Abstract: A reversible thermosensitive composition including a coloring agent and a developer and capable of assuming a colored state and a discolored state depending upon the thermal hysteresis thereof. The developer is a phenol compound represented by the formula: ##STR1## wherein n is an integer of between 1 and 3, X represents a divalent group having a nitrogen atom or an oxygen atom, R.sup.1 represents a substituted or non-substituted aliphatic hydrocarbon group having at least two carbon atoms and R.sup.2 represents a hydrocarbon group. A reversible thermosensitive recording medium has a thermosensitive recording layer containing the above composition.

Abstract: A reversible thermosensitive composition including a coloring agent and a developer and capable of assuming a colored state and a discolored state depending upon the thermal hysteresis thereof. The developer is a phenol compound represented by the formula: ##STR1## wherein R.sup.1 and R.sup.3 represent, independently from each other, a substituted or non-substituted hydrocarbon group, R.sup.2 represents a substituted or non-substituted aliphatic hydrocarbon group having at least two carbon atoms, with the proviso that the total number of carbon atoms of R.sup.1, R.sup.2 and R.sup.3 is at least 8, X and Y represent, independently from each other, a divalent group having a nitrogen atom or an oxygen atom and r is an integer of between 1 and 3.

Abstract: A reversible thermosensitive composition including a coloring agent and a developer and capable of assuming a colored state and a discolored state depending upon the thermal hysteresis thereof. The developer is a phenol compound represented by the formula: ##STR1## wherein R.sup.1 represents a substituted or non-substituted divalent hydrocarbon group having at least two carbon atoms, R.sup.2 represents a substituted or non-substituted hydrocarbon group, X and Y represent, independently from each other, a divalent group having a hetero atom and r is an integer of between 1 and 3. A reversible thermosensitive recording medium includes a support and a thermosensitive layer including the above composition.

Abstract: A reversible thermosensitive medium having a support and a thermosensitive layer, the layer comprising a composition including a coloring agent and a developer and capable of assuming a colored state and a discolored state depending upon the thermal hysteresis thereof. The developer is a phenol compound represented by the formula: ##STR1## wherein n is an integer of between 1 and 3, X represents a divalent group having a nitrogen atom or an oxygen atom, R.sup.1 represents a substituted or non-substituted aliphatic hydrocarbon group having at least two carbon atoms and R.sup.2 represents a hydrocarbon group. A reversible thermosensitive recording medium has a thermosensitive recording layer containing the above composition.

Abstract: A thermally reversible color forming composition which includes an electron-donating chromophoric compound and an electron-accepting compound, by which formation and deletion of a color image may be carried out by adjusting thermal energy applied to the composition, wherein the electron-accepting compound is a carboxylic acid compound having the following general formula (1):R.sub.1 --X--R.sub.2 --COOH (1)in which, X represents a divalent group having at least one hetero atom, R.sub.1 represents a hydrocarbon group having at least one hetero atom, R.sub.2 represents an aliphatic hydrocarbon group, which may be substituted and whose principle chain contains less than 6 carbon atoms.