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Home , Anisole, Dimethyl sulfate

Nov. 14, 1950 W. D., SMUTZ 2,529,887 PROCESS FOR THE PREPARATION OF ANSOLE Filed May 19, 1949

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CONDENSER

SODUM HYDROXDE

HEAT

EXCHANGER

INVENTOR. WALTER D. SMUTZ 6-4 7%. 6226. AGENT

Patented Nov. 14, 1950 2,529,887 UNITED STATES PATENT OFFICE 2,529,887 PROCESS FOR THE PRE PARATION OF ANSOLE Walter D. Smutz, Warrensville Heights, Ohio, as signor to E. E. du Pont de Nemours & Company, Wilmington, Del, a corporation of Delaware Application May 19, 1949, Serial No. 94,226 Clains, (C. 260-612) 2 This invention relates to the manufacture of portion of the still which contains a large body . More particularly it relates to continu Of not a queous Sodium phenate. ous processes in which a methylating agent for The base of the still is preferably conically phenol is added continuously to a stream of refor Shaped to facilitate the collection and withdrawal tified aqueous sodium phenate maintained in froin the Still of Crystalline Sodium Which turbulent flow. The stream is heated to form is a by-product of the ainiSole process. The Sodi anisole therein. The anisole is separated and un un. Sulfate is withdra Win thru line 9 according to reacted aqueous sodium phenate is refortified by the enbodiment of the invention illustrated in adding phenol and an alkaline Sodium compound. the dra Wing. A stream of the refortified aqueous sodium phe 10 Hot a queous Sodiun phenate is withdrawn nate is then recycled for admixture with the from Still thru line 5. This hot aqueous Sodium Aethylating agent. phenate is refortified by the addition of Sodium This application is a continuation-in-part of hydroxide thru line and phenol thru line . my copending applications Serial No. 724,718, line Sodium hydroxide and phenol are added in filed January 27, 1947, now U. S. Patent 2,490,842 5 Substantially Stoichiometric proportions and in issued December 13, 1949, and Serial No. 15,760 aimou Eat Sufficient to naaintain the sodium phenate filed March 19, 1948, now abandoned. strength in the refortified Solution at a prede It is an object of this invention to provide proc termined value. After an intimate mixing of esses which are practical and economical for the newly added Sodium hydroxide and phenol, the commercial production of anisole in high 2) as in pipe line mixer 6, to give the refortified hot yield using as reactants phenol, a methylating aqueous Sodium phenate, is agent for phenol, and an alkaline Sodium COn added to a turbulent stream of the refortified pound selected from the class consisting of Sodium liquid ahead of the inlet of a pump 7. hydroxide and a sodium carbonate. Other ob The pump 7 following the inlet point of the jects and advantages of the invention Will become 25 dimethyl Sulfate is preferably a centrifugal pump apparent from the following description and ac So aS to effect a rapid allinoSt instantaneous mix coinpanying drawing. ing of the dimethyl Sulfate with the aqueous sodi Processes of the invention are illustrated in the in phenate So that local excesses of the dimethyl drawing on which there is shown in Senidia Sulfate are avoided. grammatical form an apparatus adapted for use 30 A homogeneous liquid maSS flows from pump 7 in the practice of a preferred embodiment of the into heat eXchanger 3. In the heat exchanger, present invention. In the processes illustrated Sufficient heat is introduced into the reacting mass by the drawing, dinnethyl Sulfate is used as the to effect substantial completion of the anisole methylating agent and the alkaline SOdium Com forming reaction and to Steain distill anisole pound employed is sodium hydroxide. 3 5 present in the maSS. The heated reacting mass Having reference to the drawing, there Will be then leaves the heat eXchanger thru pipe 2 and seen as a central unit a still . The still has an is expanded into Still at point 4 as previously inet pipe 2 leading from the heat eXchanger 3 described. into the upper part of the still at point 4 and an The items in the drawing which have not yet outlet pipe 5 leading thru a pipe line mixer 6 and () been referred to relate to the recovery of the a punp to the heat eXchanger 3, thus pernit product anisole and the by-product sodium sul ting a cyclic flow of materials. The still also has fate and they will be considered in more detail other outlet and inlet lines as will be more fully