CA1077523A - Process for producing butanediol or butenediol - Google Patents

Abstract

Abstract of Disclosure:
A process for producing butanediol or butenediol by hydrolysis of diacetoxybutane or diacetoxybutene is disclosed wherein the raw material acetic diester and water are mixed with a portion of the hydrolysis product from which acetic acid and water have been removed to form a uniform aqueous solution to be fed to the hydrolysis stage whereby the hydrolysis reaction proceeds smoothly without using an excessively large amount of water, the byproducts are utilized effectively and energy consumption is reduced.

Description

~775~3 ~ his invention relates to a process for producîng butanediol or butened.iol and, in more particu1ar7 to a process for producin~ a diol comprisin~ subject.ing acetic diester of 1,4-butanediol or 1,4-bute~ediol-2 to hydrol~3is to obtain the corresponding butanediol or but.e~ed~ol.
It has already been k~ow~ that 1,4-but~nediol i~
useful as an or~anic solvent or a raw material for tetra-hydrofuran from which an organic solvent, such as tetra-methylene glycol or ~-butyrolactone, is deri~ed ~d it 10 has al90 bee~ practiced tha~ 1,4-diacetoxyb~tane is subJected to hydroly~is to obtain 1,4-butanediol.
From our intensive study o.f the production of a glgcol, especiallg 1,4-butanediol or 1,4-bute~ediol-2, by hydrolysis of an acetic diester of a glycol, it has been fo~nd that 1,4-diacetoxybutane a~d 1,4-diacetoxybutene-2 are im~iscible with water, but hydrol~sis.products thereof are miscible with water, and, in particular, the solubilit~ o~
such acetic diester in water increases in the prese~ce of the diol a~d ~onohydrox~acetoxybutane or mo~ohydro~yacetoxy~utene which is partial hydrolysis product of the diester, and, in consequence, a uniform solution of diacetic ester in water can be obtained. It has also been fou~d that the raw material acetic diester, i.~ partial hy~rolysis product monohydroxyace~oxybuta~e and the hydrolysis product diol form an azeotropic mixture, and, accordingl7~ if ~uch hydrolysis products are recovered by aæeotropic di~tillation from the reaction product and xecirculated together with the raw ma~erial to the hydrolysis st~ge, the e~tire proce~
c~ conveniently be carried out. ~urthermore~ it has bee~
found that, b~ effecti~g the h~droly6is i~ t~o sta~les a~d ~3 1~77~i2~

1 recirculating a portion of the resulting hydrolysis products to predetermined hydrol~sis stages, the efficiency of the process can be improved.
An object of this invention, accordingly, is to provide : a process for producing 1,4-butanediol or 1,4-butenediol-2 in high yield by subjecting 1,4-diacetoxybutane or 1,4-diacetoxy-butene-2 to hydrolysis.
.i Another object is to provide a process for producing ~ 4-butanediol or 1,4-butenediol-2 by hydrolyzing 1,4-diacetoxy- ~;
;; 10 butane or 1,4-diacetoxybutene-2 wherein the hydrolysis is effect-~3 ed in a uniform aqueous system and an azeotropic mixture re-covered from the hydrolysis product is recirculated to the . hydrolysis stage thereby allowing to proceed the reaction smooth-ly, utilizing by-products effectively and saving enerqy.
.~ Further objects and advantages will appear from the following description taken together with the accompanying draw-ings in which: -Figures 1, 2 and 3 are flow sheets of three alternate ;l apparatus s~itable for the practice of the process according to this invention;
Figures 4-A and 4-B are equilibrium diagrams of the azeotropic mixture of 1,4-diacetoxybutane (1,4-DAB) which may contain l,2- and 1,3-isomers and 1,4-butanediol (1,4-BG) in which the horizontal axes represent the mol fraction of 1,4-DAB
in the liquid phase ~x:1,4-DAB) and the vertical axes represent - the azeotropic temperature and the mol fraction of 1,4-DAB in .
the gas phase (y:1,4-DAB), respectively; and Figures 5-~ and 5-B are equilibrium diagrams of the azeotropic mixture of l-hyaroxy-4-acetoxybutane (1,4-HAB) which may contain 1,2- and 1,3-isomers and 1,4-butanediol (1,4-BG) in ~j .

