CA2044247A1 - Process for manufacturing bisphenols - Google Patents

Abstract

ABSTRACT

A method of recovering or purifying bisphenols, in particular bisphenol A, from crude product prepared in accordance with any prior art process, characterized by the fact that theses crude products, possibly after removal of low boiling compounds and excess phenol, are recovered or worked up from solvents by crystallization from high-boiling aromatic hydrocarbons (HBS) having a boiling point which is above 200°C and below the boiling point of the bisphenols.

H:34262.PAT

Description

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'rhe invention rolatu to a method ~or the production and puriflc~tion of bisphenols by cr~stallization from high-boilin~ aromati~ hydrocarbQns.

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Bi~phenol~ are import~t interm~diates for Uu~ pr~iuctiOn of epoxy, polycarbonate, phenyloxy, polysulfones and other pol)/ostor resins. Bisphenvl A, 2-2-bis (4 dihydroxyphenyl~ propane is an imporlant co~ ercial interlnediAte.
Bisphenol A can be produced by condensin~ phenol with acetone in a molar ratio of 2;1 in the pres~nce of acid ca~alysts. The condens;~ion i~ cu~tomarily effæted with excess phenol in the presenc~ of strongly acid cation e~changeIs or strong acids, possibly in the presence of accelerators, In ~eneral, cation exchan~,er~ bearing sulfonic acid ~roups, sulfuric acid or hydrogen chlonde a~e used as strong acids while nlercap~ans or mercapto acids se~ve as accelerators, The reaclion yields a crude product which, in addition to bisphenol A, unreacted phenol and acetone, the acid ~atalyst, the accelerat~r which was possibly added and the wate~ ~f reaction, ati31 contains undesired byproduct~. These byproducts cons;st, for instancc, of isom~r~ of bisphenol A, c~mplex proclucts~ such as, for instance, the s~called codirners, condensation products su~h as trisphenol or even more bighly condens~d products in ~e form of tarry and high-boiling substanceS as wdl ~s deccmposition product~. The presence of ~hese byprodu~s is ur,desired since they tend to ren~ain in the f~nal p~duct and to cause l2ndesirod discolorgtions. This impairs the usefulne~ of the filul product, even in cases in which panicularly high punty i3 not re4uited. In addition, the decomposition produ~ts prevcnt some of ~he cu~totnary rcaptions of bisphenol A, for instance the further conversion to form polycarbonate~. .
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2 ~ 2 1 7 US Paten~ 2,191,831 diseloses a me~hod of producing very pure bisphenol A
in which bisph~nol A i9 rem~;~ved ~irec~ly in crystallinc form from the cru~e reaction mixture. This procedure is, however, exl~em~ly cumbersome and expensive ~ince it i9 necess~ o wash the crystalline bisphenol A sever~ ~imes. In addition. the bisphenol A
~recipitates only in very small yields.
French Patent 1~374,477 discloses another method for the produc~ion of ~ure bisphenol A in which, first of all, the unreac~d produc~s and only thereaf~er, bisphenol A
are separated by fractional distillation from the crude condensation rni1rture, and the bisphcnol A is fina~ly punfied by e~traction or recry~talli~tion. This method result~ in consider~ble losses of bisphenol ~. Fur~hermore, many exlraction~ or re~rys~allizations are ne~es~ry in order to produce ~ bisphenol of high pur~ty. ~3ven if the distillation is carned out under extremely careful eorlditions, there is a decomposi~ion of ~isphenol A in this process creating new unde~i~eLI impurities which discolor the ~Inal product. Furthermore, ~he bisphenol A cannot be completely distilled off in practice since some eomponent~, in particular bisphenol A i~oMers, haYe v~ry similar boiling points.
By a method described in l~alian Patent 650 774, the bisphenol A is removed by crystalli~ation of its addition p~duct with phenol, In this ca~, a par~ of the desireci product9 remains in the mother liquor of the condensa~ion process ~nd anoSher part rern~ins in the mother liquor o~tained af~er the recrystallization.
Federal Republic of aermany OS 17 93 431 and 20 61 531 teach method~ of purification which are b~sed on the formation of adducts from phenol and ~isphenol, followed by a crystallization step. Fede~al Republie of l3ermany ~S 12 38 ~38 and F~der~l .

