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
  • C07C45/32—Preparation of compounds having >C = O groups bound only to carbon or hydrogen atoms; Preparation of chelates of such compounds by oxidation with molecular oxygen
  • C07C45/33—Preparation of compounds having >C = O groups bound only to carbon or hydrogen atoms; Preparation of chelates of such compounds by oxidation with molecular oxygen of CHx-moieties
  • C07C45/34—Preparation of compounds having >C = O groups bound only to carbon or hydrogen atoms; Preparation of chelates of such compounds by oxidation with molecular oxygen of CHx-moieties in unsaturated compounds
  • C07C45/36—Preparation of compounds having >C = O groups bound only to carbon or hydrogen atoms; Preparation of chelates of such compounds by oxidation with molecular oxygen of CHx-moieties in unsaturated compounds in compounds containing six-membered aromatic rings
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B65—CONVEYING; PACKING; STORING; HANDLING THIN OR FILAMENTARY MATERIAL
  • B65G—TRANSPORT OR STORAGE DEVICES, e.g. CONVEYORS FOR LOADING OR TIPPING, SHOP CONVEYOR SYSTEMS OR PNEUMATIC TUBE CONVEYORS
  • B65G47/00—Article or material-handling devices associated with conveyors; Methods employing such devices
  • B65G47/34—Devices for discharging articles or materials from conveyor 
  • B65G47/46—Devices for discharging articles or materials from conveyor  and distributing, e.g. automatically, to desired points
  • B65G47/48—Devices for discharging articles or materials from conveyor  and distributing, e.g. automatically, to desired points according to bodily destination marks on either articles or load-carriers
• • C—CHEMISTRY; METALLURGY
  • C07—ORGANIC CHEMISTRY
  • C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
  • C07C51/00—Preparation of carboxylic acids or their salts, halides or anhydrides
  • C07C51/16—Preparation of carboxylic acids or their salts, halides or anhydrides by oxidation
  • C07C51/21—Preparation of carboxylic acids or their salts, halides or anhydrides by oxidation with molecular oxygen
  • C07C51/255—Preparation of carboxylic acids or their salts, halides or anhydrides by oxidation with molecular oxygen of compounds containing six-membered aromatic rings without ring-splitting
  • C07C51/265—Preparation of carboxylic acids or their salts, halides or anhydrides by oxidation with molecular oxygen of compounds containing six-membered aromatic rings without ring-splitting having alkyl side chains which are oxidised to carboxyl groups

Definitions

• This invention relates to the manufacture of aromatic carboxylic acids. It is more particularly concerned with a process for oxidizing a methyl-substituted aromatic compound to the corresponding carboxylic acid or acids.
• methyl-substituted aromatic compounds can be oxidized in the liquid phase at atmospheric pressure. It has been discovered that certain branched-chain alkyl-substituted aromatic hydrocarbons act as promoters for the oxidation of methylarom-atic compounds to aromatic carboxylic acids at atmospheric pressure. Accordingly, it is a broad object of this invention to provide a process for producing aromatic carboxylic acids. Another object is to provide a method for oxidizing methylaromatic compounds to carboxylic acids. A specific object is to provide a process for oxidizing methylaromatic compounds to aromatic carboxylic acids at atmospheric pressure. Another specific object is to provide a process for oxidizing methylaromatic compounds to aromatic carboxylic acids that is promoted by certain bran-ched chain alkyl-substituted aromatic hydrocarbons.
• the present invention provides a method for producing aromatic carboxylic acids that comprises establishing a reaction mixture of a methylaromatic compound and an alkylaromatic hydrocarbon promoter, wherein the alkyl group has a secondary carbon atom directly attached to the aromatic nucleus, and the Weight ratio of said methylaromatic compound to said alkylaromatic promoter being between about 0.121 and about :1, maintaining said reaction mixture at a temperature varying between about 50 C.
• Theprocess of this invention is applicable to the oxidation of methyl-substituted aromatic hydrocarbons to.
• oxidation contemplated herein include the oxidation of toluene to hen-- zoic acid, the oxidation of xylene to toluic acid, and the oxidation of methylnaphthalene to naphthoic acid. It
• methyl-substituted aromatic carboxylic acids can be directly oxidized to polycarboxylic aromatic acids, without resort to converting the methylaromatic carboxylic acid to the ester.
• it is contemplated to oxidize p-toluic acid to terephthalic acid, without first converting to the methyl toluate ester.
• non-limiting examples of the methyl-substituted aromatic compounds oxidizable in the process of this invention include, toluene, o-xylene, m-xy-lene, pxylene, hemimellitene, psuedocumene, mesitylene, a-rnethylnaphthalene, ,6 methylnaphthalene, dimethylnaphthalene, o-toluic acid, m-toluic acid, p-toluic acid, hemimellitic acid, xylic acid, mesitylenic acid, methylpyridine, pch lorotoluene, tolunitrile.
