Diastereomer mixture comprising diastereomers of the formulae (I.1) and (I.2) ##STR00001##
where
R.sup.2, R.sup.4 are each independently selected from (C.sub.1-C.sub.12)-alkyl, (C.sub.3-C.sub.12)-cycloalkyl, (C.sub.3-C.sub.12)-heterocycloalkyl, (C.sub.6-C.sub.20)-aryl;
the R.sup.1, R.sup.3 radicals are each a (C.sub.3-C.sub.20)-heteroaryl radical. The invention further relates to Pd complex mixtures comprising the diastereomers according to the invention, and to the use thereof in an alkoxycarbonylation process.

The present invention provides a process for producing butadiene by oxidative dehydrogenation of butylene, comprising: a reaction stage, wherein a multi-stage adiabatic fixed bed in series is used, wherein butylene, oxygen-comprising gas and water are reacted in the presence of a catalyst in each stage of the adiabatic fixed bed with the first stage of the adiabatic fixed bed being further separately fed a diluent, being nitrogen and/or carbon dioxide, and the molar ratio between this separately fed diluents and the oxygen of all the oxygen-comprising gases fed in the subsequent stage(s) of the adiabatic fixed bed being controlled, wherein the oxygen-comprising gas is air, oxygen-enriched air or oxygen, and at least one of all the oxygen-comprising gases fed in the subsequent stage(s) of the adiabatic fixed bed is oxygen-enriched air having a specific oxygen concentration or oxygen; and a post treatment stage, wherein the effluent from the last stage of the adiabatic fixed bed is treated to obtain a product butadiene. The present invention has an advantage that the whole process is with reduced total energy consumption.

Butadiene is made from a butene rich feed by passing a superheated butene rich feed including superheated steam and oxygen at a temperature of at least about 343 C. (650 F.) over a catalyst bed having a depth of over about 69 cm (27 inches) of granules of ferritic oxidative dehydrogenation catalyst. Inlet conditions being controlled such that the oxidative dehydrogenation reactions initially occur in the lower most layers of catalyst. Process control includes monitoring the temperature throughout the bed and increasing the inlet temperature in response to a drop in the temperature in the active layer, when the active layer of oxidative dehydrogenation catalyst begins to become deactivated so that the reaction zone moves upwardly in the oxidative dehydrogenation bed.

Diastereomer mixture comprising diastereomers of the formulae (I.1) and (I.2)

