Communications to the EditorVol. 69 methoxyl contents of the dark brown amorphous products were only a fraction of those of the original acids. That from ferulic acid contained 9.8% methoxyl after five minutes of oxidation, and after five hours of reaction the product from vanillic acid contained 6.5% methoxyl.Methoxyl groups previously reported lost during the periodate oxidation of purified ammonium lignin sulfonate1 have been identified as methanol in the volatile products of the oxidation, as measured by the colorimetric method described by Simmons.6 The evidence cited here indicates an attack upon the aromatic nucleus in the lignin sulfonic acids. The absence of any easily discernible stoichiometry and failure to isolate definite products precludes any ready interpretation for the course of the reaction, without further investigation. Such a study is being undertaken in this Laboratory.
The failure of organic reactions to give yields approaching the theoretical is well known. Processes which deviate most from the theoretical involve either an apparent metathesis or the elimination of an inorganic molecule such as water, halide acid or nitrogen. These reactions are also the chief source of the rearrangements which have become so common in organic chemistry. In the years since Fittig discovered the pinacolone rearrangement,2 countless other rearrangements have been found and many explanations have been evolved.3 These explanations have assumed intermediates including cyclopropane rings, ethylene oxide rings, olefins, univalent nitrogen, bivalent carbon, ordinary ions, bipolar ions and chelate compounds.The purpose of this paper is to show that rearrangements and the peculiarities of organic "metathetical" reactions have a common mechanism based on the very nature of the "bonds" in organic compounds as contrasted to the ionic attachments in inorganic molecules. All the essentials of the mechanism proposed in this paper are old and are implicit in conceptions of atoms and molecules introduced during the last twenty years by G.
__________________ 117 Introduction _______________________________________ 117 Acknowledgments_ ____________________________ 117 Cranial morphology of some Oligocene Artiodactyla____-118 Cranial morphology of Merycoidodon ______________ 118 Bones of the skull___.__________________ 118 Occipital.__________________________ 118 Basisphenoid_ ________________________ 120 Alisphenoid_ __________________________ 123 Presphenoid_ _________________________ 123 Orbitosphenoid-_ ______________________ 124 Ethmoid and turbinals________________ 124 Vomer__________________________ 126 Preinterparietal and interparietal-_______ 126 Parietal.. ______________________ 126 Frontal-_____________________ 126 SquamosaL ____________________________ 127 Tympanic region. __________________________ 131 Pars petrosa of the periotic bone________ 131 Middle ear and surrounding structures--_ _ 132 External auditory meatus______________ 135 Pars mastoidea of the periotic bone _______ 135 Pneumatic sinuses__________________________ 136 Circulatory system of the skull-______________ 137 Arteries _______________________________ 137 Veins and venous sinuses._______________ 138 Dorsal sinus system_________________ 138 Basilar sinus system_______________ 139 Subsphenoid veins and sinus venosus ossis sphenoidalis_________________ 140 Nerves of the skull region__________________ 141 Cranial morphology of Poebrotherium______________ 141 Bones of the skull_________________________ 141 Tympanic region.__________________________ 144 Pars petrosa of the periotic bone________ 144 Middle ear and surrounding structures. _ _ _ 145 External auditory meatus______________ 146 Pars mastoidea of the periotic bone _______ 146 Pneumatic sinuses__________________________ 146 Circulatory system of the skull-_____________ 147 Arteries.,_____________________________ 147 Cranial morphology of some Oligocene Artiodactyla-Con. Cranial morphology of Poebrotherium-Continued Circulatory system of the skull-Continued ILLUSTRATIONS FIGURE 14.
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