i .:, .,,, j - 1C~7~Z3 1 which the horizontal axes represent the mol fraction of 1,4-HAB
in the liquid phase (x:1,4-HAB) and the vertical axes represent the azeotropic temperature and the mol fraction of 1,4-HAB in ~; the gas phase (y:1,4-HAB), respectively. ., It has already been known that 1,4-diacetoxybutene-2 ~ .
and 1,4-diacetoxybutane which are the raw materials used in this invention are synthesized from butadiene and acetic acid by various oxidation acetoxylation processes. For example, 1,4-.;
diacetoxybutene-2 is produced by reacting 1,4-butadiene, acetic acid and oxygen or an oxygen~containing gas in the presence of a palladium series catalyst through any process of a fixed bed, ` a fluidized bed or a suspended catalyst system. Examples of the .. ` .
~ catalyst which may be employed in this reaction include, for ... .
example, a homogeneous liquid catalyst, such as a Redox system of a palladium salt and a copper salt, and a solid catalyst of ~., ~` a metallic palladium, platinum, rhodium, iridium or ruthenium or a salt thereof or a . . .
.~' ~ 20 .~ ' ' .
, .
.
~ .

-3a-.. ,.
!

~77523 combination OI such metal or salt with, as a cocataly~t, metallic copper, silver, zinc, nickel, chromium, iron1 ~` cobalt, cadmium, tin, lead, molybdenum, tu~gsten, antimony, tellurium, selenium, bismuth, an alkali metal or an alkaline e~rth met~l or a salt -thereof; în particular, . r a supported catalyst consi~ting essentially of metallic palladium ~nd, as a metallic cocatalyst, a~ least one :~ member selected from bi~muth, selenium, antimony and tellurium. From the acetoxylation pr~duct thus obtained, a mixture of diaceto~ybutenes such as 1,4-diacetoxybutene-2 ;
a~d ~,4-diacetoxybutene-1 is separated by distillation and is u ed as the raw material in the reaction accordi~g to this i~vention; if desired, ~uch mixture of diacetoxybutenes i8 subjected to isomer sep~ration before use. Alternativel~, 1,3- and 1,4-dichlorobutenes, acetic acid and sodium acetate are reacted in the prese~ce of a metal ~alt catalyst to ; obtain a mixture of diacetoxybutenes which may be used a~
such i~ the proces~ according to thi~ inventio~.
~iacetoxybutanes are produced by ~ubjectiug the mixture of diacetoxybutenes thus obtained to hydroge~ation in the pre~ence of a palladium or nickel catal~t, and may be u~ed in the foxm of either a mi~*ure or a ~i~gle isomer of 1,4-, 1,2- or 1,3-diacetoxybutane separated.
In the hydrogenatio~ of -the diacetoxybute~e, butylacetate may often be byproduced depe~ding upon the performance o~ the catal~st employed.
It is preferable to u~e diaceto~ybutan~ ha~i~g a purity o~ more tha~ 99% which ma~ be o~tained by7 for e~ample, after degasification1 subjectillg the crude diaceto~ybutane to distillation in a column under such ~()77SZ3 , :` ~

conditions a~, for example 3 the number o~ theoretical plates being from 15 to 25, at a bottom temperature of below 190G., under a head pressure of from 50 to 200 Torr~ and at a reflux ratio of from 1 to 5.
According to this invention, the diacetox~butane or diacetoxybutene is contacted with a solid acid catal~st bed to effect hydrolysis. ~he solid acid catalyst may be æilica-alumina, activated clay, silica or a catio~ ex~hange ~: resin; in particular, a cation exchange resin i~ preferable~
because it gives a higher hydrolysis rate and produ~es ;-, ; less amount of byproducts, t~pically tetrahydrofuran.
A typical ca~onexchan~e resin is a sulfonic acid type strong acid cation exchange resin the matrix of which i~ a copolymer of ~tyrene and divinyl benzene and it may be either gel type or porous type, f or example, SE lB*
SE 103* SK 106, PE 206, PK 216 or P~ 228*aYailable from Mitsubishi Chemical Industries ~imited~ ~ok~o, ~apan.
The hydrolysis reaction is carried out at a temperature of~ in general, from 30 to 120C, preferably 40 to 100C and more preferably 50 to 80C. The lower the temperature, the slower the reaction rate i8, SO too low a temperature requires a large amount of the catal~st;
on the other hand, at too high a temperature7 large amount8 of byproducts such as tetrahydrofura~ and dihydrofuran are formed to decrease the ~ield of the desired produc~0 ~or ex~mple, where diacetoxybutane is hydrolyzed u~i~g "~K lB"
: catalyst at a te~pera~ure of below 100C and o~ 120C, at .~: most about ~/0 and 2~% of tetrahydrofuran ~or buta~ediol are formed, respectively, whereas at a temperature above 140C a half or a maJor amount of the product is the * Traae Mark , ~,~

