The present invention relates to a method for preparing a modified conjugated diene-based polymer, and more particularly, provides a method for preparing a modified conjugated diene-based polymer including a step of polymerizing a conjugated diene-based monomer in the presence of an organometal compound in a hydrocarbon solvent to prepare an active polymer which is coupled with an organometal (S1); and a step of reacting or coupling the active polymer prepared in step (S1) with a modifier (S2), wherein step (S1) is continuously performed in two or more polymerization reactors, and a polymerization conversion ratio in a first reactor among the polymerization reactors is 50% or less.

The present invention relates to a method for preparing a modified conjugated diene-based polymer, and more particularly, provides a method for preparing a modified conjugated diene-based polymer including a step of polymerizing a conjugated diene-based monomer in the presence of an organometal compound in a hydrocarbon solvent to prepare an active polymer which is coupled with an organometal (S1); and a step of reacting or coupling the active polymer prepared in step (S1) with a modifier (S2), wherein step (S1) is continuously performed in two or more polymerization reactors, and a polymerization conversion ratio in a first reactor among the polymerization reactors is 50% or less.

An acetylacetone derivative is useful for capturing a metal element by complexation. A convenient and very versatile synthesis method can be used to synthesize the derivative. The derivative can have the following formula: ##STR00001##

An acetylacetone derivative is useful for capturing a metal element by complexation. A convenient and very versatile synthesis method can be used to synthesize the derivative. The derivative can have the following formula: ##STR00001##

The present invention relates to a fluorine-containing diene compound represented by the following formula I, and to a polymer thereof. In the formula, each of R.sup.1 to R.sup.7 is independently a hydrogen atom, a chlorine atom, a fluorine atom, or an alkyl group having a carbon number of 1 to 5 which may be substituted by a fluorine atom, k is 0 or 1, and at least one of R.sup.1 to R.sup.7 is a hydrogen atom.

##STR00001##

Provided is a chloroprene-based polymer having an industrially applicable sufficient molecular weight and capable of obtaining a vulcanized rubber excellent in durability and fatigue endurance and an adhesive excellent in layer separation resistance. A chloroprene-based polymer having a number average molecular weight Mn of 150000 to 300000 and comprising a functional group of a structure represented by the general formula (1) or (2) below:

##STR00001##

(wherein in the general formula (1), R1 shows hydrogen, chlorine, a substituted or unsubstituted alkyl group, a substituted or unsubstituted alkenyl group, a substituted or unsubstituted aryl group, or a substituted or unsubstituted heterocyclyl group.)

According to a method for producing a perfluoroalkadiene compound represented by general formula (1): CF.sub.2CF(CF.sub.2).sub.n-4CFCF.sub.2 (1), wherein n is an integer of 4 or more, the method comprising a reaction step of adding a nitrogen-containing compound to a solution of a compound represented by general formula (2): X.sup.1CF.sub.2CFX.sup.2(CF.sub.2).sub.n-4CF.sub.2X.sup.1 (2), wherein n is the same as above, X.sup.1 is the same or different and is a halogen atom other than fluorine, and X.sup.2 is a halogen atom, the perfluoroalkadiene compound can be obtained at a high yield.

Provided are a rubber composition for pneumatic tires with excellent fluidity and excellent degradation resistance, and a pneumatic tire formed from the rubber composition. The present invention relates to a rubber composition for pneumatic tires containing a rubber component including a halogenated butyl rubber, and an organic peroxide.

Provided are a rubber composition for pneumatic tires with excellent fluidity and excellent degradation resistance, and a pneumatic tire formed from the rubber composition. The present invention relates to a rubber composition for pneumatic tires containing a rubber component including a halogenated butyl rubber, and an organic peroxide.

Provided are a rubber composition for pneumatic tires which is excellent in adhesion, sealing performance, fluidity, and processability, and a pneumatic tire formed from the rubber composition. The present invention relates to a rubber composition for pneumatic tires containing, per 100 parts by mass of a rubber component including a butyl-based rubber: 100 to 400 parts by mass of a liquid polymer; 1 to 40 parts by mass of an organic peroxide; and 1 to 40 parts by mass of a crosslinking activator.