later. described later. Turning now to a consideration in greater de According to the processes of the invention ill 45 tail of the operating conditions of applicant's lustrated in the drawing, an inlet pipe 2 conveys preferred proceSS illustrated by the drawing, it a heated aqueous reacting maSS containing ani is to be noted at the OutSet that still contains sole, sodium phenate, and Sodium Sulfate from a volume of a dueois Sodium phenate which is the heat, exchanger 3 to the upper part of the large compared with the volume of materials stil. The upper part of the still is preferably 50 added to the proceSS pei minute. For example, cylindrical and the heated reacting maSS is ex according to a preferred embodiment, the process panded into this upper part tangentially at point is operated so that there is maintained in the still 5, thus imparting a rotatory motion to the heated from 500 to 1500 gallions of aqueous. Sodium aSS. phenate for each gallon of materials added to the Upon expanding the heated mass into the still 55 process per minute. Additionally the process is at point 4, a mixture of anisole and water is operated so that the amount of aqueous sodium vaporized or “flashed off' from the maSS and phenate withdrawn for recycle is only a fraction leaves the still thru line 8. The unvaporized re of the volume contained in the still. For example, mainder of the mass which consists predoni the volume of aqueous sodiun phenate in the Still nantly of aqueous sodium phenate and a Small 60 is preferably from 2 to 6 gallons for each gallon of amount of sodium sulfate drops into the lower the solution withdrawn per minute for recycle, 2,529,887 3 4. The retention of a large body of aqueous what with the strength of the sodium phenate so sodium phenate in the still serves a multiple func lution. Preferably the rate of addition is from tion. The liquid body in the still acts as a reser 0.5 thru 1.0 part by weight of dimethyl sulfate voir for the reactant, sodium phenate, as a source per 1000 parts by weight of the refortified aqueous of constant supply of a uniform liquid to serve as s Sodium phenate solution. a diluent in the reaction process and in general According to the invention, the rate of addi as a “flywheel' for the process; that is, the body tion of dimethyl sulfate is also coordinated with of liquid in the still has a function which is anal the additions of sodium hydroxide and phenol ogous to a flywheel in a machine in that the so that these three reactants are introduced into body of liquid acts to moderate and minimize, be ) the system in Substantially the Stoichiometric cause of its mass, fiuctuations and variations in proportions required for the formation of anisole. the addition of reactants, temperatures and usual In other words, Substantially one-half mol of process variables, thus stabilizing the process. dimethyl Sulfate is added for each mol of phenol As mentioned previously, sodium hydroxide and added to the system. phenol are introduced thru pipes 0 and , re The homogeneous liquid leaving pump paSSes spectively, into hot aqueous sodium phenate with into heat exchanger 3. In the heat exchanger drawn from still thru line 5. The Sodium hy the reacting mass is heated to a temperature droxide and the phenol are added in Substantially - above 106° C. and preferably to a temperature of st oichiometric proportions for the formation of 108° C. thru 1.15° C. The reacting mass in the sodium phenate to form what has been termed 20 heat exchanger is maintained under pressure, the refortified aqueous sodium phenate. It is preferably a pressure of 15 thru 45 pounds per Sq. preferred that the aqueous Sodium phenate So inch gauge. Sufficient heat is introduced into lution in the reaction cycle be maintained sub the reacting mass to steam distill the anisole pres stantially neutral, that is, that where there be no ent in the maSS. appreciable excess of either sodium hydroxide or 2 5 As pointed out previously, the heated reacting phenol in the liquid maSS. To maintain this mass from the heat exchanger is passed into the neutral condition, it may be necessary Occasion vapor space of still . Preferably the heated ally to add more than the stoichiometric amount mass is expanded tangentially into the Vapor of sodium hydroxide but ordinarily once the proc space of the still at point 4, thus imparting a ess has been operated for awhile and Stabilized at 30 rotatory motion to the heated mass as it is in uniform