~775~Z3 ' byproduct tetrahydrofuran~ ~urther, within t~e above temperature ra~ge, degradatio~ of the cation exchange resin is prevented and dissolution of the resin is also reduced.
~ he pressure under which the reaction is carried out i~ not critical but a pressure under which boiling or undua bubbli~g of dissolved gas i8 prevented is preferred ana, in general, such pressure is from atmospheric to 10 kg/cm2G~ -,; .
~ 10 A stoichiometric or excess amount of wa-ter to , ~
diacetoxybutene or diacetoxybutane is conveniently used, since the water is a reactant and also a solvent. In order to have the re~ction proceed smoothly, it is preferred to conduct the reaction in a uniform aqueous sy~tem. ~he raw material aceto~ybutane or diacetoxybute~e ca~ dissolve in an excessively large amount of water to ,~ form a uniform aqueous solution, and the larger the amount of water, the higher the conversio~ of the reactio~s; but too much water requires a large amount of heat in recovering butanediol or butenediol from the reactio~ product and this is uneconomical. On the o~her hand, too little water decreases the conver3ion and, in co~sequence, ~he recovery of butanediol or butenediol becomes difficult. Thus, according to this invention, the molar ratio of water to diace~oxybutane or diacetoxy-bu~ene ranges, i~ ge~eral, from 2 ~o 100:1, pre~era~ly 4 ~o 50:1.
An embodiment of the process according to this in~ention will be explai~ed referrin~ to the accompanied ~0 drawing.

~77~ii23 , I~ order to ~orm a unifo~m aqueous solution to be supplied to the hydrolysis stage without using an excessively large amount o~ water and to effect the reaction ~moothly according to this invention, it is essential that the raw material di~cetox~butane or diacetoxybutene be mixed with ei~her (1) a portion af the reaction product from which water a~d acetic acid have been removed or (2~ a~ azeotropic mixture of acetic diester, monoh~droxyace~ic ester and diol obtained ~rom the reactio~ product from which water and acetic acid have been removed.
Although the removal of water and acetic acid from the reaction product may be effected in separate distillation stages, it should be noted that, ir the reaction product is mai~tained in a state of high acetic concentratio~ at high temperature, there is observed a reYerse reaction with the result o~ loweri~g the ~ield of the desired diol. Thus, it i~ pre~erable to distil off ~ubstantially al~ of the water and acetic acid simultaneously. ~urther, in the distillation at a bottom temperature of distillation column above 210C, the conversion of l,4-butanediol into undesirable tetra-hydrofuran is accelerated, so it is convenient to effect the di~qtillati on at a temperature, in ~eneral, up to 200C, p~eferably up to 190C.
A por~ion of ~he reaction product from which water and acetic acid have been distilled out is recirculated to the hydrolysis stage after being mixed with the raw material acetic diester and water. The amount to be 30 recirculated may var~ depending upo~ reaction conditions, ,.. : , .:

5~3 s ` ~

, such as, the reaction temperature, the proportion of component~ in the reaction system and the conversion of reaction. Further, it is co~venient that the water separated by distillation from the water-acetic acid fraction be used in the hydrolysis stage in order to operate the process in a closed system; in this case, : depe~ding upo~ distillation condi~ion~, the wa~er o~ten co~t~ins some acetic acid which facilitates the formation of a uniform aqueous solution of the feed material. For thiæ rea~on, the amount to be recirculated cannot be standardized and is u~ually from 0.5 to 10 times, preferably 1 to ~ times b~ weight that o~ the sum of water and the raw material acetic diester.
Where an a~eotropic mixture containing acetic diester, monohydroxyace~ic ester a~d diol sep~rated from the reaction product from which acetic acid and water have been removed is recirculated to the hydrolysis stage, the amou~t to be recirculated is usually le~ t~a~
the above ca~e and, in general, from O.05 to 10 times, preferably 0.1 to 1 time.
In Figs. 4-A and 4-B~ the equilibrium of the a~eotropic mixture of 1,4-dîacetoxybutan0 (1,4-DAB) which ma~ contain 1,2- and 1,3-isomers and 1,4-butanediQl (1,4-BG) is given and the horizontal axes represenk the mol fraction of 1,4-~AB in the liquid phase (x:1,4-DAB) and the Yertical axes repre~ent the azeotropic temperature and the mol fraction of 1,4-DAB in the gas pha~e (y:1,4-DAB), respectively.
Fig~. 5-A and 5-B are the equilibrium of the azeotropic mi~ture of 1-h~droxy~4-acetoxybutane (1,4-HAB) .. ... ....