• methylaromatic compounds which are diflicult to oxidize at atmospheric pressure, are readily oxidized when a promoter is used.
• the promoters contemplated herein are alkylaromatic hydrocarbons in which the alkyl group has a secondary carbon atom directly attached to the aromatic nucleus. These compounds have a structure:
• R and Rf are alkyl groups containing 1-3 carbon atoms. These compounds have one hydrogen atom in a position alpha to the aromatic nucleus.
• promoters include cumene, isobutylbenzene, isoamylbenzene, 3-phenylpentane, 3-phenylhexane, and 4- phenylheptane. Cumene is particularly preferred from the standpoint of its ready availability and effectiveness.
• the amount of promoter used, in proportion to the amount of methylaromatic charge, can vary somewhat. Generally, the weight ratio of methylaromatic compound to promoter will vary between about 10:1 and about 0.1 1. Preferably, it will be between about 4:1 and about 0.2:1.
• the oxidation reaction is carried out in the liquid phase by contacting the methylaromatic-promoter mixture with oxygen in the presence of a catalyst, at temperatures which permit operation at atmospheric pressure.
• the oxidation reaction (as previously had been proposed) requires elevated temperatures which are considerably higher than the boiling point of the methylaromatic compound. Accordingly, superatmospheric pressures have been required to maintain liquid phase.
• the present process operates at temperatures ranging from about 50 C. up to the boiling point of the methylaromatic compound reactant.
• the highest reaction temperature will be within about 15 C. of the boiling point of the methylaromatic compound reactant.
• Oxygen is supplied to the process as relatively pure oxygen or in the form of a molecular oxygen-containing gas, such as air.
• the amount of oxygen used (measured in terms of molecular oxygen, in the case of oxygencontaining gas) will vary between about 0.1 cubic foot hour and about 5 hours.
• alkylaromatic hydrocarbon promoter such as cumene
• the promotion effect has been noted even in the absence of an oxidation catalyst.
• the effect is less pronounced, i.e. relatively lower conversions to carboxylic acids are noted for the same reaction conditions.
• the alkylaromatic hydrocarbon promoter will effect improved yields in any liquid phase, catalytic process for oxidizing methylaromatic hydrocarbons to aromatic carboxylic acids.
• the promotional eifect of this invention is not dependent upon the particular oxidation catalyst selected and will be observed with any of the oxidation catalysts known to the art.
• oxidation catalysts used in the art have been extensively investigated and found elfective in this invention.
• One preferred type is a heavy metal phthalocyanine or porphorazine, such as, for example, iron phthalocyanine.
• Another type of catalyst includes metal salts of organic carboxylic acids, such as, cobalt naphthenate, cobalt permanganate, cerium chloride, copper phosphate, vanadium chloride, and manganese acetate.
• the more eifective catalysts of this type are those wherein the metal is in its lower valence state, e.g. cobaltous naphthenate or acetate.
• the oxidation catalysts commonly used include the solid polyvalent metals having an atomic weight between about 50 and 200.
• the metals, themselves, may be used in the finely divided metallic state, or as oxides or as compounds of the types already referred to. Mixtures of two or more oxidation catalysts may be utilized if desirable.
• part of the alkylaromatic promoter will be oxidized.
• some will be converted to acetophenone, a material useful as a perfume ingredient and as lacquer thinner.
• aromatic carboxylic acids can be removed in any of the various ways for separating organic acids from hydrocarbons.
• the carboxylic acid can be neutralized by adding an aqueous solution of alkali, such as aqueous sodium or potassium hydroxide, to the reaction product to obtain an aqueous solution of the salt of the aromatic carboxylic acid.
• The'aqueous solution is separated from the organic material (unreacted reactant, ketones, etc.) and then acidified to release the aromatic 4 amples, or by the operations or manipulations involved. .As will be apparent to those skilled in the art, other reactants and conditions, as set forth herein, can be used to practice this invention.
• the caustic-insoluble oil fraction was analyzed by vapor phase chromatographic analysis and showed 8% acetophenone, i.e. conversion of about 40% of the cumene to acetophenone. Unreacted toluene and cumene are recoverable by distillation for recycle to the process.
• Example 2 Another run similar to that of Example 1 was made, except that no cumene promoter was used. After 3% hours operation at 110 C. using an oxygen flow rate of 0.5-0.6 cubic foot per hour, there was produced no benzoic acid.
• Example 3 Two runs were made, as described in Example 1, using air as the source of oxygen.
