Abstract: Novel reaction media for electron donating and electron accepting components in colour-change compositions are described. The compound is of formula (VI); R1, and R2 are independently selected from an optionally substituted linear or branched alkyl group, alkenyl group, alkoxy group, aryl group and an alkylene aryl group having from 5 to 22 carbon atoms; X1 and X2 are independently selected from —OC(O)—, —CO2— and O; Y1, and Y2 are independently selected from hydrogen, halogen, R1, —OR1; y is independently 0 or 1; and suitably the groups R1X1— and —X2R2 are independently in the ortho or meta position. The compounds are useful in ink compositions, writing implements containing the compound and medical and industrial applications in which temperature sensitive colour change may be required.

Abstract: A temperature-indicator product comprising a visual indicator comprising a thermochromic colour-memory composition and comprising an electron-donating colouring organic compound (A), an electron-accepting colouring organic compound (B) and reaction medium compound (C). The visual indicator comprises a first portion comprising a first thermochromic colour-change composition in its lower temperature state and a second portion comprising a second thermochromic colour-change composition in its higher temperature state. The product is useful as a tamper-evident indicator or as a freeze indicator.

Abstract: A temperature-indicator product comprising a visual indicator comprising a thermochromic colour-memory composition and comprising an electron-donating colouring organic compound (A), an electron-accepting colouring organic compound (B) and reaction medium compound (C). The visual indicator comprises a first portion comprising a first thermochromic colour-change composition in its lower temperature state and a second portion comprising a second thermochromic colour-change composition in its higher temperature state. The product is useful as a tamper-evident indicator or as a freeze indicator.