7~i23 .

and buta~ediol similar to those of Figs. 4-A and 4-B.
The con~a~ts f~l2 and A~l.according~o~ Wil80n ' s ~ equatio~ of the 1,4-diacetoxybu~ ne~1,4-but~nediol system : are 0.407 and 0.354, respecti~ely. ~he Wilson'~ equationis disclosed in the Journal of ~merican Chemical Society~
Vol. 86, p 127 ~1964) by G. M. Wilson to which the reference of this specificatio~ is made.
~hus, the azeotropic distilla~ion is conveniently carried out using a dist~llation column having the number of theoretical plates of from 20 to 90 a~d operated at a bottom temperature of from 150 to 200C, under a head pressure of from 10 to 200 mmHg, preferably 30 to 100 mmHg and at a reflux ratio of from 1 to lOt preferably 2 to 5.
Where the raw material 1,4~diacetoxybutane or 1~-diacetoxybutene-2 contains 1,2- and 1,3-isomers, the di6tillation of the reaction product is conducted 80 that 1,2- and 1,3-diols are distilled out as overhead, while the l,4-diol product is recovered as a side stroam, and the distillation column is oper~ed at a reflux ratio o~
from 2 to 10, preferably 3 to 6.
I~ the raw material consist~ es~entially of 1,4-diacetoxybutane or 1~4-diaceto~ybutene-2, the a~eotropic mixture is directly recirculated to the hydrol~sis stage~
0~ the other hand, if the raw material contains isomers~
acetic acid a~d material~ having boili~g poi~ts lower than acetic acid are separated from ~he hydroly~is product by di~tillation in the ~ir~t di~tillatio~ colum~, and the residue is subjected to an azeotropic distillation in the ~econd distillation column to obtain a mixture containing monohydroxyacetic ester and acetic diester consisti~g of ~: _ 9 _ .~

1~37~5Z3 ; 1,4-, 1,2- and 1,3-isomers and the mixture is recirculated to the hydrolysis stage after separating 1?2- and 1,3-isomers.
~rom a practical point o~ ~iew, however, it is convenient that such isomer separation be effected by removing 1,2- and 1,3-isomers as an overhead and 1,4-isomers o~ the acetic diester, monohydroxyacetic ester and diol as a side stream in the second colum~, the latter being reclrculated.
Accompanying drawings of Figs. 1 to ~ illustrate flow sheets of a~ apparatus suitable for the practice of the process accordi~g to this invention.
Embodiments of this invention will be explai~ed hereunder referring to the drawing~. Although the embodiments are directed to the production of butanediol, it should be understood that butenediol is also equaIly produced by changing the raw material to diacetoxybutene.
Referring to Fi~. 1, I represents a hydrolysis reactor which contains a solid acid catalyst bed, for example, preferably a sulfonic acid t~pe cationic excha~ge resin, and III represents a distillation column. The raw material acetic dies~er and water i~ ~upplied via pipe lines 10 and 12 to the reactor I while the h~drol~sis product is recirculated via pipe line 22 to form a uniform aqueous solutio~. In order to facilita~e the mixing of them, it is convenient to provide~ for example, a di~solvi~g ~ank with a ~tirrer before the reactor, or a stirri~g device or a ~tatic mixing device in the pipe line con~ecting : with the reactor. Alter~atively, trays or a packed layer 30 may be provided in the upper sp~ce of the reactor.

.: - 10 -,. . ,,. ,, . : .

