| abstract |
2,6-Di-tert.-butylphenol derivatives of formula (I) are new. A = (Z<2>A<2>)m-(Z<1>A<1>)n; R = H, or 1-18C alkyl or 1-18C alkenyl (both optionally substituted by CN or one or more halo, and with non-neighbouring CH2 groups optionally replaced by -O-, -S-, -C(O)-, -O-C(O)-, -C(O)-O- or -CC-); A<1>, A<2> = Aa, Ab or Ac; Aa = 1,4-phenylene residue (with 1 or 2 CH optionally replaced by N), optionally substituted by one or more halo, CN and/or Me; Ab = 1,4-cyclohexenylene or 1,4-cyclohexylene (both with 1 or 2 non-neighbouring CH2 groups replaced by -O- or -S-), both optionally substituted by one or more halo, CN and/or Me; Ac = piperidin-1,4-diyl, 1,4-bicyclo(2,2,2) oxtylene (sic) or naphthalene -2,6-diyl; Z<1>, Z<2> = bond, -CO-O-, -O-CO-, -CH2O-, -OCH2-, -CH2CH2-, -CHCH- or -CC-; m, n = 0-3; m + n \-1. The compounds with A-R = 4-(1-3C alkyl)phenyl or 2-(4-methylphenyl)ethenyl (i.e. trans p-methylstyryl) are excluded. Also claimed are 1) a liquid crystal medium (LCM) containing at least two liquid crystalline compounds and at least one compound of formula (I); and 2) an electrooptical device containing the LCM. |