• the flow rates were 0.7-0.8 cubic foot of air per hour, equivalent to an oxygen flow rate of about 0.14-0.16 cubic foot per hour.
• the ratio of toluene to cumene was 4:1 and in the other, 121.
• Pertinent data on these run and on the runs of Examples 1 and 2 are summarized in Table I.
• the run is summarized xamp e in Table 11.
• a charge of 50 grams m-xylene, 50 grams Example 6 cumene, and 0.5 gram iron phthalocyanine was oxidized for 3.2 hours at 135 C., using an oxygen rate of 0.3-0.4 A fun slmllar to that Of Example 5 was made except cubic foot per hour.
• a crude acid product was obtained t at 110 6111118116 Was used: The Charge W 75 grams (14 grams) which, when recrystallized from water, pand 0375 gram lfOIl phthalocyanlh? Oxygen melted at l079 C. Reported melting point of metawas bubbled through the charge at 135 C.
• Example 10 arge of hgh 811115 fY 7 g t ii fi gg g A run was made as described in Example 9, except that gram Iron P t a Ocyanme was e at no cumene promoter was used.
• the Product was 40 for 24 hours at 135 C., using an oxygen rate of 0.3 cubic cooled and extracted with 200 ml. of 10% potassium foot per hour. No measurable yield of oxidation product hydroxide.
• Nil Nil 1 Fe PTO is iron phthalocyanine.
• the cooled oxidation product was extracted with three 100 ml. portions of 10% sodium hydroxide solution, leaving 90 grams of caustic-insoluble oil. Neutralization of the caustic extract with 10% hydrochloric acid produced grams of crude acid, which was crystallized from water to yield while crystals having a melting range of 157160 C. The reported melting point of mesitylenic acid is 166 C. The acid number of the acid was 368 (theoryfor mesitylenic acid, 374).
• Example 12 A solution containing 20 grams of p-toluic acid, 80 grams of cumene and 0.5 gram of iron phthalocyanine were heated at 135 C. while oxygen was passed through the solution at a rate of 0.4 cubic foot per hour for 3 hours. The solution was filtered hot and 2.35 grams of solid acid were separated in this fashion (terephthalic acid is extremely insoluble in most organic solvents while p-toluic acid is soluble in hot organic solvents). The solid wasdigested with two 400 ml. portions of hot water and the insoluble solid separated by filtration and dried in a drying pistol, weight 2.32 grams. This solid did not melt when heated to 220 C. and gave an acid number with two breaks (indicative of two carboxyl groups). Acid numbers found:' 337, 453; theoretical for terephthalic acid: 338, 674. (Solubility problems render it ditficult to obtain a satisfactory second break in the acid number determination for pure terephthalic acid.)
• Example- 13 Sixty grams of p-xylene and 60 grams of cumene were oxidized (note: no oxidation catalyst was used) at 135 C. for 7 hours using oxygen at a flow rate of 0.3 cubic foot per hour. The crude p-toluic acid obtained weighed 6 grams and was similar to that prepared in Example 5. 1
• Recrystallization gave a solidp-toluic acid of melting point 1748 C. which did not depress the melting point of known p-toluic acid when added thereto.
• a method for producing aromatic carboxylic acids that consists essentially of establishing a reaction mixture of a rnethylaromatic hydrocarbon and an alkylaromatic hydrocarbon promoter having the structure:
• R and R are alkyl groups having 1-3 atoms, and the weight ratio of said methylaromatic hydrocarbon and said alkylaromatic promoter being between about 0.1:1 and about 10:1; maintaining said reaction mixture at a temperature varying between about 50 C. and about 135 C. and under atmospheric pressure; and contacting said reaction mixture in the liquid phase with a molecular oxygen-containing gas at a flow rate, measured in terms of oxygen, varying between about 0.1 cubic foot per hour and about 4 cubic feet per hour per 100 g. of said reaction mixture, and for a period of time varying between about 0.5 hour and about 10 hours.
• a method for producing benzoic acid that consists essentially of establishing a reaction mixture of toluene wherein R and R are alkyl groups having 1-3 C atoms, and the weight ratio of said toluene to said alkylaromatic promoter being between about 0.2:1 and about 4: 1; maintaining said reaction mixture at a temperature varying between about 50 C. and about 110 C.; and under atmospheric pressure and contacting said reaction mixture with a molecular oxygen-containing gas at a flow rate, measured in terms of oxygen, varying between about 0.2 cubic foot per hour and about 0.5 cubic foot per hour per g. of said reaction mixture, in the presence of cobalt naphthenate catalyst, and for a period of time varying between about one hour and about 5 hours.
