The present invention provides a crosslinking agent which can improve crosslinked fluoroelastomer high-temperature vapor resistance and a crosslinked fluoroelastomer having improved high-temperature vapor resistance. The present invention provides a compound having a structure represented by the following formula (1) (in the formula, R.sup.1 to R.sup.6 are each a hydrogen atom, a substituent, or a leaving group, and two or more of R.sup.1 to R.sup.6 are leaving groups; R.sup.a to R.sup.c are each a hydrogen atom or a substituent; and n is an integer from 2 to 5).

##STR00001##

The present invention provides a crosslinking agent which can improve crosslinked fluoroelastomer high-temperature vapor resistance and a crosslinked fluoroelastomer having improved high-temperature vapor resistance. The present invention provides a compound having a structure represented by the following formula (1) (in the formula, R.sup.1 to R.sup.6 are each a hydrogen atom, a substituent, or a leaving group, and two or more of R.sup.1 to R.sup.6 are leaving groups; R.sup.a to R.sup.c are each a hydrogen atom or a substituent; and n is an integer from 2 to 5).

##STR00001##

A fluorine-containing ether compound according to the present invention is expressed by the following formula (1) or the following formula (2):

Q.sup.1{—(R.sup.f12).sub.m2—O—(R.sup.f11O).sub.m1-A.sup.1}.sub.n1  Formula (1)

{A.sup.1-(OR.sup.f11).sub.m1—O—(R.sup.f12).sub.m2-}.sub.n2Q.sup.2-[(R.sup.f12).sub.m2—O—(R.sup.f11O).sub.m1—(R.sup.f12).sub.m2-Q.sup.3].sub.p—(R.sup.f12).sub.m2—O—(R.sup.f11O).sub.m1—(R.sup.f12).sub.m2-Q.sup.2-{(R.sup.f12).sub.m2—O—(R.sup.f11O).sub.m1-A.sup.1}.sub.n2  Formula (2),

wherein Q.sup.1, Q.sup.2, Q.sup.3, R.sup.f11, R.sup.f12, A.sup.1, n1, n2, m1, m2, and p are as described in the specification.

The present application provides, among other things, compounds and methods for metathesis reactions. In some embodiments, the present disclosure provides methods for preparing alkenyl halide with regioselectivity and/or stereoselectivity. In some embodiments, the present disclosure provides methods for preparing alkenyl halide with regioselectivity and Z-selectivity. In some embodiments, the present disclosure provides methods for preparing alkenyl halide with regioselectivity and E-selectivity. In some embodiments, provided technologies are particularly useful for preparing alkenyl fluorides. In some embodiments, a provided compound useful for metathesis reactions has the structure of formula II-a. In some embodiments, a provided compound useful for metathesis reactions has the structure of formula II-b.

The present application provides, among other things, compounds and methods for metathesis reactions. In some embodiments, the present disclosure provides methods for preparing alkenyl halide with regioselectivity and/or stereoselectivity. In some embodiments, the present disclosure provides methods for preparing alkenyl halide with regioselectivity and Z-selectivity. In some embodiments, the present disclosure provides methods for preparing alkenyl halide with regioselectivity and E-selectivity. In some embodiments, provided technologies are particularly useful for preparing alkenyl fluorides. In some embodiments, a provided compound useful for metathesis reactions has the structure of formula II-a. In some embodiments, a provided compound useful for metathesis reactions has the structure of formula II-b.

A composition including a compound having structural formula (I): R.sub.f is a linear or branched perfluoroalkyl group having 1-3 atoms; n is 0-2; x is 1-3; and R.sub.f′ and R.sub.f″ are (i) independently, a linear or branched perfluoroalkyl group having 1-8 carbon atoms; or (ii) are bonded together to form a ring structure having 4-8 carbon atoms. The composition further includes a hydrocarbon contaminant.

##STR00001##

A composition including a compound having structural formula (I): R.sub.f is a linear or branched perfluoroalkyl group having 1-3 atoms; n is 0-2; x is 1-3; and R.sub.f′ and R.sub.f″ are (i) independently, a linear or branched perfluoroalkyl group having 1-8 carbon atoms; or (ii) are bonded together to form a ring structure having 4-8 carbon atoms. The composition further includes a hydrocarbon contaminant.

##STR00001##

A problem is to provide a liquid crystal compound satisfying at least one physical property such as high stability to heat and light, a high clearing point (or high maximum temperature), a low minimum temperature of a liquid crystal phase, small viscosity, suitable optical anisotropy, large dielectric anisotropy, a suitable elastic constant and excellent compatibility with other liquid crystal compounds, a liquid crystal composition containing the compound and a liquid crystal display device including the composition. A solution is a compound represented by formula (1). ##STR00001## In which, R.sup.1 is alkyl having 1 to 10 carbons or the like; Z.sup.1, Z.sup.2 and Z.sup.3 are independently a single bond, —COO—, —OCH.sub.2—, —CF.sub.2O— or the like, and at least one of Z.sup.1, Z.sup.2 and Z.sup.3 is —CF.sub.2O—; X.sup.1 is hydrogen, fluorine, —CF.sub.3 or —OCF.sub.3; and L.sup.1, L.sup.2, L.sup.3 and L.sup.4 are independently hydrogen, fluorine or chlorine.

A problem is to provide a liquid crystal compound satisfying at least one physical property such as high stability to heat and light, a high clearing point (or high maximum temperature), a low minimum temperature of a liquid crystal phase, small viscosity, suitable optical anisotropy, large dielectric anisotropy, a suitable elastic constant and excellent compatibility with other liquid crystal compounds, a liquid crystal composition containing the compound and a liquid crystal display device including the composition. A solution is a compound represented by formula (1). ##STR00001## In which, R.sup.1 is alkyl having 1 to 10 carbons or the like; Z.sup.1, Z.sup.2 and Z.sup.3 are independently a single bond, —COO—, —OCH.sub.2—, —CF.sub.2O— or the like, and at least one of Z.sup.1, Z.sup.2 and Z.sup.3 is —CF.sub.2O—; X.sup.1 is hydrogen, fluorine, —CF.sub.3 or —OCF.sub.3; and L.sup.1, L.sup.2, L.sup.3 and L.sup.4 are independently hydrogen, fluorine or chlorine.

The invention provides a liquid crystal compound satisfying at least one of physical properties such as a high stability to heat or light, a high clearing point (or a high maximum temperature), a low minimum temperature of a liquid crystal phase, a small viscosity, a suitable optical anisotropy, a small dielectric anisotropy, a suitable elastic constant and a good compatibility with other liquid crystal compounds, a liquid crystal composition including this compound, and a liquid crystal display device containing this composition. The invention provdes a compound represented by formula (1):

##STR00001##

where R.sup.1 and R.sup.2 is alkyl having 1 to 20 carbons or the like; one of L.sup.1 and L.sup.2 is both hydrogens, and the other is both fluorines; Z.sup.1 and Z.sup.2 are independently a single bond, —COO—, —OCO—, —OCH.sub.2—, —CH.sub.2O—, —CF.sub.2O—, —OCF.sub.2—, —CH.sub.2CH.sub.2—, —CH═CH—, —C≡C— or the like.