Classifications

• • C—CHEMISTRY; METALLURGY
  • C07—ORGANIC CHEMISTRY
  • C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
  • C07C45/00—Preparation of compounds having >C = O groups bound only to carbon or hydrogen atoms; Preparation of chelates of such compounds
  • C07C45/27—Preparation of compounds having >C = O groups bound only to carbon or hydrogen atoms; Preparation of chelates of such compounds by oxidation
  • C07C45/30—Preparation of compounds having >C = O groups bound only to carbon or hydrogen atoms; Preparation of chelates of such compounds by oxidation with halogen containing compounds, e.g. hypohalogenation
• • C—CHEMISTRY; METALLURGY
  • C07—ORGANIC CHEMISTRY
  • C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
  • C07C45/00—Preparation of compounds having >C = O groups bound only to carbon or hydrogen atoms; Preparation of chelates of such compounds
  • C07C45/27—Preparation of compounds having >C = O groups bound only to carbon or hydrogen atoms; Preparation of chelates of such compounds by oxidation
  • C07C45/28—Preparation of compounds having >C = O groups bound only to carbon or hydrogen atoms; Preparation of chelates of such compounds by oxidation of CHx-moieties

Definitions

• Carbonyl compounds are produced by the oxidative cleavage of an unsaturated olifinic hydrocarbon by a process which comprises contacting the hydrocarbon with a neutral to acidic aqueous solution of a catalyst comprising ruthenium together with a cerium salt having an oxidation potential greater than 1.5 volts.
• the cerium salt oxidizing agent is regenerated electrochemically.
• This invention relates to improvements in the process for the production of carbonyl compounds including carboxylic acids, aldehydes and ketones, by the oxidation of olefinic hydrocarbons. More particularly, this invention relates to a process for the oxidative cleavage of olefinic hydrocarbons to aldehydes in the presence of a ruthenium catalyst and an oxidizing agent, the oxidizing agent being regenerated by electrochemical oxidation.
• carbonyl compounds such as carboxylic acids, ketones and aldehydes can be obtained in good yield in a continuous manner, if desired, by contacting olefinic hydrocarbons with a catalytic amount of ruthenium in the presence of at least one oxidizing agent having a formal oxidation potential greater than 1.5 volts.
• the oxidizing agents useful in the process of this invention include compounds of metals which appear in various oxidation states and which have formal oxidation potentials greater than 1.5 volts with reference to the standard hydrogen electrode. Compounds with potentials above about 1.5 volts are capable of oxidizing the lower states of ruthenium to ruthenium tetroxide [Ru(VIII)].
• Some of the oxidizing agents which have been found applicable in this invention include compounds such as cerium perchlorate, cerium nitrate, cerium methanesulfonate, nitric acid and hypochlorous acid.
• the ruthenium catalyst forms an addition compound or complex with the olefinic hydrocarbon, although the exact mechanism which cleaves olefins to aldehyde is speculative.
• the stoichiometric reaction requires a four electron change.
• olefinically unsaturated hydrocarbon which is free from steric hinderance
• Compounds which are most useful in the process according to this invention are olefins such as butene, propene, hexene, heptene, octene cyclohexene, styrene and their substituted homologs such as Z-methyl propene.
• oxidizing agent For a continuous process it is necessary to regenerate the oxidizing agent, which in turn facilitates the reformation of the higher oxidation state of the active ruthenium catalyst component necessary to carrying out the reaction.
• Certain of the oxidizing agents applicable to the process of this invention can be regenerated by electrochemical oxidation.
• solutions of cerium (IV) are conveniently made by electrolytic oxidation of cerium (III). In this process a diaphragm electrolytic cell need not be used.
• Electrodes which may be used for the electrochemical process include inert materials such as platinum, graphite, lead, tantalum and others. Cerium (III) is oxidized at the anode to cerium (IV) in either a divided or undivided cell while hydrogen gas is produce in an undivided cell and caustic in a divided cell at the cathode.
• the electrochemical oxidation of Ce(III) to Ce(IV) may be carried out at temperatures ranging from about 10 to C. and preferably from about 25 to 50 C. Anode current densities of 1040 milliamps per sq. cm. with cell terminal voltages of 3.2 to 3.5 volts are sufficient for high conversion rates.
