1. The Problem of Tautomerism.- 1. Tautomerism as Dynamic Isomerism.- 1.1. Molecular Structure and Isomerism.- 1.2. Bond Rupture Formation Criterion.- 1.3. Tautomerism and Rearrangements.- 1.4. Thermodynamic and Activational Scale of Tautomeric Processes.- 2. Degenerate Tautomerism.- 3. Methods for Investigating Tautomeric Systems.- 4. Butlerovs and Laars Tautomeric Systems.- 5. Tautomerism and the Mechanisms of Organic Reactions.- 6. Classification of Tautomeric Reactions.- 6.1. Prototropy.- 6.2. Metallotropy.- 6.2.1. ?, ?-Transfers.- 6.2.2. ?, ?-Transfers.- 6.2.3. ?, ?-Transfers.- 6.3. Anionotropy.- 6.4. Valence Tautomerism.- 6.4.1. ?-Valence Tautomerism.- 6.4.2. ?, ?-Valence Tautomerism.- 6.4.3. ?-Valence Tautomerism.- 7. Conclusion.- References.- 2. Carbonotropy.- 1. The Problem of Carbonotropy.- 1.1. General Principles.- 1.2. Choice of a Migrant.- 2. Sigmatropic Acyl and Aryl Rearrangements.- 2.1. Acyl 1,3-Rearrangements.- 2.2. Aryl 1,3-Rearrangements.- 2.3. 1,5-and 1,7-Acyl Rearrangements.- 3. Acylotropic Tautomerism.- 3.1. Tautomeric 1,3-Acyl Rearrangements of the N,N?-diarylamidine Derivatives.- 3.2. Stereochemistry of Acyl Migration.- 3.3. Tautomeric 1,5-Acyl Rearrangements of O-Acylenols of 1,3-Diketone.- 3.4. Acylotropy of 9-Acyloxyphenalen-l-ones.- 3.5. Tautomerism of 2-Acyloxytropones.- 4. Tautomeric Rearrangements of Aryl Groups.- 4.1. 1,3-Rearrangements of Aryl Groups.- 4.2. O,O?-Migrations of the Aryl Groups in O-Aryl Derivatives of Tropolone and the Synthesis of Bipolar Spiro- ?-Complexes.- 4.3. Valence Tautomerism of O-Aryl Ethers of o-Hydroxybenzaldehydes and their Imines.- 5. Carbonotropic Tautomerism in Ions, Radicals and Cyclopolyenes.- 5.1. Acylotropic and Arylotropic Rearrangements in Anions.- 5.2. Acylotropy in Phenoxyl Radicals.- 5.3. Tautomeric Rearrangements of Carbocations.- 5.4. Acyl and Aryl Migrations in Cyclopolyenes.- References.- 3. General Principles of the Design of Tautomeric Systems.- 1. Possibilities of Quantum Mechanical PrlĂ7