils (1929 - 1932) 78 Table 10 Comparison of Bri snail Method with U. s. P.XI Method 84 Table 11 BrignaU 1 a Assay Applied to Known Menthol Mixtures 85 Table 12 Determination of Ketone Content 86 Table 13 Fractionation of Sample # 2 (at 20 ram. } 93 Table 14 Refraotionation of Fraotiona in Table 13 94 Table 15 Fractionation of Sample ^3 96 Table 16 Refractionation of Fraction in Table 15 97 Table 17 Physical and Chemical Constants of Unabsorbed Oils (# 3» 4* and 7) 98 Table 18 Fractionation of Mixture Unabsorbed Oils 98 Table 19 Fractionation of Sample #6 99 Table 20 Physical Constants of Regenerated Pulegone 100 Sable £L Recorded Physical Constants for iulegone 101 Table 22 Refraotionation of iulegone Prom Oil # 3 (250 004) 102 Table 23 Refractionation of Iulegone from Oil 4 102 Table 24 Refraotionation of Iulegone from Oil # 7 103 Table 25 Comparison of Pulegone Fraction ( 59.64 ) with Fraotion 4 (Oil # 6) 108 Table 26 Data on Terpene Fractions (after refractionation) 109 Table 27 Cineol Determination for Low- boiling Fractions 112 Table 28 Fractionation of Saponification Residues (ISUshington Oils) 127 Table 29 Fractionation of Saponification Residue (Oil # 6) 128 1 INTRODUCTION Florida with its varied and abundant vegetation offers many possibilities for study in the field of essential oils* In 1929 vVerner (1) undertook a brief survey of some of the more readily available material. He pointed out at that time that, in addition to a large number of plants native to the State which had not been examined, there were also many others the constituents of which had been determined in other localities but which had not been studied from the standpoint of develop- ment under Florida conditions. That farmers and other citizens of the state are interest- ed in the commercial possibilities of volatile oil production is evidenced by the many inquir es received at the School of Pharmacy in Gainesville, Indeed four of the samples of oils examined in this study were sent in by B, W. Calvert, having been distilled by him from plants collected in the vicinity of Orlando, Florida# Another, oil of Illiclum florldanum , became the object of interest through an observation by Dean H. H. Hume of the College of Agriculture that the leaves of this shrub were possessed of a rather attractive odor# It has been well established that conditions of soil and climate exert an important Influence on the yield and quality of volatile oils. That Florida possesses certain advantages in this connection is Indicated from the demand in northern markets for Florida citrus fruits, garden truck, ferns, etc. It is also significant that in the case of Koellla mutlca (Michx.) Britton, 2 one of the first of the native plants to be studied at the University of Florida, it was found (2) that the essential oil contained an exceptionally high percentage of pulegone, its chief constituent. Similarly with Mentha spicata Linne' experimental culture resulted in the production of an oil with a recorded carvone content (3) far in excess of that usually found in spearmint oils. Another important advantage which Florida appears to offer to the commercial volatile oil producer is the possi- bility of two cuttings a year. For example where the Michigan and Indiana growers of spearmint harvest one crop annually, averaging 2 to 3 tons per acre, it has been found that two cuttings a year, totaling 6 to 7 tons per acre can be obtained in the University of Florida’s Medicinal Plant Garden. However in spite of the fact that it possesses an ap- parently favorable climate, some doubt was cast several years ago on the practicability of commercial production of mints, especially peppermint, in Florida. In 1927 A. F. Sievers, of the Bureau of Plant Industry, Washington, D. C., suggested that the School of Pharmacy, University of Florida, cooperate with the federal government in carrying out experimental tests with Mentha arvensls var. piperascens (Japanese peppermint). At about this time also root stocks of Mentha spicata L. and Mentha piperita L. were obtained and set out. The results of early spearmint cultivation were considered to be most promising and moderate success was achieved with Japanese peppermint but . - 3 with Mentha piperita L. the results were disappointing. In 1930 Dr. B. V. Christensen, Director of the School of Pharmacy, University of Florida, reported to the 4th Annual Symposium of the Genus Mentha (4) that a supposedly true type of Mentha piperita L. grown in the University’s Medicinal Plant Garden the previous season had yielded nn oil which assayed only 7.23# menthol and contained about 80# pulegone. He pointed out that the plant may have undergone dehybridization or a delayed re- duction in the process of metabolism and expressed the hope that further study might explain the low menthol content of peppermints grown In the South, Since several of the peppermint oils of the years 1929, 1930, 1931, and 1932 were still available, it was felt that a more detailed study of their composition and especially of the non-pulegone constituents should be undertaken. It is not im- probable that these oils, by virtue of their abnormality, may disclose data which will later prove of value to others In their studies of the biogenesis of peppermint oil and the genetics of the genus Mentha This present investigation has therefore been undertaken with a double objective in view: 1. To determine the physical and chemical constants of several native oils and to Identify such of their constituents as the circumstance of limited supply might permit. 2, To examine several oils distilled from Florida-; r own Mentha piperita L. during the period 1929-32 and known to be low in menthol content and in particular to seek to determine what other changes in composition may accompany failure to develop menthol and to record all other evidence of abnormality. - 5 - SOURCES OF MATERIAL 1* The following oils, included herein in Part I, were sent in for examination by B. W, Calvert of Orlando, Florida, having been distilled by him from plants collected in that region. The oils were received in the fall of 1936 and the quantities available for this investigation are indicated? Oil of Pycnothymus rlgldus .

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