conditions, it is not necessary to vary the troduced into the distillation Zone. sodium hydroxide and phenol from approximately Upon expansion into the vapor Space of the stoichiometric proportions. distillation Zone, a mixture of anisole and Water The refortified aqueous solution of sodium flashes off from the heated mass. The ratio of phenate should contain at least 28 per cent by ) weight of sodium phenate and more preferably it Water to anisole in the vapors which flash off contains from 35 thru 45 per cent sodium phenate. will vary somewhat with the operating conditions Accordingly the addition of sodium hydroxide but will generally be in the order of about 3 parts and phenol to the recycle aqueous Sodium phenate by weight of water for each part by weight of Withdrawn from still to effect the refortifica anisole. The vaporized anisole-water mixture is tion is controlled to maintain uniformly a pre withdrawn thru pipe 8 and the unvaporized por determined sodium phenate concentration con tion of the heated reacting mass drops into the Sistent with the Stated limitation. body of hot aqueous sodium phenate solution Although the diagram shows the separate ad 3 which is maintained in the still . dition of sodium hydroxide and phenol to the re The temperature of the body of hot aqueous cycle aqueous sodium phenate, it Will be under sodium phenate in the still is kept above 100° C. stood that the sodium hydroxide and the phenol and preferably from 104° C. thru 109° C. By could first be brought together to form sodium reducing the pressure slightly in the distillation phenate and this product then added directly to Zone a temperature in the lower portion of this the recycle aqueous sodium phenate. Alterna range may be used, whereby crystalizing out of tively, instead of adding the sodium hydroxide Sodium Sulfate in the heat exchanger is avoided. and phenol separately to the recycle acqueous Crystalline sodium sulfate which is produced in sodium phenate in line 5, these reactants may be the anisole-forming reaction settles in the hot introduced into the still at a point immediately body of aqueous Sodium phenate and collects in adjacent the point where pipe 5 leaves the still; the conical bottom of the still body. or a product, sodium phenate, formed externally 5 5 Turning now to a consideration of the recovery to the recycle System could be introduced into the of anisole from the vapors leaving still and still at the same point. having reference to the drawing, it will be noted The Sodium hydroxide and the phenol may be first that the vapors pass thru condenser 4 introduced into the System in any convenient 60 Wherein they are cooled and liquefied. The con form. For example, the sodium hydroxide may be densed mixture then flows thru line 5 into sep added in the form of an aqueous Solution, say 50 arator 6. In the separator the condensed ani per cent sodium hydroxide. As for the phenol, it Sole and the condensed water are allowed to sep is conveniently added as the molten product. arate by gravity, the anisole forming the upper The dinnethylsulfate which is to be reacted With layer. This upper layer, the product anisole, sodium phenate to give anisole is introduced into is then withdrawn from the system thru line T. the Stream of refortified aqueous sodium phenate The gravity separation is most readily effected thrue line f2. The advantages of the processes by maintaining the liquids in the separator at of the invention are most fully realized by adding a slightly elevated temperature, preferably be the dimethyl sulfate to a turbulent stream of re O tWeen 25 and 45° C. Water Withdrawn from fortified aqueous Sodium phenate preceding a the bottom of the separator thru line 8 may centrifugal pump so that there is a rapid intimate be discarded, used in subsequent process steps, mixing and local excesses of the dimethyl sulfate or more preferably, as shown in the drawing, is in the reaction maSS are avoided. The ited thru the still level adjuster 9 into Of the dimethyl Sulfate will, of course, vary some still . - 2,529,887 5 6 Considering now the recovery of by-product, added continuously in substantially equimolecu sodium sulfate, which is formed in the reaction lar proportions to at least a portion of the un of sodium phenate with dimethyl sulfate, it will reacted aqueous Sodium phenate to form the be seen, according to the preferred embodiment aforementioned refortified aqueous solution of of the invention