Organic compounds -- part of the class 532-570 series – Organic compounds – Carboxylic acid esters
Reexamination Certificate
2001-09-20
2004-05-18
Killos, Paul J. (Department: 1625)
Organic compounds -- part of the class 532-570 series
Organic compounds
Carboxylic acid esters
C560S114000, C560S204000, C560S233000
Reexamination Certificate
active
06737542
ABSTRACT:
The present invention relates to a process for the carbonylation of conjugated dienes, whereby a conjugated diene is reacted with carbon monoxide and a hydroxyl group containing compound in the presence of a catalyst system including a source of palladium cations, a phosphorus-containing ligand and a source of anions. In particular it relates to the preparation of alkyl pentenoates and/or adipates from 1,3-butadiene and derivatives thereof.
U.S. Patent publication No. 5,495,041 describes a process for the preparation of a pentenoate ester by carbonylation of butadiene in the presence of carbon monoxide, alcohol and a catalyst system comprising palladium, pentenoic acid and a phosphorus-containing ligand. The phosphorus-containing ligand can be a monodentate or multidentate phosphorus-containing ligand or a mixture thereof. Preferably a monodentate phosphorus-containing ligand is used to obtain a high selectivity. The examples disclose the use of 1,4-bis(diphenyl-phoshino) butane and triphenyl phosphine as phosphorus-containing ligands. The molar ratio of butadiene to palladium is according to this publication, preferably less than 20:1. A disadvantage is that this catalyst system has only a moderate activity.
European patent publication No. 0198521 describes a process for preparing carboxylic di-esters, or carboxylic di-acids by the reaction of a conjugated diene with carbon monoxide and an alkanol or water in the presence of an aprotic solvent and a dissolved catalyst system comprising a divalent palladium compound, a triaryl phosphine and hydrogen chloride. The catalyst system may further comprise a bidentate phosphorus-containing ligand, i.e. a bis(diaryl-phoshino)alkane. In its examples it is illustrated that the process can also be used for the preparation of mono-esters. The conversion of 1,3-butadiene to carboxylic diesters or to mono-esters is performed in one step. Because, at least one mole of hydrogen chloride per atom of trivalent phosphorus present in the catalytic system is considered necessary, supplementary, cost-increasing measures are required to avoid corrosion. Examples disclose that the molar ratio of conjugated diene to palladium is about 115:1.
Object of the present invention, is to provide an improved process in terms of catalyst activity for carbonylation of conjugated dienes.
An improved process has now been found for the selective conversion of conjugated dienes such as 1,3-butadiene, with a high conversion rate, in the presence of a specific catalyst system.
The present invention therefore provides a process for the carbonylation of conjugated dienes, whereby a conjugated diene is reacted with carbon monoxide and a hydroxyl group containing compound in the presence of a catalyst system based on:
(a) a source of palladium cations,
(b) a phosphorus-containing ligand
(c) a source of anions, wherein the phosphorus-containing ligand is a ligand having the general formula I
X
1
—R—X
2
(I)
wherein X
1
and X
2
represent a substituted or non-substituted cyclic group with at least 5 ring atoms, of which one is a phosphorus atom, and R represents a bivalent organic bridging group, connecting both phosphorus atoms, containing from 1 to 4 atoms in the bridge.
This specific catalyst system has an unexpectedly high activity, which allows for molar ratios well over 200:1 and suitably well over 300:1 of conjugated diene to palladium to be used, whilst still obtaining high selectivities to the desired product(s). High conversion rates are achieved without the necessity of the presence of halides, thus allowing cheaper types of steel for the reactor installations. A further advantage is that in one step simultaneously both mono-esters and di-esters, and in particular mono-esters and di-esters of butadiene, such as methyl-pentenoate and dimethyl adipate, can be prepared.