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'9~ a6~12 15~21 Z; ~ 212 972 5~187 COHE~I PO~I~a~ll 13 ~0~'~2l~7 Republic of aermany 0~ 17 93 3~4 describe scrubbin~-ex~ction proccsses with org~nic ~olven~s or water. Fe~eral Republic of 13ermany AS ~2 59 346 flnally ~hes a method of crystallization from solvents in which tbe same ~olventg arc used as in Feder3~1 Republie of Germ~ny AS 12 38 038 but th~ temperatures ar~: higher than the boiling points of ~he solvents.

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2~ 7 The object of ~he present invention is to psovjde a ~imple economic melhod for the recovery and/or punfication of ~isph~nols, in particular bisphen~1 A, from crude products prepared in accordanco with any prior art process, characterized by tha fact that these crude prod~uts, po~sibly ~er remoYal oî low boilin~s compounds and excess phenolJ
are recovered or workt:d up from ~olven~ by c~ystalllzation from high-boilin~ ~romatic hydroc~rbons (HBS). Suitable pr0ferred hydrocarbons (~BS) are ~hose containing two or three benzene lin~s which aro connected to ~ch othor dire~sly via mathylene or oxygen and which may bear allyl radicals and/or halo~e~l in the nucleus a~ wdl u ln nlethylene br.id~es, mono and polyaL1cylbenzenesl alkyl and polyallcylindanes, tetralins, hexshydr~naphthalene~, alkyl and polyalkylnaphthalenes, and th~ like.

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'91 36'12 15-~2 ~ ~ 212 972 5467 COHEr~ POHTR~ll 15 2~4~2~7 FIG. 1 is ~ ~chematic illu~tration of the onc cmbodiment of method of the present invention;
FlG. 2 is a schernatic illustration of another embodiment of ~he method of the prcsent illustration; and FIG. 3 ix a schematic illustr~tion of yet another e nbodimcnt of the method of the prosent invention.

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By way of example, men~ion may bo made of the following HBS which are used, for ins~ce"ndll5trially a~ or~anic heat ~iers; mixed is,omcrs, benzyltoluenes (MARLOTHE~M L, Huls AG~, mixed isomeric di~nzyltoluenes (MARLOTHE~RM S, Huls AG) and mixed dimethyldiphenyl ethers (~IPHENYL DT, Bayer AG); solYent~ which are used for carbon-free copy papersl namely alkyldiphenyl~, mixed is4meric monoalkyl ~nd polyalkyl naphthalenes, mixed isomeric mcthyl~utyl~naphthalene, mixed isomerjG
nonylnaphthalene~, tert-butyl-alkyl and polyalkylben~enes, etc.
The solubility of bisphenols in HBS i~ depend~nt on the chemical structurc of the high-boiling aromatic hydrocarbons.
The solu~ility of crude blsphenols with ~bou~ 95-9S% b~sphenol A-conten~ in various HBS's i~ shown in ~he following table:

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I10 3.5 7 0 10.0 120 8.0 1 1 .5 16.3 130 1~.0 140 ~200.0 _ l?,TX ~ tert.-butyl-m-xylene DIPN 5~ Mixed isomeric dii~op~opylnaph~ one~
ML - Mixed isomedc ~nzyllpl~ene3 H~ .p~T 7~

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~' ~ ', ' ' 9~ ~6~1~ 15: ~ ;S ~ 97~ ~4~37 COHFH PONTF~ 17 2 ~ 7 Since Ihe mel~ing point of 2,4-bisphenol isomers is 108C it is advisable to effect the crystallization at a ~emperaturo of 100 to 120C, and pr~ferably IOS lo 115C.
In this way a high purity an~i yield of bisphenol A can be obtained. After concentration of th~ molher liquor, a further crystaJlization can be effected, as a result of which the maximum amounts of bisphenol A are reccwered and practi~ly the entire isomers and impurity are enriched in concen~ ed form and removed.
Thè solu~ility of th~ bisphenol~ in ~ S can ~e increascd or reduced by addi~ion of compounds of similar boilin3~ points: Polyalcohols such ~ ethyleno or propylene glycols increase the solubility and, for example, palaffinic hydrocarbon~ reduce the solubility. ~
l`he mother liquor obta~n~d upon the crys~lization can be conccnt~ated and recrystallized. This recrystallized product can be adde~, for inst.ance, in the initial c~ystalli~ation, ThAe mother liquor of the inilial cArystallization contains praclically all of tho ison~Aers and tri- and higher condensedA compounds, codimers as well as re~u3ifications, in addition to di9solved bisphenol A.
The working up of tho las~ mother Uquor can be effected, for instan~*, by distillin~g off HBS and di~tillative separation of the volatile compounds from th~ r~sidue, The volatile compounds can be conver~ed int~ ~e ~ red bisphenols in a~ordance with the pnor art.

