Systems and methods for recovering cyclopentadiene and/or isoprene from a mixture comprising C.sub.5 hydrocarbons are disclosed. A C.sub.5 mixture comprising cyclopentadiene and/or isoprene is flowed into a dimerization unit to form dimers. The dimers are then separated from the unreacted C.sub.5 hydrocarbons. The separated dimers are monomerized to form a stream comprising cyclopentadiene and/or isoprene, which is subsequently separated to form a first product stream comprising primarily isoprene and a second product stream comprising primarily cyclopentadiene.

Systems and methods for recovering cyclopentadiene and/or isoprene from a mixture comprising C.sub.5 hydrocarbons are disclosed. A C.sub.5 mixture comprising cyclopentadiene and/or isoprene is flowed into a dimerization unit to form dimers. The dimers are then separated from the unreacted C.sub.5 hydrocarbons. The separated dimers are monomerized to form a stream comprising cyclopentadiene and/or isoprene, which is subsequently separated to form a first product stream comprising primarily isoprene and a second product stream comprising primarily cyclopentadiene.

A metal cyclopentadienyl complex has the formula:

##STR00001##

wherein m≥0; M is a Group I, II or III main group metal, alkali or transition metal; C.sub.5H.sub.4 represents a Cp ring where two hydrogens are substituted by M and R(F).sub.m; R(F).sub.m is connected to any one of the carbon atoms of the Cp and selected from a hydrocarbyl, fluorohydrocarbyl, silyl group [SiR′.sub.3], or amino group [—NR.sup.1R.sup.2]. The metal cyclopentadienyl complexes include Li(C.sub.5H.sub.4-2-C.sub.5H.sub.11) (CAS No: 2413046-23-6), K(C.sub.5H.sub.4-2-C.sub.5H.sub.11), Na(C.sub.5H.sub.4-2-C.sub.5H.sub.11), K(C.sub.5H.sub.4-1-F—C.sub.4H.sub.10), K(C.sub.5H.sub.4-1,1,1-3F—C.sub.4H.sub.6), Li(C.sub.5H.sub.4-2-C.sub.4H.sub.9), or In(C.sub.5H.sub.4-2-C.sub.5H.sub.11) (CAS No.: 2364634-67-1).

A mono-substituted cyclopentadiene has the formula:

##STR00002##

wherein m≥0; C.sub.5H.sub.5 represents the Cp ring where one hydrogen is substituted R(F).sub.m; R(F).sub.m is connected to any one of the carbon atoms of the Cp and selected from a hydrocarbyl, fluorohydrocarbyl, silyl group [SiR′.sub.3], or amino group [—NR.sup.1R.sup.2]. The mono-substituted cyclopentadienes include C.sub.5H.sub.5-1-F—C.sub.4H.sub.10, C.sub.5H.sub.5-2-C.sub.5H.sub.11, C.sub.5H.sub.5-2-C.sub.4H.sub.9, or C.sub.5H.sub.5-1,1,1-3F—C.sub.4H.sub.6.

A metal cyclopentadienyl complex has the formula:

##STR00001##

wherein m≥0; M is a Group I, II or III main group metal, alkali or transition metal; C.sub.5H.sub.4 represents a Cp ring where two hydrogens are substituted by M and R(F).sub.m; R(F).sub.m is connected to any one of the carbon atoms of the Cp and selected from a hydrocarbyl, fluorohydrocarbyl, silyl group [SiR′.sub.3], or amino group [—NR.sup.1R.sup.2]. The metal cyclopentadienyl complexes include Li(C.sub.5H.sub.4-2-C.sub.5H.sub.11) (CAS No: 2413046-23-6), K(C.sub.5H.sub.4-2-C.sub.5H.sub.11), Na(C.sub.5H.sub.4-2-C.sub.5H.sub.11), K(C.sub.5H.sub.4-1-F—C.sub.4H.sub.10), K(C.sub.5H.sub.4-1,1,1-3F—C.sub.4H.sub.6), Li(C.sub.5H.sub.4-2-C.sub.4H.sub.9), or In(C.sub.5H.sub.4-2-C.sub.5H.sub.11) (CAS No.: 2364634-67-1).

