I AN INTRODUCTION TO THE CHEMISTRY OF PLANT PRODUCTS LONGMANS, GREEN AND CO. Ltd. 39 PATERNOSTER ROW, LONDON, E.C. 4 6 OLD COURT HOUSE STREET, CALCUTTA 53 NICOL.ROAD, BOMBAY 167 MOUNT ROAD, MADRAS LONGMANS, GREEN AND CO. 55 FIFTH AVENUE, NEW YORK 221 EAST 20TH STREET, CHICAGO TREMONT TEMPLE, BOSTON 210 VICTORIA STREET, TORONTO H // ^/ AN INTRODUCTION TO THE CHEMISTRY OF PLANT PRODUCTS Vol. I. ON THE NATURE AND SIGNIFICANCE OF THE COMMONER ORGANIC COMPOUNDS OF PLANTS BY PAUL HAAS, D.Sc, Ph.D. READER IN PLANT CHEMISTRY IN THE UNIVERSITYrOF LONDON, UNIVERSITY COLLEGE AND T. G. HILL, D.Sc, A.R.C.S. READER IN VEGETABLE PHYSIOLOGY IN THE UNIVERSITY OF LONDON, UNIVERSITY COLLEGE FOURTH EDITION WITH DIAGRAMS LONGMANS, GREEN AND CO. LONDON ??? NEW YORK ??? TORONTO 1928 Made in Great Britain PREFACE TO THE FOURTH EDITION. The original intention of this work was to provide students with an account of the chemistry and physio- logical significance of some of the more important substances occurring in the plant. The founding of Chairs of Biochemistry during recent years, with the consequent dissemination of biochemical knowledge, would appear to give just cause for the discontinuance of the present work, but it is not possible for all students to avail themselves of the facilities offered, and it is primarily for such students that the work is intended. The enormous output of papers and the recent advances in knowledge have necessitated much revision, and, in the main, the present edition has been rewritten. In so doing we have borne in mind the requirements of those approaching the subject from different angles and have included a certain amount of somewhat elementary information, both botanical and chemical, and also have admitted certain rather more advanced aspects of the subject even though they be matters of controversy. We fully recognize that this involves some dispro- portion, some lack of balance, but this is inevitable. R H. T. G. H. June, ig28. PREFACE TO THE FIRST EDITION. The importance to the botanist of a working knowledge of chemistry can hardly be overestimated, since vege- table physiology is replete with problems awaiting solution by the combined application of botanical and chemical methods. Teachers of vegetable physiology, however, not in- frequently find that their students' knowledge is deficient in just those branches of chemistry which are of parti- cular importance to the botanist, which is, no doubt, largely due to the fact that those compounds which are of interest to the botanist do not necessarily fit into the scheme of instruction of the chemist. The present work is an attempt to provide such students, who are assumed to have some acquaintance with chemistry, with an introductory account of the chemistry and biological significance of some of the more important substances occurring in plants. In compiling this book various sources of informa- tion have been laid under contribution, and although the point of view is, in the main, purely chemical and botanical, the economic aspect has not been lost sight of, and, where possible, mention has been made of the uses of plant products and of the manufacturing processes employed in their preparation. P. H. T. G. H. December^ igi2. VI PREFACE TO THE THIRD EDITION. The necessity for a third edition has afforded an oppor- tunity for making certain changes in the arrangement of the subject-matter. In order to give the more purely physiological aspect of the subject fuller treatment, with- out at the same time unduly increasing the size of the volume, the work now appears in two parts. Volume I. is essentially the same in scope as the earlier editions and deals primarily with the more chemical side of the subject : a sufficiency of plant physiology has, however, been retained to make the account reasonably complete and to preserve the character of the work. Volume II., which is in preparation, will be devoted to more purely physiological problems, and will contain some of the matter previously found in the original volume. The present volume has been brought up to date as far as is possible ; some portions have been rewritten. Section VIII. for example, and in other sections a certain amount of rearrangement has been deemed advisable. P. H. T. G. H. October, ig20. vn CONTENTS. PREFACE SECTION I.??? FATS, OILS, AND WAXES Fats .... Occurrence Constitution Chemical properties Saponification Extraction Characterization Quantitative estimation Quantitative methods for characterization Acid number . Saponification value. Unsaponifiable