.
~he space velocity of the liquid reactant3 to be supplied to the reactor ma~ vary depending upon, ~r example, the proportion of the acetic diester and wa~er and the reaction temperature, and ~his value is, i~
general, ~rom 0.05 to 10 L~ hr], preferably 0.2 to

2 [~/~ hr~
'~he reaction product which contai~s u~reacted raw material, monoes~er fo~med by partial h~drol~sis and diol and acetic acid formed by hydroly~is is dischar~ed from the reactor Yia pipe li~e 14 ~ollowed by passing throu~;h anion exchange resin ~essel V to remove bisulfite ion dissolved from the catio~ excha~ge resin and transferring ~ia pipe line 16 to distillation.column III. In the distillation column, the water and the acetic acid are distilled off from the top ~ia pipe line 18 while the residue is discharged via pipe li~e 20, a portio~ of said residue being recir-culated to the h~drolysis reactor via pipe line 22 aad the remaining portion being supplied via pipe line 24 to a subsequent processing stage (not shown), for example, thP di~tillation of diol as well as of the unreacted diester ana the acetic monoester partial hydrolysis product, the latter two, then t bei~g recirculated to the reactor, if desired.
Fig. 2 shows another embodime~t in which distillatio~
:25 of the reaction product is ef~ected in two columns. T~e suppl~ of the reactants to the reactor and the hydrolysis ; are co~ducted in way similar to those o~ Fig~ 1.
~he raw material acetic diester, water and the recirculati~g hydrolysis product are supplied via pipe lines 10, 12 and 22 to hydrolysis reactor I and the ~0775;Z3 hydrolysis product is supplied, i~ turn, via pipe line 14 ~o anion exchange resin vessel V and via pipe line 16 to first distillation column IIIg from the top of column III, acetic acid, water and lower boili:ng ~aterials than acetic acid are distilled out through pipin~ 18, while the residue is discharged from the bot-~om and transferred via pipe li~e 20 to second distillatio~ colum~ IV. In the ~econd column, an azeotropic mixture containing acetic diester, monohydroxymonoacetic es~er and diol is removed from the top and is recirculated via pipe line 22 to the hydrol~æis reactor. Where the reaction product contains 1~3- and 1,2-isomers, a fraction containing mainly 1,2-: and 1,3-isomers i8 distilled out from th~ top while a fraction containing mainly l,~isomers is removed as a side stream which is recirculated via pipe line 26 to the hydrol~sis reactor. The residue oP the seco~d colum~
is di~charged from the bottom via pipe li~e 2~ and is supplied to a subseQuent processi~g stage (not sho~n), for example, distillation or extraction to obtain the diol product.
Fig. 3 shows still another embodiment which is mcst suitable for this inventio~ from the point of view of commercial practice. ~his embodiment involves two-stage hydrolysis. ~he first sta~e hydrolysis product is sub~ected to the second hydrolysis after removing acetic acid thereby increasing the conversion of hydrolysis remarkably .
To the first h~drolysis stage is supplied aqueous acetic acid recovered and recirculated from the second acetic acid distillation column and to the second hydrolysis -~ - 12 -.. , .. 1, ~77~i23 stage are supplied the second ~cetic acid distillation column residue contai~ing ace~ic diester, monohydroxy-acetic ester and diol and a fraction containing mono-hydroxyacetic ester and acetic diester recovered from the unreacted raw material recovery colum~.
In Fig. 3, I and II are firs~ and second hydrolysis reactor~ III and I~ are first and second acetic acid distillation columns, VI is a water-acetic acid separation column, VII is an unreacted raw material recover~ column a~d VIII is a rectifying column. In the hydrolysis reactors, a solid acid catalyst, such as sulfonic acid type cation exchange resin is packed.
~ he raw material dlacetoxybutane, water and aqueou~
acetic acid recovered from the second acetic acid distillatio~
column are supplied via pipe li~es lO, 12 and 28, respecti~ely, and mixed to form a unifor~ aqueous feed which is supplied to fir~t hydrolysis reactor I. The space velocit~ of the feed materials to the reactor is maintai~ed at a level similar to that of Fig. 1. ~he reactio~ produc-t from the ~irst reactor is supplied via pipe li~e 16 to first acetic acid di~tillation column III. From the top of the first column, a fraction containing mainly water and acetic acid is distilled out and transferred via pipe line 18 to water-acetic acid separation column VI to which is op-tionally supplied via pipe line 30 an acetic acid fractionrecovered from other reactlon system, such as an aceto.xyla-tion system. Acetic acid is recovered from the bottom of separation column via pipe llne 32 while a water fractio~
i~ recovered via pipe line 34 as a side stream and a low boiling ~raction containing mainly tetra~ydrofura~ is ~C~775;~3 removed from the top ~ia pipe line 36. Where the xaw material contains bu~ylacetate which is a b~product in the productlon of diacetox~butane b~ hyd:rogenation of diacetoxybutene, the overhead containing ~ut~la~etate i5 separated into an aqueous layer and an oily la~er, and the latter is convenientl~ recirculatea to the second distillation column.
