Catalyst systems suitable for tetramerizing ethylene to form 1-octene may include a catalyst including a reaction product of a chromium compound and a ligand having the structure according to Formula (II). In Formula (II), A and C may be independently chosen from phosphorus, arsenic, antimony, bismuth, and nitrogen; B may be a linking group between A and C; and R.sub.1, R.sub.2, R.sub.3, and R.sub.4 may be independently chosen from a (C.sub.1-C.sub.50) hydrocarbyl or a (C.sub.1-C.sub.50) heterohydrocarbyl. The catalyst system may include a co-catalyst including a reaction product of an organoaluminum compound and an antifouling compound. The antifouling compound may include one or more quaternary salts; one or more organic acids, organic acid salts, esters, anhydrides, or combinations of these; one or more chlorinated hydrocarbons, chloro-aluminum alkyls, or combinations of these; one or more polyether alcohols; or one or more non-polymeric ethers.

Catalyst systems suitable for tetramerizing ethylene to form 1-octene may include a catalyst having a structure according to Formula (VI) or Formula (VII). In Formulas (VI) and (VII), X is a halogen, a (C.sub.2-C.sub.30) carboxylate, acetylacetonate, or a (C.sub.1-C.sub.30) hydrocarbyl; L.sub.1 is a neutral coordinating ligand; n is an integer from 0 to 6; Y is a (C.sub.6-C20)fluorine-substituted aryl, a (C.sub.6-C.sub.20)fluorine-substituted aryloxy, or a (C.sub.1-C.sub.20)fluorine-substituted alkoxy; and L∩L is a bidentate chelating ligand. The catalyst system may also include an aluminum containing agent which includes a reaction product of an organoaluminum compound and an antifouling compound. The antifouling compound may include one or more chlorinated hydrocarbons, chloro-aluminum alkyls, or combinations of these.

Provided is a method capable of industrially efficiently producing acetic acid yielding a good potassium permanganate test result, without costing much. In the acetic acid production method, (1) by-produced acetaldehyde is industrially advantageously removed from a process stream, and (2) a crotonaldehyde concentration in an acetic acid stream from a light ends column is controlled to a specific level or lower, and/or a reflux ratio at a second distillation column is controlled to 0.1 or more. In addition, (3) the method includes the step of subjecting at least one of an aqueous phase and an organic phase of a light ends column overhead condensate to distillation in a crotonaldehyde-removing column; the light ends column is operated at a reflux ratio of 2 or more (when the aqueous phase is refluxed); and the crotonaldehyde-removing column is operated so as to meet a specific condition(s).

The present invention relates to an improved synthesis of malathion. The presence of an acid facilitates the reaction between O,O-dimethyldithiophosphoric acid (O,O-DMDTPA) and maleate and leads to excellent product yield in shorter reaction time with fewer impurities.

The present invention may provide an asymmetric hydrogenation catalyst capable of resolving enantiomers with excellent enantioselectivity from a carbon-carbon double bond-containing compound. The catalyst according to one embodiment of the present invention includes: an iridium cation; and a ligand bonded to the iridium cation.

Catalyst systems suitable for tetramerizing ethylene to form 1-octene may include a catalyst having a structure according to Formula (VI) or Formula (VII). In Formulas (VI) and (VII), X is a halogen, a (C.sub.2-C.sub.30) carboxylate, acetylacetonate, or a (C.sub.1-C.sub.30) hydrocarbyl; L.sub.1 is a neutral coordinating ligand; n is an integer from 0 to 6; Y is a (C.sub.6-C20)fluorine-substituted aryl, a (C.sub.6-C.sub.20)fluorine-substituted aryloxy, or a (C.sub.1-C.sub.20)fluorine-substituted alkoxy; and L∩L is a bidentate chelating ligand. The catalyst system may also include an aluminum containing agent which includes a reaction product of an organoaluminum compound and an antifouling compound. The antifouling compound may include one or more chlorinated hydrocarbons, chloro-aluminum alkyls, or combinations of these.

Catalyst systems suitable for tetramerizing ethylene to form 1-octene may include a catalyst including a reaction product of a chromium compound and a ligand having the structure according to Formula (II). In Formula (II), A and C may be independently chosen from phosphorus, arsenic, antimony, bismuth, and nitrogen; B may be a linking group between A and C; and R.sub.1, R.sub.2, R.sub.3, and R.sub.4 may be independently chosen from a (C.sub.1-C.sub.50) hydrocarbyl or a (C.sub.1-C.sub.50) heterohydrocarbyl. The catalyst system may include a co-catalyst including a reaction product of an organoaluminum compound and an antifouling compound. The antifouling compound may include one or more quaternary salts; one or more organic acids, organic acid salts, esters, anhydrides, or combinations of these; one or more chlorinated hydrocarbons, chloro-aluminum alkyls, or combinations of these; one or more polyether alcohols; or one or more non-polymeric ethers.

According to one embodiment, a catalyst system that reduces polymeric fouling may include at least one chromium compound, at least one aluminum compound, and at least one antifouling agent or a derivative thereof. The antifouling agent may have a structure including a central aluminum molecule bound to an R1 group, bound to an R2 group, and bound to an R3 group. One or more of the chemical groups R1, R2, and R3 may be antifouling groups having the structure —O((CH.sub.2).sub.nO).sub.mR4, a phosphonium or phosphonium salt, a sulfonate or sulfonate salt, a sulfonium or sulfonium salt, an ester, an anhydride, a polyether, or a long-chained amine-capped compound, where n is an integer from 1 to 20, m is an integer from 1 to 100, and R4 is a hydrocarbyl group. The chemical groups R1, R2, or R3 that do not include an antifouling group, if any, may be hydrocarbyl groups.

The subject invention pertains to a method of halogenating phenols, yielding a range of halogenated phenols with enantiomeric ratio of up to 99.5:0.5. In certain embodiments, the subject invention pertains to a method of asymmetric halogenation of bisphenol, yielding a range of chiral bisphenol ligands. The novel chiral bisphenols are potent privileged catalyst cores that can be applied to the preparation of ligands for various catalytic asymmetric reactions. The catalyst library can easily be accessed because late-stage modification of the scaffold can readily be executed through cross-coupling of the halogen handles on the bisphenols.

An object is to provide a method for producing a compound which is useful as a synthetic intermediate for an active pharmaceutical ingredient of an antidiabetic drug or the like in an industrially inexpensive and efficient manner, and the present invention can achieve the object by reducing a compound (2) represented by the following formula (2):

##STR00001## wherein R.sub.1, Ar, n and X are as mentioned herein in the presence of a titanium compound by using a reducing agent to produce a compound (1) represented by the following formula (1):

##STR00002## wherein R.sub.1, Ar and n are the same as defined above.