A catalyst system comprising palladium cations, a carboxylic acid and 1,2-bis(cyclooctylenephosphino)ethane as the phosphorus-containing ligand is described in PCT patent publication 9703943 for the carbonylation of ethene.
However, the process of the present invention is specifically directed to the carbonylation of conjugated dienes, which show specific reaction characteristics when compared to olefins in general. Conjugated dienes contain at least two conjugated double bonds in the molecule. By conjugation is meant that the location of the &pgr;-orbital is such that it can overlap other orbitals in the molecule. Thus, the effects of compounds with at least two conjugated double bonds are often different in several ways from those of compounds with no conjugated bonds. It is generally acknowledged that the carbonylation of conjugated dienes comprises more difficulties than that of a mono-olefin. For example, in European patent publication No. 0495548, relating to the carbonylation of olefins with a catalyst system obtainable by combining a group VIII metal with a bidentate phosphorus-containing ligand, i.e. a bis(di(tertiary alkyl)-phoshino)alkane, it is stated that diolefins with more than one unsaturated double bond may be used, however, in particular those wherein the double bonds are non-conjugated.
The process of the present invention can advantageously be used to prepare mono-esters and/or diesters in one step. By optimising reaction conditions such as the residence time, the pressure, the temperature, the amount of hydroxyl group containing compound, the source of anions and specific type of ligand, the process can be made more selective by the skilled person to either mono-esters or diesters as will be described in more detail below.
Preferred hydroxyl group containing compounds in the process of the invention are alkanols with 1 to 20, more preferably with 1 to 6 carbon atoms per molecule and alkanediols with 2-20, more preferably 2 to 6 carbon atoms per molecule. Suitable alkanols in the process of the invention include methanol, ethanol, propanol, iso-propanol, butanol, iso-butanol, tert.butanol, pentanol, hexanol, cyclohexanol and phenol. Preferably methanol or ethanol is used as a hydroxyl group containing compound. Methanol is especially preferred as a hydroxyl group containing compound.
The conjugated diene preferably is a conjugated diene having from 4 to 20, more preferably from 4 to 8 carbon atoms per molecule. The conjugated diene can be substituted or non-substituted. Most preferably, the conjugated diene is non-substituted 1,3-butadiene.
For example when methanol is used as a hydroxyl group containing compound in the carboxylation process of 1,3-butadiene enables the production of methyl-pentenoate and/or dimethyl adipate and preferably both. Dimethyl adipate is an intermediate compound in the preparation of adipic acid, an intermediate compound to prepare Nylon 6,6. Methyl-pentenoate is an important intermediate in the production process of &egr;-caprolactam. For the preparation of &egr;-caprolactam, methyl-pentenoate is hydroformylated to methyl formylvalerate, which after reductive amination and cyclisation forms &egr;-caprolactam. &egr;-Caprolactam is a starting material in the manufacture of Nylon 6 fibres or engineering plastics. Hydroformylation, reductive amination and cyclisation can be performed in any manner known to a person skilled in the art. Suitable processes are given in PCT application No. 95/0625 and Japanese patent application No. 25351/66A.
The process of the present invention is therefore particularly advantageous when there is a need to supply both methyl-pentenoate, as an intermediate for preparation of Nylon 6, as well as dimethyl adipate, as an intermediate for the preparation of Nylon 6,6. The amount prepared of each intermediate can be varied, in proportion to the commercial need, by varying the reaction conditions.
The person with average skill in the art will further realise that the process of the present invention can also be used to prepare carboxylic mono-acids and/or carboxylic diacids. Carboxylic mono-acids and/or carboxylic diacids are prepared by reacting conjugated dienes with carbon monoxide and using water as a hydroxyl grou
Drent Eit
Jager Willem Wabe
Killos Paul J.
Reyes Hector M.
Shell Oil Company
LandOfFree
Process for the carbonylation of conjugated dienes does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Process for the carbonylation of conjugated dienes, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Process for the carbonylation of conjugated dienes will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-3216029