~he water fraction recovered as above is supplied via pipe line 34 to second hydrolysis reactor II a~ter being mixed wit~ the first acetic acid distillation column residue co~taining mainly acetic diester, monohyaroxyacetic ester and diol supplied via pipe line 20 and with a side stream from the unreacted raw material recovery column co~taining monohydroxyacetic ester and acetic diestex supplied via pipe li~e 38.
~he reaction product from the second reactor is supplied via pipe line 40 to second acetic acid distillation column IV in which substantially all of the water and ~cetic acid is distilled off from the top and recirculated to the fir~t reactor via pipe line 28. In general, because the acetic acid formed in the first hydrolysis stage has been removed in the first ace~ic acid distillation column, the acetic acid prese~t in this fraction i5 derived ~rom the second hydrolysis and has a conce~tration of from about 7 to about 14% by weight. ~his acetic acid within such co~ce~tration ran~e is capable of forming a uniform a~ueous solution with the reacta~ts to be supplied to the ~eco~d h~drolysis stage and does not adversely affect the hydrolysis reaction.
The residue of the second distillation colu~n - 14 _ ~1~775~3 contains mainly 1,4-butanediolt 1,4-diacetoxybutane and l-h~droxy-4-acetoxybutane and is transferred via pipe line 42 to unreacted raw material recovery column VII.
From the top of the recovery column9 a fraction containing diacetoxybutane, monohydrox~acetoxybutane a~d a small amount o~ butanediol is distilled off a~d recirculated to ~he second hydrolysis stage. Eowever, wh~re the liquid feed contains 1,4~isomer as well as 1,2- and 1,3-isomers, a fraction containing mainly 1,2- and l,~-isomers is distilled off from the top and a fraction contai~ing 1,4-isomers of unreac~ed acetic diester and monoh~droxy-acetic ester is removed as a side stream which is recir-culated via pipe line 38 to the second hydrolysis stage.
~he residue of the recovery column is ~upp~ied via pipe line 46 to rectifying colu~n VIII. ~he 1,4-butanediol product of a commercial grade i~ recovered as a side stream via pipe line 48, while the overhead is recirculated via pipe line 50 to the recovery column and the residue containing high boiling fraction is removed via pipe line 24 and subjected ~o a subsequent recovery process (not ~ho~n), if required.
As mentioned above, according to this invention the reaction is e~fected using a uniform aqueous solution prepared by mixing the ra~ material acetic diester, mono-hydrox~acetic ester, diol and optionally acetic acid, wi~h the result that the reactio~ proceeds 3moothly, the co~version of reaction is increased, the raw ~aterial i~
e~fectively utilized, whereby the desired product diol is obtained in high yield.
Further g if the proces~ accordi~g to this in~ention ~ ~775;~3 is carried out i~ two-stage h~drol~sis, each of various the fractions recovered from the dis~illation stages is recirculated to the specified preceding ~h~drolysis stages;
thus, it is possible to effectively utilize acetic diester and monohydrox~acetic ester by recirculation, a~d thus to have the reaction proceed smoothly in a uniform aqueous solution a~d to achieve high conversion of reaction.
Moreover, this embodiment can sa~e energ~ and is commercially useful in comparison with a process in which hydrolysis of acetic diester is e~fected in a single stage and the product diol is recovered from the ~ !
hydrolysis product b~ di~tillation.
~his invention will be explained in detail by means of Examples. However, it should be understood that this invention is in ~o way limited by these Examples.
Example 1:
In this ~xample, the process was carried out utilizing the apparatus illustrated in Figo lo The reaction vessel was made of stainless steel SUS 316~ with an inner diameter of 10 cm and a length of 80 cm and packed with 3.0~ of cation exchange resin, SK lB H type available from Mitsubishi Chemical Industries ~imited, ~okyo, Japan, to make a bed thickness 46 cm.
To the reactor were supplied downwardly 1,4-diacetoxybutane, water and the recirculating residue of the distillation column at a rate of 209.0 g/hr, 394.9 g/hr ~nd 1177.5 ~/hr, ~espectively, at a temperature of 60C after being mixed them in the supply tube. The liquid hydrol~sis pro~uct was passed through a vessel packed with 0.5R of anion *
exchange resin, WA-20~ available from Mitsubishi Chemical -;~ * Trade Mark ~L0~7~23 Industries ~imited, and transferred t.o the distillation column which was made of stainless steel ~US 316L with an inner di~meter of 40 mm and a length of 5 m and packed with 7 x 7 mm porcelain Raschig rings. ~he liquid product was supplied at 1 m below the top of the distillation column operated at a bottom temperature of 175C, under a head pressure of 100 Torr. and a reflux ratio of 2.1, and the overhead a~d the residue were reco~ered at a rate of 472.6 g~hr and 1308.4 gJhr, respectivel~.
~he composi~ion of the residue was as follows:
1,4-diacetoxybutane 7.~% (by weight) 1,4-hydroxyacetoxybutane 43.~/o 1,4-butanediol 49.~/0 A portion of the residue was recirculat~d to the reactor at a rate of 1177.5 g/hr and the remal~der was ~upplied to a further purification syE;tem to separate and recover 114-butanediol.
By the above continuous operation, the proportion of 1,4-buta~ediol supplied to the purification system was 59.3% molar on the basis of the raw material diacetoxybutane.