illustrated in the drawing, that 5 Sodium phenate. The refortified aqueous solu a slurry of the crystalline sodium sulfate in aque tion is continuously cycled and admixed with ous sodium phenate is withdrawn from the bot the methylating agent, as mentioned above, thus tom of the still and pumped continuously thru forming a cyclic process. The phenol, the alka line 9 into a continuous centrifuge 29. Aqueous line Sodium salt, and the methylating agent are sodium phenate separated from the crystalline () introduced into the System in substantially the sodium sulfate in the centrifuging Step is re Stoichiometric proportions required for the for turned to the still thru line 2. Water used to nation of anisole. wash the solid sodium sulfate in the centrifuging I Claim: Step may also be returned to the still. 1. In a continuous process for the manufacture Other methods for recovering the by-product, of anisole, the StepS comprising adding a methyl Sodium sulfate, may also be used. For example, atting agent for phenol to a stream of refortified the cone bottom of the reactor may be connected a queous Solution of Sodium phenate naintained to an inclined pipe in which is located a conveyer in turbulent fioW, the rate of addition being Such screw adapted for advancing the precipitated that the methylating agent does not exceed its sodium sulfate up the incline counter-current to Solubility in the Solution whereby a liquid react wash water to a point above the liquid level in ing mass is obtained, forming anisole in the the reactor tank and ultimately discharging a stream of aqueous Sodium phenate by passing drained sodium sulfate crystal. the liquid reacting mass thru a heating zone, Although the invention has been described Separating the anisole formed from unreacted . with particular reference to the use of dimethyl - 2. Gueous Sodium phenate, adding phenol and an sulfate as a methylating agent, it will be under alkaline sodiuin conpound Selected from the stood that any one of a variety of inorganic and group consisting of sodium hydroxide and a sodi Organic methyl having a labile methyl un carbonate continuously in Substantially equi group may also be used in the processes of the molecular proportions to at least a portion of the invention. Suitable methylating agents for 3) unreacted aqueous sodium phenate to form said phenol include, for example, a methyl Sulfate refortified aqueous solution of sodium phenate, having the directly attached to the and continuously cycling a stream of the reforti Sulfate radical such as dimethyl sulfate, Sodium fied Sodium phenate for admixture with said methyl sulfate, potassium methyl Sulfate, am methylating agent as aforementioned, said addi monium methyl sulfate, or methyl acid Sulfate; tions of phenol, alkaline sodium compound, and also methyl halides such as methyl chloride, methylating agent being in Substantially the methyl iodide, and methyl bromide; and organic Stoich.Onetric proportions required for the forma methyl esters such as methyl acetate. Of course, tion of anisole. if the methyl acid sulfate is used, it will be 2. In a continuous process for the manufacture necessary to add a stoichiometric amount of al 3. of anisole, the steps comprising adding dimethyl kali to maintain the reaction maSS in the desired Sulfate to a Stream of refortified aqueous Solu neutral condition. tion of Sodium phenate maintained in turbulent Instead of Sodium hydroxide, which was set flow, the rate of addition being such that the out as a reactant in the illustrative processes of methylating agent does not exceed its solubility the invention described heretofore, one may use in the solution whereby a liquid reacting mass is other alkaline or basic sodium compounds, Spe obtained, forming anisole in the stream of aque cifically a sodium carbonate such as sodium car ouS SOdium phenate by paSSing the liquid react bonate or sodium bicarbonate. ing maSS thru a heating Zone, separating the While certain specific processes have been anisole formed fron unreacted aqueous Sodium shown in the foregoing disclosure for effecting O phenate, adding phenol and sodium hydroxide in the separation of anisole from unreacted Sodium substantially equimolecular proportions to at phenate, it will be understood that one skilled least a portion of the unreacted aqueous sodium. in the art may readily employ other techniqueS phenate to fornin said refortified aqueous solution for effecting such separation without departing of sodium phenate, and Continuously cycling a from the Spirit of this invention. For example, stream of the refortified Sodium phenate for ad the reaction mass leaving the heating ZOne may mixture With said dimethyl Sulfate as aforemen be separated into two liquid phases, an anisole tioned, said additions of phenol, Sodium hydrox phase and an aqueous Sodium phenate phase, ide, and dimethyl Sulfate being in substantially and the anisole-phase withdrawn from the cyclic the stoichiometric proportions required for the System. 