##STR00001##

where R.sup.2, R.sup.4 are each independently selected from (C.sub.1-C.sub.12)-alkyl, (C.sub.3-C.sub.12)-cycloalkyl, (C.sub.3-C.sub.12)-heterocycloalkyl, (C.sub.6-C.sub.20)-aryl; the R.sup.1, R.sup.3 radicals are each a (C.sub.3-C.sub.20)-heteroaryl radical; R.sup.1, R.sup.3 may each independently be substituted by one or more substituents selected from (C.sub.1-C.sub.12)-alkyl, (C.sub.3-C.sub.12)-cycloalkyl, (C.sub.3-C.sub.12)-heterocycloalkyl, O(C.sub.1-C.sub.12)-alkyl, O(C.sub.1-C.sub.12)-alkyl-(C.sub.6-C.sub.20)-aryl, O(C.sub.3-C.sub.12)-cycloalkyl, S(C.sub.1-C.sub.12)-alkyl, S(C.sub.3-C.sub.12)-cycloalkyl, COO(C.sub.1-C.sub.12)-alkyl, COO(C.sub.3-C.sub.12)-cycloalkyl, CONH(C.sub.1-C.sub.12)-alkyl, CONH(C.sub.3-C.sub.12)-cycloalkyl, CO(C.sub.1-C.sub.12)-alkyl, CO(C.sub.3-C.sub.12)-cycloalkyl, N[(C.sub.1-C.sub.12)-alkyl].sub.2, (C.sub.6-C.sub.20)-aryl, (C.sub.6-C.sub.20)-aryl-(C.sub.1-C.sub.12)-alkyl, (C.sub.6-C.sub.20)-aryl-O(C.sub.1-C.sub.12)-alkyl, (C.sub.3-C.sub.20)-heteroaryl, (C.sub.3-C.sub.20)-heteroaryl-(C.sub.1-C.sub.12)-alkyl, (C.sub.3-C.sub.20)-heteroaryl-O(C.sub.1-C.sub.12)-alkyl, COOH, OH, SO.sub.3H, NH.sub.2, halogen;
and R.sup.2, R.sup.4, if they are (C.sub.1-C.sub.12)-alkyl, (C.sub.3-C.sub.12)-cycloalkyl, (C.sub.3-C.sub.12)-heterocycloalkyl or (C.sub.6-C.sub.20)-aryl, may each independently be substituted by one or more substituents selected from (C.sub.1-C.sub.12)-alkyl, (C.sub.3-C.sub.12)-cycloalkyl, (C.sub.3-C.sub.12)-heterocycloalkyl, O(C.sub.1-C.sub.12)-alkyl, O(C.sub.1-C.sub.12)-alkyl-(C.sub.6-C.sub.20)-aryl, O(C.sub.3-C.sub.12)-cycloalkyl, S(C.sub.1-C.sub.12)-alkyl, S(C.sub.3-C.sub.12)-cycloalkyl, COO(C.sub.1-C.sub.12)-alkyl, COO(C.sub.3-C.sub.12)-cycloalkyl, CONH(C.sub.1-C.sub.12)-alkyl, CONH(C.sub.3-C.sub.12)-cycloalkyl, CO(C.sub.1-C.sub.12)-alkyl, CO(C.sub.3-C.sub.12)-cycloalkyl, N[(C.sub.1-C.sub.12)-alkyl].sub.2, (C.sub.6-C.sub.20)-aryl, (C.sub.6-C.sub.20)-aryl-(C.sub.1-C.sub.12)-alkyl, (C.sub.6-C.sub.20)-aryl-O(C.sub.1-C.sub.12)-alkyl, (C.sub.3-C.sub.20)-heteroaryl, (C.sub.3-C.sub.20)-heteroaryl-(C.sub.1-C.sub.12)-alkyl, (C.sub.3-C.sub.20)-heteroaryl-O(C.sub.1-C.sub.12)-alkyl, COOH, OH, SO.sub.3H, NH.sub.2, halogen.

The invention further relates to Pd complex mixtures comprising the diastereomers according to the invention, and to the use thereof in an alkoxycarbonylation process.

Compound of formula (I)