~he hydrolysis rea¢tion was carried out accordi~g 25 to procedures similar to those of Example 1 excepti~g that no liquid reaction product waæ recirculated; the~
at the inlet of the reaction ves~el, two liquid phaseæ
were observed and the reaction did not proceed ~moothly~
The proportion of 1 ,4-butanediol supplied into the purification system was only 10. 3% molar on the ~asis ... .. .

~77523 o~ the raw material diacetoxybutane.
l~cample ?:
~ he procedures of Example 1 were repeated excepting that 1,4-diacetoxybutene-2 was used instead of the dia¢etoxy-butane. ~here was observed a uniform liquid feed suppliedto the reactor and the proportion o~ 1,4-bute~ediol-2 supplied to the purification system was 58.3% molar o~
the basis o~ the raw material.
Comparati~e E~am~le 2:
Procedures similar to those of Example 2 were followed excepting that no liquid residue was recirculated from the distillation column; ~hen at thq inlet of the hydrolysis reactor the feed wa3 separated into two phases and the reaction did not proceed smoothly. ~he proportion of 1,4-bu-tenediol-~ supplied to the puri~ication s~stem was only 9.~0 molar on the basis of the diacetox~bute~e~
EXam~le 3:
~he process was carried out according to Example 1 but the r~w material diacetoxybutane contained 13.3% of 1,2-isomer a~d 1.3%, by wei~ht, of 1,3-isomer.
` ~he proportion of 1,4-butanediol supplied to the purification system was 58.y/o molar.

ln this Example, the process was carried out using the appara~us illustrated in ~ig. 2 in which the hydrolysis -~ reactor and the anion exchange resin vessel were same as used in Example 1.
To the reactor were supplied downwardl~ 1,4-diacetoxybutane, water and the recirculating liquid from the second distillation column at a rate o~ 399.5 g/hr, ~7~f SZ3 687.8 g/hr and 839.4 g/hr, respectively, a-t a temperature of 60C after being uniformly mixed in t:he supply tube.
~he liquid reaction product was passed t:hrough a vessel packed with 0.5~ of WA-20 anion exchange resin and supplied continuously to the first distillation column which wa~ made of stainless steel SUS 316~ ~rith an inner - diameter of 40 mm and a length of 5 m and pac~ed with 7 x 7 mm porcelain Raschig ri~gs. The supply of the feed was made at 1 m below the top of the column operated at a bottom temperature of 174C, under a head pressure of 100 ~orr. and at a re~lux ratio of 2 to obtain an o~erhead at a rate of 880.9 g/hr and a residue at a rate o~
1045.9 g/hr. The composition of the residue was as ~ollows:
1,4-diacetoxybutane 20. ~h (b~ weight) l-hydroxy-4-acetoxybutane 52. ~h 1,4-butanediol 27.3%
. ~he residue was tra~sferred to the second distillation column which was made of stainless steel SUS 316L with an in~er diameter of 30 mm a~d a length of 10.5 m and packed with Dickson packings (60 mesh and 60 mm) and operated at a bottom temperature of 176C, under a head pressure of 7~ mmHg and at a reflux ratio of 2Ø
An overhead having the following compositi on was obtained at a rate of 839.4 g/hr and wa~ recixculated to the reactor:
1,4-diacetoxybutane 25.8% (by weight) l-hydroxy-4-acetoxybutane 64. 7%
1,4-butanediol 9.~/0 Also, a liquid residue contai~ing 99.6% by wei~ht .* Trade Mark .'~i , .