• the process according to this invention is preferably carried out in an aqueous system, however, the reaction media may be diluted with substances which act as coupling agents such as t-butyl alcohol or acetic acid which are inert under the reaction conditions. It is necessary that the reaction be carried out in a neutral to acidic medium.
• the reaction is substantially pH independent from a pH of 1 to 5. When an undivided electrolytic cell is used, acid is consumed during the reaction. This necessitates the addition of acid during the course of the reac tion to assure adequate pH control.
• the process of this invention can be carried out at temperatures ranging from about 0 to 200 C. and preferably from 25 to 50 C. An increase in temperature results in a corresponding increase in reaction rate. At higher temperatures side reactions occur which lower the yields of desired products.
• the process of this invention can be carried out at atmospheric pressure, at subatmospheric pressure or at superatmospheric pressure, e.g. pressures ranging from 0 to 1500 p.s.i.
• pressures greater than atmospheric may be used to promote the solubility of the olefin in the aqueous reaction medium.
• the molar ratio of ruthenium to the oxidizing agent employed is not particularly critical to this process.
• the amount of ruthenium necessary to catalyze the reaction is very small, ranging from about 1 1O Molar to 1 1O- Molar.
• the oxidizing agent need only be present in amounts sufficient to oxidize ruthenium to its active catalytic state, e.g. a ruthenium/oxidizing agent molar ratio of at least 1:1.
• An excess of olefin is normally used in the process of this invention to minimize secondary oxidation.
• the secondary oxidation which occurs in this instance is the oxidation of the aldehyde, formed as a result of the oxidation of the olefin, to the corresponding acid.
• a stirred two phase system may be used.
• a liquid olefin such as octene-l, which is oxidized to heptaldehyde in the presence of ruthenium [Ru(VII-I)]
• the heptaldehyde preferably concentrates in the olefin phase rather than the aqueous phase, thus minimizing secondary oxidation.
• the aldehyde concentration is minimized in the aqueous phase, it will be relatively free from further oxidation.
• the process may be carried out by a batchwise or continuous process, although a continuous process is preferred.
• a continuous process the following description is given.
• An oxidizing agent is fed to a reaction zone containing the desired olefinic hydrocarbon and an aqueous solution of ruthenium catalyst.
• the organic phase is removed from the reaction zone and continuously fed to a distillation column where the olefinic hydrocarbon is separated from the desired aldehyde product and recycled to the reaction zone.
• the aqueous spent oxidizing agent is recycled to the electrolytic cell for regeneration. Regeneration of the oxidizing agent may also be carried out in the reaction zone by electrochemical oxidation.
• octene-l may be oxidized to give heptaldehyde and formaldehyde, heptaldehyde being a useful intermediate in the production of adipaldehyde and adipic acid, a useful nylon raw material intermediate.
• EXAMPLE I A stirred electrolytic cell having an anode made of platinum gauze and a cathode of platinum wire was used as the reactor. A solution of 0.2 F cerium (III) in 1 N perchloric acid was added to the reactor-electrolytic cell. Three millifaradays of electricity were passed through the electrolyte. The current was 100 milliamperes and the cell voltage was about 2 volts. The current efficiency to ceric ion was about 90%. Twenty milliliters of octene-l and sufiicient ruthenium as ruthenium chloride were added to the reactor electrolytic cell. The concentration of ruthenium was 1 l0 F. The total aqueous phase was 80 milliliters.
• the reaction was allowed to proceed until the solution was colorless indicating the absence of cerium (IV), which has a yellow color.
• the products obtained were analyzed and the following results obtained: 3.6 oxidation equivalents heptaldehyde, 6.27 oxidation equivalents formic acid, 0.48 equivalents formaldehyde.
• the efiiciency to heptaldehyde based on Ce(IV) was 36%
• the efiiciency to heptaldehyde based on octene-l was approximately 95%.
• EXAMPLE II was carried out in nitric acid.
• methanesulfonic acid was used.
• acetic acid was added to the reaction media as a coupling agent or solubilizer.
• the higher proportion of heptanoic acid and formic acid indicates that secondary oxidation of the aldehyde to the corresponding acid occurred as the result of the, influence of the acetic acid coupling agent.