A mono-substituted cyclopentadiene has the formula:

##STR00002##

wherein m≥0; C.sub.5H.sub.5 represents the Cp ring where one hydrogen is substituted R(F).sub.m; R(F).sub.m is connected to any one of the carbon atoms of the Cp and selected from a hydrocarbyl, fluorohydrocarbyl, silyl group [SiR′.sub.3], or amino group [—NR.sup.1R.sup.2]. The mono-substituted cyclopentadienes include C.sub.5H.sub.5-1-F—C.sub.4H.sub.10, C.sub.5H.sub.5-2-C.sub.5H.sub.11, C.sub.5H.sub.5-2-C.sub.4H.sub.9, or C.sub.5H.sub.5-1,1,1-3F—C.sub.4H.sub.6.

Inhibitor compositions for abating undesirable polymerization in the vapor space during purification of reactive vinylic monomers are provided. The polymerization inhibitor compositions include at least a first inhibitor compound having a stable nitroxide radical and a second inhibitor including phenylenediamine. Methods of inhibiting the polymerization of monomers in the vapor-space using the compositions of the disclosure are also provided.

Inhibitor compositions for abating undesirable polymerization in the vapor space during purification of reactive vinylic monomers are provided. The polymerization inhibitor compositions include at least a first inhibitor compound having a stable nitroxide radical and a second inhibitor including phenylenediamine. Methods of inhibiting the polymerization of monomers in the vapor-space using the compositions of the disclosure are also provided.

Inhibitor compositions for abating undesirable polymerization during processing of hydrocarbon stream laden with reactive vinylic monomers are provided. The polymerization inhibitor compositions include at least a first inhibitor compound having a stable nitroxide radical and a second inhibitor including phenylenediamine. Methods of inhibiting the polymerization of monomers using the compositions of the disclosure are also provided. The methods of inhibiting polymerization of monomers include a step of adding a composition of the disclosure to the monomer. In some instances, the monomer is an ethylenically unsaturated monomer. Such ethylenically unsaturated monomers include, but are not limited to, vinyl acetate, acrylonitrile, acrylates, methacrylates, 1,3-butadiene, styrene, isoprene, (meth)acrylic acid, and combinations thereof. Methods of preparing the polymerization inhibitors and compositions of the disclosure are also provided.

Inhibitor compositions for abating undesirable polymerization during processing of hydrocarbon stream laden with reactive vinylic monomers are provided. The polymerization inhibitor compositions include at least a first inhibitor compound having a stable nitroxide radical and a second inhibitor including phenylenediamine. Methods of inhibiting the polymerization of monomers using the compositions of the disclosure are also provided. The methods of inhibiting polymerization of monomers include a step of adding a composition of the disclosure to the monomer. In some instances, the monomer is an ethylenically unsaturated monomer. Such ethylenically unsaturated monomers include, but are not limited to, vinyl acetate, acrylonitrile, acrylates, methacrylates, 1,3-butadiene, styrene, isoprene, (meth)acrylic acid, and combinations thereof. Methods of preparing the polymerization inhibitors and compositions of the disclosure are also provided.

Polymerization inhibitor compositions are provided. The polymerization inhibitor compositions include at least a first inhibitor compound including a hydroxylamine, a second inhibitor including phenylenediamine, and a third inhibitor including a benzoquinone or naphthoquinone. Methods of inhibiting the polymerization of monomers using the compositions of the disclosure are also provided. The methods of inhibiting polymerization of monomers include a step of adding a composition of the disclosure to the monomer. In some instances, the monomer is an ethylenically unsaturated monomer. Such ethylenically unsaturated monomers include, but are not limited to, vinyl acetate, acrylonitrile, acrylates, methacrylates, 1,3-butadiene, styrene, isoprene, (meth)acrylic acid, and combinations thereof. Methods of preparing the polymerization inhibitors and compositions of the disclosure are also provided.

Polymerization inhibitor compositions are provided. The polymerization inhibitor compositions include at least a first inhibitor compound including a hydroxylamine, a second inhibitor including phenylenediamine, and a third inhibitor including a benzoquinone or naphthoquinone. Methods of inhibiting the polymerization of monomers using the compositions of the disclosure are also provided. The methods of inhibiting polymerization of monomers include a step of adding a composition of the disclosure to the monomer. In some instances, the monomer is an ethylenically unsaturated monomer. Such ethylenically unsaturated monomers include, but are not limited to, vinyl acetate, acrylonitrile, acrylates, methacrylates, 1,3-butadiene, styrene, isoprene, (meth)acrylic acid, and combinations thereof. Methods of preparing the polymerization inhibitors and compositions of the disclosure are also provided.