##STR00001##

where R.sup.2, R.sup.4 are each independently selected from (C.sub.1-C.sub.12)-alkyl, (C.sub.3-C.sub.12)-cycloalkyl, (C.sub.3-C.sub.12)-heterocycloalkyl, (C.sub.6-C.sub.20)-aryl; the R.sup.1, R.sup.3 radicals are each a (C.sub.3-C.sub.20)-heteroaryl radical; R.sup.1, R.sup.3 may each independently be substituted by one or more substituents selected from (C.sub.1-C.sub.12)-alkyl, (C.sub.3-C.sub.12)-cycloalkyl, (C.sub.3-C.sub.12)-heterocycloalkyl, O(C.sub.1-C.sub.12)-alkyl, O(C.sub.1-C.sub.12)-alkyl-(C.sub.6-C.sub.20)-aryl, O(C.sub.3-C.sub.12)-cycloalkyl, S(C.sub.1-C.sub.12)-alkyl, S(C.sub.3-C.sub.12)-cycloalkyl, COO(C.sub.1-C.sub.12)-alkyl, COO(C.sub.3-C.sub.12)-cycloalkyl, CONH(C.sub.1-C.sub.12)-alkyl, CONH(C.sub.3-C.sub.12)-cycloalkyl, CO(C.sub.1-C.sub.12)-alkyl, CO(C.sub.3-C.sub.12)-cycloalkyl, N[(C.sub.1-C.sub.12)-alkyl].sub.2, (C.sub.6-C.sub.20)-aryl, (C.sub.6-C.sub.20)-aryl-(C.sub.1-C.sub.12)-alkyl, (C.sub.6-C.sub.20)-aryl-O(C.sub.1-C.sub.12)-alkyl, (C.sub.3-C.sub.20)-heteroaryl, (C.sub.3-C.sub.20)-heteroaryl-(C.sub.1-C.sub.12)-alkyl, (C.sub.3-C.sub.20)-heteroaryl-O(C.sub.1-C.sub.12)-alkyl, COOH, OH, SO.sub.3H, NH.sub.2, halogen; R.sup.2, R.sup.4, if they are (C.sub.1-C.sub.12)-alkyl, (C.sub.3-C.sub.12)-cycloalkyl, (C.sub.3-C.sub.12)-heterocycloalkyl or (C.sub.6-C.sub.20)-aryl, may each independently be substituted by one or more substituents selected from (C.sub.1-C.sub.12)-alkyl, (C.sub.3-C.sub.12)-cycloalkyl, (C.sub.3-C.sub.12)-heterocycloalkyl, O(C.sub.1-C.sub.12)-alkyl, O(C.sub.1-C.sub.12)-alkyl-(C.sub.6-C.sub.20)-aryl, O(C.sub.3-C.sub.12)-cycloalkyl, S(C.sub.1-C.sub.12)-alkyl, S(C.sub.3-C.sub.12)-cycloalkyl, COO(C.sub.1-C.sub.12)-alkyl, COO(C.sub.3-C.sub.12)-cycloalkyl, CONH(C.sub.1-C.sub.12)-alkyl, CONH(C.sub.3-C.sub.12)-cycloalkyl, CO(C.sub.1-C.sub.12)-alkyl, CO(C.sub.3-C.sub.12)-cycloalkyl, N[(C.sub.1-C.sub.12)-alkyl].sub.2, (C.sub.6-C.sub.20)-aryl, (C.sub.6-C.sub.20)-aryl-(C.sub.1-C.sub.12)-alkyl, (C.sub.6-C.sub.20)-aryl-O(C.sub.1-C.sub.12)-alkyl, (C.sub.3-C.sub.20)-heteroaryl, (C.sub.3-C.sub.20)-heteroaryl-(C.sub.1-C.sub.12)-alkyl, (C.sub.3-C.sub.20)-heteroaryl-O(C.sub.1-C.sub.12)-alkyl, COOH, OH, SO.sub.3H, NH.sub.2, halogen.

The invention also relates to Pd complexes of the compound according to the invention, and to the use thereof in an alkoxycarbonylation process.

An apparatus for producing butadiene by way of oxidative dehydrogenation of a butane-rich feed stream includes: (a) a reactor adapted for receiving said butane-rich feed stream and converting butenes to butadiene by oxidative dehydrogenation, thereby providing a butadiene enriched product effluent stream which exits the reactor at an elevated temperature; (b) a superheater coupled to the reactor to receive the butadiene enriched product effluent stream from the reactor at elevated temperature as well as being configured to receive reactor feed, said superheater being adapted to transfer sensible heat from the butadiene enriched product effluent stream to reactor feed and provide superheated feed to the reactor and (c) a first feed vaporizer coupled to the superheater to receive the butadiene enriched product effluent stream as it exits the superheater and to transfer sensible heat from the butadiene enriched product effluent stream to reactor feed. Also provided are (d) a second feed vaporizer coupled to the reactor for providing vapor feed thereto; (e) a purification train for recovering butadiene from the butadiene enriched product effluent stream; and (f) a thermal oxidizer for recovering energy by way of oxidizing by-products from the purification train and providing energy for said second vaporizer.

Butadiene is formed by dehydrogenation of butenes which are mixed with steam and oxygen then converted to butadiene by oxidative dehydrogenation over a ferritic oxide catalyst, wherein the sensible heat in the oxidative dehydrogenation reaction product is utilized along with heat produced by thermal oxidation of low value volatile products formed to reduce energy requirements and CO.sub.2 emissions. Sensible heat is utilized at high temperature for purposes of superheating feed and at somewhat lower temperatures for purposes of vaporizing feed at sequential locations in the process.