• a higher concentration of ruthenium was used.
• EXAMPLE III Employing the reactor-cell as described in Example 1 runs were made in which ceric was continuously reacted and regenerated electrolytically as shown by Table II. The runs were made by passing current through the well mixed octene-aqueous two phase mixture. The current density was adjusted to generate ceric (yellow color) at a rate approximating the organic oxidation rate. An attempt was made to keep the solution light yellow. After passing the desired quantity of electricity, the excess ceric was allowed to react to completion as indicated by decolorization. The products were removed and analyzed.
• Run 1 was made with unpurified octene. Runs 2 and 3 gave very high current efiiciencies. In Run 4 the ruthenium concentration was reduced to 5 10 F and the temperature increased to 50 C. The conversion was relatively high and the current eificiency was 57%.
• TABLE II.GERIC OXIDATION OF OCTENE-l IN A TWO- PHASE SYSTEM CONCURRENT ELECTROLYTIC GEN- ERATION OF CERIO [Pt screen anode:100 sq. cm.; Pt wire cathode:1 sq. cm.; stgrretl diaphragmless cell; 80 ml. ag. phase; 20 ml.
• Heptene-3 was found to yield propionic acid and butyric acid instead of propionaldehyde and butyraldehyde because of the preference of the aldehydes for the aqueous phase in which secondary oxidation occurred.
• Cyclohexene was oxidized to a mixture of adipaldehyde and adipic acid.
• Methyl oleate was oxidized to give the following products according to the equation:
• Nonanol was obtained along with some nonanoic acid.
• Alpha-pinene was oxidized to a mixture of products including pinonic aldehyde.
• EXAMPLE V A reactor-column arrangement for the continuous production of heptaldehyde from octene-l was set up using the electrolytic cell-reactor arrangement as described in Example I. The conditions under which the reaction took place are shown by Table III. Heptaldehyde boils at 155 C. while octene-l boils at 121.3 C. Heptaldehyde produced from the reaction with octene-l was introduced at an intermediate point on a distillation column.
• the reboiler of the distillation column was kept at a tem perature sufiicient to remove unreacted octene-l overhead for recycle back to the reactor zone while the heptaldehyde was taken off at the bottom of the column.
• Heptaldehyde 1. 44 4. 72 3.0 Heptanoic acid 0 0 Current efiiciency to heptaldehyde,
• EXAMPLE VI Using the diaphragmless electrolytic cell and reaction conditions as described in Example I, octene-l was oxidized to heptaldehyde using manganese as the oxidizing agent for ruthenium instead of cerium. The manganese was electrolytically regenerated.
• EXAMPLE VIII A continuous run was made as described in Example V using n-hexane saturated with butene-Z as the liquid oil phase instead of heptaldehyde. From the reactor the liquid oil phase was passed to the middle of the distillation column and butene, acetaldehyde and some hexane removed overhead. Stripped hexane, from the base of the column, was recycled to the reaction zone by way of a bubbler which saturated the hexane with butene-Z. The conditions and efiiciencies are given below.
• a continuous process for the production of a carbonyl compound selected from the group consisting of aldehydes, carboxylic acids, and ketones by oxidative cleavage of an unsaturated olefinic hydrocarbon which comprises contacting said olefinic hydrocarbon in the presence of a neutral to acidic aqueous catalyst solution comprising a ruthenium catalyst and a cerium salt whose oxidation potential is greater than 1.5 volts at a temperature of 0 to 200 C., removing the reaction products from the reaction zone as they are formed, and regenerating the cerium salt by electrochemical oxidation.

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• Chemical & Material Sciences (AREA)
• Organic Chemistry (AREA)
• Electrolytic Production Of Non-Metals, Compounds, Apparatuses Therefor (AREA)
• Organic Low-Molecular-Weight Compounds And Preparation Thereof (AREA)

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Citations (8)

• 1966
  • 1966-01-03 US US517959A patent/US3459644A/en not_active Expired - Lifetime
  • 1966-12-29 DE DE19661568363 patent/DE1568363A1/de active Pending
• 1967
  • 1967-01-03 NL NL6700029A patent/NL6700029A/xx unknown
  • 1967-01-03 BE BE692143D patent/BE692143A/xx unknown
  • 1967-01-03 FR FR89775A patent/FR1507137A/fr not_active Expired

Patent Citations (8)

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