• a method for producing benzoic acid that consists essentially of establishing a reaction mixture of toluene and cumene promoter, the weight ratio of said toluene to said cumene being between about 0.221 and about 4: l; maintaining said reaction mixture at a temperature of about C. and under atmospheric pressure; contacting said reaction mixture with oxygen at a fiow rate'varying between about 0.2 cubic foot per hour and about 0.5 cubic foot per hour per 100 g. of said reaction mixture, in the presence of cobalt naphthenate catalyst, and for a period of time varying between about one hour and about 5 hours; and recovering benzoic acid from the reaction mixture.
• a method for producing benzoic acid that consists essentially of establishing a reaction mixture of toluene and cumene promoter, the weight ratio of said toluene to said cumene being between about 0.221 and about 4: 1; maintaining said reaction mixture at a temperature of about 110 C. and under atmospheric pressure; contacting said reaction mixture with air at a flow rate, measured in terms of oxygen, varying between about 0.2 cubic foot per hour and about 0.5 cubic foot per hour per 100 g. of said reaction mixture, in the presence of cobalt naphthenate catalyst, and for a period of time varying between about one hour and about 5 hours; and recovering benzoic acid from the reaction mixture.
• a method for producing toluic acids that consists essentially of establishing a reaction mixture of xylene and cumene promoter, the weight ratio of said xylene to said cumene being between about 0.211 and about 4:1; maintaining said reaction mixture at a temperature varying between about 50 C. and about C. and under atmospheric pressure; and contacting said reaction mixture with oxygen at a flow rate varying between about 0.2 cubic foot per hour and about 0.5 cubic foot per hour per 100 g. of said reaction mixture, and for a period of time varying between about 0.5 hour and about 5 hours.
• a method for producing paratoluic acid that consists essentially of establishing a reaction mixture of pxylene and cumene promoter, the weight ratio of said p-xylene to said cumene being between about 0.2:1 and about 4: 1; maintaining said reaction mixture at a temperature of about 135 C. and under atmospheric pressure; contacting said reaction mixture with oxygen at a flow rate varying between about 0.2 cubic foot per hour and about 0.5 cubic foot per hour per 100 g. of said reaction mixture in the presence of iron phthalocyanine catalyst, and for a period of time varying between about one hour and about 5 hours; and recovering paratoluic acid from the reaction mixture.
• a method for producing orthotoluic acid that consists essentially of establishing a reaction mixture of oxylene and cumene promoter, the Weight ratio of said 0- xylene to said cumene being between about 0.2:1 and about 4:1; maintaining said reaction mixture at a temperature of about 135 C. and under atmospheric pressure; contacting said reaction mixture with oxygen at a flow rate varying between about 0.2 cubic foot per hour and about 0.5 cubic foot per hour per 100 g. of said reaction mixture, in the presence of iron phthalocyanine catalyst, and for a period of time varying etween about one hour and about 5 hours; and recovering orthotoluic acid from the reaction mixture.
• a method for producing metatoluic acid that consists essentially of establishing a reaction mixture of mxylene and cumene promoter the weight ratio of said mxylene to said cumene being between about 02:1 and about 4:1; maintaining said reaction mixture at a temperature of about 135 C. and under atmospheric pressure; contacting said reaction mixture with oxygen at a flow rate varying between about 0.2 cubic foot per hour and about 0.5 cubic foot per hour per 100 g. of said reaction mixture, in the presence of iron phthalocyanine catalyst, and for a period of time varying between about one hour and about 5 hours; and recovering metatoluic acid from the reaction mixture.
• a method for producing mesitylenicacid that consists essentially of establishing a reaction mixture of rnesitylene and cumene promoter, the weight ratio of said mesitylene to said cumene being between about 0.211 and about 4:1; maintaining said reaction mixture at a temperature of about 135 C. and under atmospheric pressure; contacting said reaction mixture with oxygen at a flow rate varying between about 0.2 cubic foot per hour and about 0.5 cubic foot per hour per 100 g. of said reaction mixture, in the presence of iron phthalocyanine catalyst, and for a period of time varying between about one hour and about 5 hours; and recovering mesitylenic acid from the reaction mixture.
• a method for producing terephthalic acid that consists essentially of establishing a reaction mixture of p- References Cited by the Examiner UNITED STATES PATENTS 2,245,528 6/1941 Loder 260-524 2,833,816 5/1958 Safier et a1 260-524 3,139,452 6/ 1964 Hay 260524 FOREIGN PATENTS 681,455 10/1952 Great Britain.

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  • BE BE602086D patent/BE602086A/xx unknown
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• 1961
  • 1961-03-30 FR FR857289A patent/FR1299531A/fr not_active Expired
  • 1961-04-04 GB GB12026/61A patent/GB966986A/en not_active Expired
• 1963
  • 1963-08-26 US US304614A patent/US3256324A/en not_active Expired - Lifetime

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