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Por the working up of reaction mixtures, for instanc~ ~he phenol/ketone condensation, the HBS may also be of interes~ and advanta~e for, for instance, th~ ~llowing method steps:
1, Distillati~/e sep~ation of ph~nol ig ~ffe~ted, possibly with secovery of ener~gy Of evap~ration by, for instance, production of stean- ~r by heat exchange, up to practi~ally any desired residual phenol content, usin~ the HBS as fractionating buffer.
l~ndor similar conditions, the phenol cant for example, be separated from bisphenol Alphenol adducts and the bisphenol A recc~Yered, for cxamplet in practically any desirod purity by crystallization f~m HBS.
2. It may be of technical and çconomic nterest to sepalate the bisphenol A fro~n the residue by ~distillation with HBS int for instancot a falling-~llm os tube evaporator at temperatu~es Gf 1~0 ~ 220C and O.S-25 mm Hg. By evaporation with HBS the thormal stabiliiy of bispheool A is increas~ and the condensation takes place without sublimation. The bisphenol A can be obtained from the lique~led condensate in practically ~ny desired punty by one or more crys~lliz~tions.

3. The production of vacuum can be eff~cted by the use of HBS as b~ r liquid for liquid-ring pumps. The consum~l or contam~natod~HBS can po~sibly be worke~ up jointly with oth~r HBS slroams.
The method of lhe present inventio~ rmits the pr~uctlon of bisphcnob in practically any dos~red punty.

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By r~crys~llization from HBS and/or scrubbing with pure HBS vr in countel-current with scrubbing liquor an ullra-pure product can be obtained. The workin~ up of the mother and/or scrubbin~ liquors of the recrystallizadon i~ of rel~tivoly minimal cost.
The fact that the crystallization can be c~rried out under vacuurn at ~emperatutes of more than 1~0C is of ,~reat impor~nce. Th~ coolin~ or condensation of the vapors can be effected with a~r, water, evapo~ation, heat exchange or th~ like. No cooling systems or other e~pensive cooling devices aFe uæ~ such as necessary upon crystallization ftom low- boilin~ solvents.
The present method permits the recoYery of bisphenols from crude products produced in any way.
Processes which opera~ with HCl c)r sulfuric acid a~ catalyst~ yield products having a hi~h content of byproduct~, resins and traces of melal. These impuritie~ cause discoloration of the bisphenols and impair use in the produc~ion of polyrners. In 5uch cases, it may be advisable to effect the preliminary purification by co-dis~illation of the bisphenols with HBS and then to recover the product by crystalliz~,tion from the condensed HBS.
In the case of bisphenol A crude products which are prepared with possibly modified cation exchangers as catalys~s and have a p-p content of more than ~3% and a cvlor index of less t}lan APHA 300, a single crystal1ization from HBS ~ilh, for instance, a toluene after~scrubbing ig al~eady ~uf~lcient in order lO prepare products of a purity of more than 99.7% and an ~PHA of less than ~5.
The concentration of bisphenols in HBS c~ul be substantially ~/aried: Since the solubility of the bi~phenols in HBS increases up to complete Iniscibility at higher .