60 formation of anisole. Reviewing it will be seen that the invention 3. In a continuous process for the manufacture in its broad aspect relates to processes in which of anisole, the steps comprising adding methyl a methylating agent for phenol is added to a chloride to a stream of refortified aqueous solu stream of refortified aqueous solution of Sodium tion of sodium phenate maintained in turbulent phenate maintained in a turbulent flow, the rate 65 flow, the rate of addition being such that the of addition being such that the methylating methylating agent does not exceed its solubility agent does not exceed its Solubility in the Solu in the solution whereby a liquid reacting mass is tion. A liquid reacting mass is thus obtained obtained, forming anisole in the stream of aque and anisole is formed in the stream of aqueous OuS SOdium phenate by passing the liquid reacting sodium phenate by passing the liquid reacting maSS thru a heating Zone, separating the anisole mass thru a heating zone. Next the anisole which formed from unreacted aqueous sodium phenate, has been formed is separated from the unreacted adding phenol and Sodium hydroxide in substan sodium phenate. Phenol and an alkaline Sodium tially equimolecular proportions to at least a por compound selected from the group consisting of tion of the unreacted aqueous sodium phenate to sodium hydroxide and a sodium carbonate are form Said refortified aqueous solution of sodium 2,529,88? 7 8 phenate, and continuously cycling a stream of the the solution, whereby a liquid reacting mass is refortified sodium phenate for admixture with formed, passing the liquid reacting mass thru a said methyl chloride as aforementioned, Said ad heating zone and heating the mass therein to a ditions of phenol, sodium hydroxide, and methyl temperature above about 106° C., flashing the chloride being in substantially the Stoichiometric heated liquid into the vapor space of a distilla proportions required for the formation of anisole. tion zone which contains a body of hot a queous 4. In a continuous process for the manufacture sodium phenate whereby a mixture of anisole and of anisole, the steps comprising adding a methyl water is vaporized and aqueous Sodium phenate sulfate to a stream of a refortified aqueous solu solution from the reacting mass is added to the tion of sodium phenate maintained in turbulent 10 body of hot aqueous sodium phenate in the dis flow, the rate of addition being such that the tillation zone, withdrawing vaporized anisole methyl sulfate does not exceed its Solubility in water mixture from the distillation Zone, con the solution whereby a liquid reacting maSS is densing the withdrawn vapors and separating the formed, passing the liquid reacting mass thru a. condensed anisole from the condensed water, heating zone and heating the mass therein to a adding Sodium hydroxide and phenol continuously temperature above about 106° C., flashing the in substantially equimolecular proportions to at heated liquid into the vapor Space of a distilla least a portion of said body of hot aqueous Sodium tion zone which contains a body of hot aqueous phenate and mixing to form said refortified aque sodium phenate whereby a mixture of anisole ous solution of sodium phenate, and continuously and Water is vaporized and aqueous Sodium phe 20 cycling a stream of the refortified sodium phenate nate solution from the reacting maSS is added to for admixture with said methyl chloride as afore the body of hot aqueous sodium phenate in the mentioned, said Sodium hydroxide and phenol distillation zone, withdrawing the vaporized miX each being added to the hot a queous sodium phe ture of anisole and water from the distillation nate in the proportion of about one no per mol Zone, condensing the withdrawn vapors and 2 5 of methyl chloride added to the refortified aque separating the condensed anisole from the con ous sodium phenate