Abstract: The invention relates to a process for the preparation of compounds having at least one —CF2O— bridge in the molecule, which comprises initially reacting a bis(alkylthio)carbenium salt with a compound containing at least one hydroxyl group in the presence of a base followed by oxidative fluorination, preferably in situ, with a fluorinating agent and an oxidizing agent to form the compound having at least one —CF2O— bridge in the molecule.

Abstract: The invention relates to a liquid-crystalline medium based on a mixture of polar compounds having positive dielectric anisotropy, characterized in that it comprises one or more compounds of the general formula I in which R1 and R2 are as defined herein.

Abstract: R1—(A1)m—Z1—A2—(Z2—A3)n—W—SiXaYbZc  I in which R1, A1, A2, A3, Z1, R1, Z2, W, X, Y, Z, m, n, a, b and c are as defined below, can be used to produce homeotropic alignment of liquid-crystalline phases on surfaces.

Abstract: Fluorocyclohexene derivatives of formula I R1—(A1—Z1)n—A—(Z2—A2)m—Z3—B—(Z4—A3)p—R2  I, in which n, m, p, R1, R2, Z1, Z2, Z3, Z4, A1, A2, A3, A and B are as defined herein, are suitable for use in liquid crystal mediums. Also, difluorocyclohexanes of formula III R3—A*—(Z6—A7)m—Z7—Qr—R7  III, where R3, A*, Z6, A7, m, Z7, Q, r, and R4 are as defined herein, are suitable for use in liquid crystal mediums.

Abstract: Vinyldene and ethyl compounds of the formula I in which R1, R2, A1, Z1, Z2, Z3, m, n and R are as defined herein, where at least one of Z1 to Z3 is wherein L1 to L6 are each H or F and at least one of L1 to L2 is F or at least one of L3 to L6 is F, are suitable as components of liquid-crystalline media.

Abstract: The instant invention relates to liquid crystal media comprising a strongly dielectrically positive component A, preferably comprising isothiocyanate compounds, most preferably compounds of formula I, as given in the text, and a further dielectrically positive component B, preferably comprising terminally polar substituted bi- or terphenyl compounds, most preferably comprising compounds of formula II, as given in the text, further to novel isothiocyanato compounds as well as to liquid crystal displays comprising these media, in particular to PDLC display and most particular to holographic PDLC displays.

Abstract: R1—(A1)m-Z1-A2- (Z2-A3)n—W—SiXaYbZc  I

Abstract: The invention relates to novel dioxane derivatives of the formula I

Abstract: The invention relates to a liquid-crystalline medium based on a mixture of polar compounds having positive dielectric anisotropy, characterized in that it comprises one or more compounds of the general formula I 1

Abstract: The invention relates to a liquid-crystalline medium of positive dielectric anisotropy which comprises at least one mesogenic compound and at least one compound of the formula I 1

Abstract: The invention relates to a liquid-crystalline medium based on a mixture of polar compounds having positive dielectric anisotropy, characterized in that it comprises one or more compounds of the general formula I 1

Abstract: R1—(A1)m—Z1—A2—(Z2—A3)n—W—SiXaYbZc  I in which R1, A1, A2, A3, Z1, R1, Z2, W, X, Y, Z, m, n, a, b and c are as defined below, can be used to produce homeotropic alignment of liquid-crystalline phases on surfaces.

Abstract: The invention relates to a process for the preparation of cyclohexanones from the corresponding phenols by partial hydrogenation, characterized in that the reaction mixture obtained by means of the hydrogenation is treated with sulfonating agents before the isolation of the cyclohexanone.

Abstract: The invention relates to tolan derivatives of the formula I in which R1, R2, A, Z, L1, L2, L3, L4, L5, L6, Q, m and n are as defined herein.

Abstract: A liquid-crystalline medium based on a mixture of polar compounds of positive dielectric anisotropy, characterized in that it contains one or more compounds of the general formula I ##STR1## in which R, Y, A.sup.1, A.sup.2, Z.sup.1, Z.sup.2, L.sup.1 and m are as defined herein.

Abstract: Optical transducers for measuring a contaminant in a gas are disclosed, whereby said contaminant interacts with a liquid crystalline phase as a sensing element in a flow cell. According to the invention nematic crystalline phases on a orientation layer are used. Means are provided to measure or to detect changes of the refractive index of said liquid crystalline phase caused by interaction of said contaminant with said liquid crystalline phase. In preferred embodiments the means for measuring or for detecting the refractive index is a Mach-Zehnder interferometer, a grating coupler, or a device for e.g. visual detection, whereby the flow cell is placed between two linearly polarizing filters, and whereby the two axis of polarization are crossed. Furthermore optical transducers are disclosed, which contain an isotropic dopant in a liquid crystalline phase.

Abstract: The invention relates to a liquid-crystalline medium based on a mixture of polar compounds of positive dielectric anisotropy, characterized in that it contains one or more compounds of the general formula I ##STR1## in which R, A.sup.1, A.sup.2, Z.sup.1, Z.sup.2, X, L and m are as defined in Claim 1.

Abstract: Liquid-crystalline compounds of the formula I ##STR1## R is H, an alkyl or alkylene radical, Z.sup.1 and Z are each, independently of one another, --CH.sub.2 CH.sub.2 --, --CH.dbd.CH--,--C.tbd.C-- or a single bond, and one of the radicals Z.sup.1 and Z is alternatively --(CH.sub.2).sub.4 -- or --CH.dbd.CH--CH.sub.2 CH.sub.2 --,A is trans-1,4-cyclohexylene in which, in addition, one or two non-adjacent CH.sub.2 groups may be replaced by --O--,A.sup.1 is trans-1,4-cyclohexylene in which, in addition, one or two non-adjacent CH.sub.2 groups may be replaced by --O--, or is 1,4-phenylene which is unsubstituted or monosubstituted or disubstituted by fluorine and/or Cl atoms and in which, in addition, one or two CH groups may be replaced by N,W is --O--,Q is a single bond,m, o, s, r and t are as defined below,Y is F, Cl, OCF.sub.3, CHF.sub.2, OCHF.sub.2 or OCHF, and can be CF.sub.3,are suitable as components for liquid-crystalline media.

Abstract: Chiral benzene derivatives of formula I ##STR1## in which R.sup.1*, R.sup.2*, X.sup.1, X.sup.2, A.sup.1, A.sup.2, Z.sup.1, Z.sup.2, L.sup.1, L.sup.2, L.sup.3, m, n and k are as defined in claim 1, and their use as chiral dopes in liquid-crystalline media, particularly for electrooptical displays, and to electrooptical displays containing such media.

Abstract: A liquid-crystalline medium based on a mixture of polar compounds having positive dielectric anisotropy, characterized in that it comprises one or more compounds of the general formula I ##STR1## in which R, Y, L.sup.1 and L.sup.2 are as defined in claim 1.