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tempera~ures, tho concentr~tion is depen~ent practically only on the ~ontent and nature of impurities, visc~ity of th~ solutio:~s, and s~irability of ~he crystal slurry.
The ctystallizin~ of the bisphenols from HB~ ~lulion can be effecteci in various ways. Thus, for instanc~, tho solution can ~uita~ly ~e obtain~d by a~ihtion and then cooled. ln this connection, mosl of the bisphenol crys~lizw a~ a ~ tal slurry and c~n be ~overed from th~ latter by filuation or centrifugin~, for in~nco.
One pr~ferably operate~ with cos)lin~ by evaporation or vapor ~ndensation under vacuum, with controlled or uncontrolled ~uper saturation, with or without crystal bed, and/or circulatory cry~tallization.
The following bisphenols can be pùrified by the method of the proscnt invention: Bisphenol A 2,2-bis ~4-hydroxyphenyl)~p~opane; bisphenol ~ ~,4~bis-hydroxyphenyl-meth~ne; bisphenol Z 2,~bis (hydroxyphenyl)-cyclohexane; l~i~phenol S 4-4 di-hydroxydiphenylsulfone; bisphenol E; 4-4 dihydro~ydiphenyl-eth~ne, e~c.
The crystalline masses obtained by the meth~d of the present invention can ~e freed of the adherent traces of muther li4uor by low-boiling solYents such as ~oluene, benzene, cyclohex~ne, heptane, methanol, ethanol, acetic Acid, etc. And dried, for instance, in vacuum. Water may also bo used as scrubbing agent.
The me~hod of the invention ~an be car~ied out continuously or batchwise.
The method is suitable in par~icular for conlimlous oper~ion1 which can be e~fected in various embodiments, Figure I shows schem~tically ~he recovery of bisphenol A from an anhydrous crude condensation mixture which is free of ~cetone and ca~yst, Here, crystallization is H:3 2~2.P~T

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2 ~ 7 effected in lwo or more crystalliiGat.ions, po~sibly in counter-currenl, from ~BS and the isomers a~ well as other volatile byproduc~ are fre~d of residue (resins) in a thin-film evaporator (LVVA) an~ relumed for isomerization into the cor~densution or ~nducted into another appara~us.
Figure 2 shows schematically the recov¢ry of bisphenol A from a bi~ph~nol Alphenol adduct, in which conneclion the mother liquor of thc preparation of ~he adduct is freed of residues, possibly together with the byproducts of the bi~phenol A crystalli~ation, by distill~tion in a thin-film evaporator.
Fi~ure 3 shows the ~ tillation of bisphenol A with HBS in a falling-filln evaporator~ The vapurs of ~BS and ~isphenol A are cond~n~ed together and worked up in a cr,ystallizer. The residue-containing resin~ and non~volat;le impurities are already removed here. If suitable, they carl further be freed with a thin-~llm evaporator (LUVA) of Ihe traces of the volatile products.
The mother liquor of ~he crys~lization is c~ncenttated, for ins~ance by evaporation, and crystallized in the after-eryslalli~er and the crystals condu~ted into ~he crystsllization .
The moth~r liquor of the after-concent~ation is freed of HBS in an evaporator and the products retum~d to the isome~i~ation.
The crystal mass after, for instanco~ ing wlth pure H~S cat~ be melted with water above 85C and freed of traces of HBS ~y removing them by steam distillation, displacemens of the ~races of H~S with water ~followed by decan~in~ and separation) or by, .

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' 9 1 ~6~ 1 2 1 5 ~ i'7 ~: 1 2 1 2 S'72 54~37 C~HEN PONTFIIl I 22 2 ~ 7 ext~action with, for ins~ance Cs-clo paraffin hydroeasbons. An HBS-free produc~ is then obtained by crystalllzation from wat r.
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25 grams of commercial technical bisphenol A with 97.~æ p-p and 2.40% o-p (not ~ilylatedl no~ corrected) are hea~ed with 75 ~r~m~ of MA2~0THERM L
to a~ut 150C until the so1ution is hvmo~enous. 1~ is then slowly c~oled with agitation, Crystallization talces place at about 110C. The con~ent of the tlaskis filtered off from the mother liquor Ihrough a glass frit at about 1 l0Ch The crystals are washed free of adherent mother li~uor three tlme~ with cyclohexane and dr~e~ in vacuum.
Yield: 19.5 grams ~ 78%
Color: White GC:L; p-p ~.9 FL%
~p 0,1 Pl.,%

The same p~ocedure iS used as in Example I exc¢pt that cooling ~s effected to about 2~-30C, followed by filtratlon and the cry9t~1s are washe~ three tlmes with cyclohexane and d~ed in vacuum.
Yield: 27.78 grams Y 95,12%
Color: White ~ :

GCL:: p-p ~9.8 FL,~6 no~p 0.2 FL% .