residue Iodine value . Reichert Meissl value Acetyl value . Spontaneous changes Rancidity Drying and resinification Industrial uses Hardening of oils Physiological significance Microchemical reactions Waxes Properties Sterols Cholesterol Reactions Phytosterols Distinction between cholesterol and phytosterol Estimation of sterol content of an unsaponifiable residue Lipins .... Phospholipins Lecithin . Kephalin Cerebrosides or galactolipins Occurrence Physiological significance PAGE V I I 4 9 lo 12 14 i6 20 21 21 22 23 26 27 28 28 29 31 34 34 44 44 45 46 46 47 48 49 50 51 53 53 55 56 56 57 SECTION II.??? ALDEHYDES AND ALCOHOLS Formaldehyde Alcohols Occurrence 60 65 69 69 IX 37638 CONTENTS Inositol Preparation Identification . Manufacture of ethyl alcohol PAGE 71 72 72 73 SECTION III.??? THE CARBOHYDRATES Classification .... Solubilities ..... General tests .... Constitution and isomerism of sugars Oxidation products of sugars Characterization of sugars Monosaccharides .... Pentoses .... General properties . Properties of individual pentoses Arabinose Xylose Ribose Apiose Methyl pentoses Hexoses .... Distinction between aldoses and ketoses Glucose or dextrose . Occurrence Preparation Properties Reactions Microchemical tests Fructose or levulose Occurrence Preparation Properties Reactions Constitution Sorbose Galactose Occurrence Preparation Properties Detection Mannose Occurrence Preparation Properties Detection Heptoses Disaccharides Action of enzymes on disaccharides Cane sugar, sucrose or saccharose Occurrence Preparation Constitution Properties Reactions Turanose Maltose Properties and reactions Isomaltose Cellobiose Iso-cellobiose 76 77 78 79 80 84 86 88 88 90 92 92 92 93 93 93 94 96 96 96 97 98 98 99 lOI loi lOI 102 102 102 103 104 104 104 105 105 106 106 106 106 107 107 107 108 109 109 III "3 "3 114 "5 "5 116 117 119 119 CONTENTS XI Gentiobiose . Trehalose . . - Lactose or milk sugar Melibiose ... Disaccharides produced by the union of a hexose with Primeverose . Vicianose Strophanthobiose Trisaccharides Raffinose Detection Melecitose Stachyose Gentianose . . Sugars of unknown molecular weights or sugar saccharides . . . . ??? Abnormal or ill-delined sugars Estimation of sugars . . . . ??? Volumetric methods .... Estimation by means of Fehling's solution Estimation of pentoses Estimation of reducing sugars Estimation of galactose and mannose Estimation of cane sugar . Estimation of maltose Estimation of mixtures of sugars Estimation by means of Pavy's solution Estimation by means of Benedict's solution Estimation by Bertrand's method Gravimetric methods Estimation of pentoses Reducing sugars other than pentose Estimation of glucose as osazone Estimation of natural mixtures of sugars Polarimetric methods Polysaccharides Hexosans Glucosans Starch or amylum Preparation Purification Properties Composition of the starch grain Action of acids on starch . Action of malt diastase on starch Action of bacteria on starch Reactions Estimation of starch Dextrins Occurrence Formation from starch General properties . Commercial dextrin Glycogen Preparation Properties Identification Estimation Lichenin and isolichenin Paradextrane and paraisodextrane Fructosans . Inulin . a pentose like poly- PAGB 119 120 120 120 121 121 121 122 122 122 124 124 125 126 126 126 126 126 128 128 130 130 132 134 135 137 137 139 140 140 141 146 146 146 149 149 154 161 163 163 164 165 167 167 169 170 170 171 171 173 173 173 xn CONTENTS Preparation Characters Identification . Physiological significance . Inulin-like substances Hemicelluloses .... Properties .... Constitution .... Mannan .... Paramannan . Carubin or secalane . Xylan .... Araban .... Wood gum Galactan Mixed galactans Amyloid Gums ...... Microchemical reactions . Gum-arabic .... Reactions Gum-tragacanth Wound gum .... Mucilage .... Function Pectic bodies Isolation of pectins from the tissues Properties Microchemical reactions . Estimation Action of enzymes on pectins Origin and constitutional relationship Changes taking place on ripening Cellulose ...... Classification .... Properties ..... Solubility .... Action of various chemicals on cellulose Oxycellulose .... Properties Constitution ..... Microchemical reactions Lignified membranes .... Chemistry of lignin Isolation and constitution of lignin . Estimation ..... Estimation of cellulose in lignified tissues Nature of the union between lignin and cellulose Microchemical reactions . Cutinized membranes Suberized membranes Microchemical reactions of sub...
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