Solution. densed water, adding Sodium hydroxide and 7. In a continuous process for the manufacture phenol continuously in substantially equimolecu of anisole, the steps comprising continuously add lar proportions to at least a portion of said body ing dimethyl Sulfate to a turbulent stream of a of hot aqueous sodium phenate to form said re refortified aqueous solution containing 35 per fortified aqueous solution of Sodium phenate and cent thru 45 per cent by weight of sodium phenate continuously cycling a stream of the refortified the rate of addition being from 0.5 thru 1.0 part sodium phenate for admixture with said methyl by weight of dimethyl sulfate per 1000 parts by sulfate as aforementioned, said additions of Sodi weight of the refortified aqueous solution where um hydroxide, phenol and methyl sulfate being by a liquid reacting mass containing the dimethyl in substantially the stoichiometric proportions sulfate in Solution is formed, passing the liquid required for the formation of anisole. reacting mass thru a heating Zone at a pressure 5. In a continuous process for the manufacture of 15 thru 45 pounds per Sq. inch and heating the of anisole, the steps comprising adding dimethyl maSS therein to a temperature of 108° C. thru sulfate to a stream of a refortified aqueous Solu 115° C., expanding the heated mass tangentially tion of sodium phenate maintained in turbulent into the Vapor space of a distillation zone which flow, the rate of addition being such that the di contains a body of aqueous sodium phenate at methyl sulfate does not exceed its Solubility in a temperature of 104° C. thru 109° C., whereby a the solution, whereby a liquid reacting maSS is rotatory motion is imparted to the said heated formed, passing the liquid reacting mass thru maSS and a mixture of anisole and water is va a heating zone and heating the mass therein to porized While aqueous Sodium phenate solution a temperature above about 106° C., flashing the from the heated mass remains and adds to said heated liquid into the vapor space of a distilla body of aqueous sodium phenate in the distillation tion zone which contains a body of hot aqueous Zone, withdrawing the vaporized anisole-water sodium phenate whereby a mixture of anisole and mixture from the distillation zone, condensing the water is vaporized and aqueous Sodium phenate Withdrawn vapors, separating the condensed solution from the reacting mass is added to the anisole from the condensed water, continuously body of hot aqueous sodium phenate in the dis Withdrawing a stream of aqueous sodium phenate tillation zone, withdrawing Vaporized anisole from the said body of aqueous sodium phenate water mixture from the distillation Zone, con 5 5 in the distillation Zone, adding sodium hydroxide densing the withdrawn vapors and separating the and phenol continuously to said withdrawn condensed anisole from the condensed water, stream in Substantially equimolecular proportions adding sodium hydroxide and phenol continuously and mixing to form said refortified aqueous solu in substantially equimolecular proportions to at tion containing 35 per cent thru 45 per cent so least a portion of said body of hot aqueous sodium 60 dium phenate for admixture with said dimethyl phenate and mixing to form said refortified aque sulfate as aforementioned, said sodium hydroxide ous solution of sodium phenate, and continuously and phenol each being added to the aqueous so cycling a stream of the refortified Sodium phenate dium phenate in the proportion of about 2 mois for admixture with said dimethyl sulfate as afore per mol of dimethylsulfate added to the turbulent mentioned, said sodium hydroxide and phenol 85 Stream of refortified aqueous sodium phenate so each being added to the hot aqueous sodium lution, Withdrawing solid crystalline sodium sul phenate in the proportion of about 2 mols per fate from the distillation zone and introducing mol of dimethyl sulfate added to the refortified Water into the process as required to keep the aqueous sodium phenate Solution. Water content of the body of aqueous sodium 6. In a continuous process for the manufacture 70 phenate in the distillation zone substantially of anisole, the steps comprising adding methyl uniform. chloride to a stream of a refortified aqueous solu WALTER, D. SMUTZ. tion of sodium phenate maintained in turbulent flow, the rate of addition being such that the No references cited, - methyl chloride does not exceed its solubility in 75