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lS ~ram~ of bi~phenol A ~ iJ~ ~xamplo 1 and 50 ,gs~ns of ll~lOTH~RM S
are rapidly distilled in a flask 9~rre~d wjth a ma~ne~i~ rod un~er a vacuum of about lO mm H8 ~nd at ~ tempera~lJre of about 211-230C.
The vapors are condensed (no su~limation) and the cryYtal slurry obta~ned i~
then flltered over a ~glass fri~.
About 13 ~ams of bisphenol A, white, of a purily of a~out 9~.95 PL% p-p a~e obtainod.

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In thi~ example the infl~ence of th~ crys~lizadon temperature on the purity of the products is ~hown.
300 g~ams of crude bisphenol A of 95.~% purity and 2.8% o-p and 1.3%
other impuritjes is heatcd to aboul 140~ in about ~/~ ml MARLOTHERM L.
I~e solution obtained ;n this n~anner~ Is cocled wilh a~itation ~ 11~~, a crystal slu~y being folmed.
The cr~i~tal mass ;s separdte~ with a cen1nfilgo pr~ùea~ o a~out 110C and .
the crystals are thereupon washed with to~ueno. 210 grams of ol-y8tals of a punty of 99~85% are ob~ine~
Upon co-~ling to I05C and separation at a temperature of ~bout 105VC, a product of 9~.4% purity is obt~ined.

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Claims (14)

WHAT IS CLAIMED IS:

1. A method of recovering or purifying bisphenols, in particular bisphenol A, from crude product mixtures, comprising: treating crude bisphenol or phenol adducts with aromatic hydrocarbons having a boiling point which is above 200°C and below the boiling point of the said bisphenols; separating said phenol in the presence of solvents by destillation; and recovering said bisphenols by at least one crystallization.

2. The method according to Claim 1, wherein said hydrocarbons are selected from the group consisting of mono and polyalkylbenzenes.

3. The method according to Claim 1, wherein said hydrocarbons are selected from the group consisting of hydrocarbons containing two or three benzene rings connected directly to each other via methylene or oxygen and, optionally, bear alkyl radicals and/or halogen in the benzene rings as well as in said methylene bridges.

4. The method according to Claim 1, wherein said hydrocarbons are selected from the group consisting of alkyl, naphtalenes, polyalkylnaphthalenes, tetralins, hexahydronaphthalenes, alkyl and polyalkylindanes.

5. The method according to Claims 1, additionally comprising the step of adjusting the bisphenol solubility by adding mixtures of two or more compounds selected from the group consisting of aliphatic hydrocarbons, aliphatic polyalcohols, aliphatic polyethers and polyhydroxy ethers.

H:34262.PATT

6. The method according to Claim 1, wherein said bisphenols are distilled with solvents as carrier vapor and then recovered by said crystallization.

7. The method according to Claim 1, wherein said phenol is separated by distillation while recovering the heat of condensation by production of steam or heat exchange.

8. The method according to Claim 1, wherein said crystallization is carried out in one of cooling crystallizers, evaporation crystallizers and spray crystallizers.

9. The method according to Claim 1, wherein said crystallization is carried out in several steps, in parallel flow or counter-flow, optionally including recrystallization.

10. 2,2 bis (4-di-hydroxyphenyl) propane prepared in accordance with the method of Claim 1.

11. 2,2 bis (4-di-hydroxyphenyl)cyclohexane prepared in accordance with the method of Claim 1.

12. The method according to claim 1, wherein said crystallization is carried out at temperatures of 100 to 120°C.

13. The method of Claim 12, wherein said crystallization is carried out at temperatures of 105 to 115°C.

14. A method according to Claim 1, additionally comprising the step of melting said crystals with water above 85°C optionally after washing with pure solvents, removing traces of HBS; and then crystallizing from water.

H:34262.PAT