of l,4-butanediol was obtained at a rate ol 206.5 g/hr.
~hus, the yield of 1,4-butanediol recovered as the product was 99.5~/0 molar o~ the basiæ of the raw material 1,4-diacetoxybutane.
Similar procedures wexe repeated using 1~4 diacetoxybutene_2 ~ d of the 1,4-diace~o~ybutane to obtain similar results.
Comparative~Exam~le~4:
The process was carried out following the procedures of Example 4 excepting that no overhead from the ~econd column was recirculated to the reactor; then there wa~
observed phase separation of the feed at the inlet o~
the reac~or and the reaction did not proceed smoothl~.
~he yield of 1,4-butanediol recovered from the ~econd column was onl~ 13.2% molar on the basis of the raw material 1,4 diacetoxybutane.

In this Example, ~he raw material was 1,4-diacetoxybutane containing l~Z- and 1,3-isomers and the process was carried out utilizing the apparatus of Fig. 2 according to procedures similar to those of Example 4 excepting -that the fraction recirculated to the reactor was a side s-tream frvm the second distillation column.
The feed materials supplied to the reactor were (1) a mixture containing 90.1% of 1,4-diacetoxy~utane, 8.~o of 1,2-diacetoxybutane a~d 0.4%, b~ weight, of 1,3-diacetoxybutane at a rate of 403.2 g/hr, (2) water containing 11.5% by weight of ace-tic acid at a ra~e of 706.8 g/hr and (3) a side stream ~xaction containing 1~775Z3 1,4-diaceto~ybutane1 1-hydroxy-4-acetoxybut~ne and 1,4-butanediol which was removed at 2.5 m below the ~op o~ the second column operated at a reflux ratio of 80. ~he o~erhead of the second column co~tained 1,2-a~d 1,3-isomers.
~ he yield of 1~4-butanediol recovered from the second colum~ a~ a residue was 99.46% molar on the basis of the 1,4-diacetoxybutane~
ExamPle 6~
In this Example the process was carried out using the ~ppaxatus of Fig. 3.
~ he first hydrolysis reactor was mad~ of stainless ~teel SUS 304 with an inner diameter of 2.5 m and a length o~ 10 m and packed with 30 m3 ~K lB H type cation exchange resi~. ~o the reactor were supplied liquid diacetoxybutane having the following composition, the circulating li~uid `~
from ~he second acetic acid separatox and feed water -containi~g 17.4% b~ weight of ace~ic acid at a rate of 4151 k~/hr, 3866 kgJhr and 355 kg/hr, respectively, at 60C under 2 kg/cm2G:
1~4-diacetoxybutane 87.7% (by weight) 1~2-diacetoxybutane 8.4%
l-hydrox~-2-acetoxybutane 3.9/0 ~rom the reactor~ a resid~ having the followi~g composition was removed at a rate of 8372 kg/hr.
H20 27.~./o (b~ weight) acetic acid 33.8%
1,4-diacetoxybutane 12.4%
l-hydroxy-4-acetoxybutane 16~/o 1,4-butanediol 4~/0 * Trade Mark :
i~
. ",, ,~, ~6)77S23 .

1,2 diaceto~ybutane 1.9% ' .
otherq 3.3%
~ he residue was supplied to the ~irst acetic acid separation column which was made of stainless steel SUS 316 with an in~er diameter of 2 m ~d a length o~
5 m and co~taining 10 valve trays and o]perated at a bottom temperature of 190C., u~der a head pressure of 100 Torr. and at a reflu~ ratio of 0.1 to obtain a residue co~taini~g 55.4% by weight of acetic acid a-t a 10 rate of 5109 kg/hr. ~he residue was s~pplied to the wate~-ac.etic acid separation column which w~s made of stainless steel SUS 316 with an inner diameters of 2900 mm at recovery zone and 2000 mm at concentratio~
zone and a length of 34 m and containing 64 perforated plates and operated at a bottom temperature of 125C, under a head pressure of 400 Torr. a~d a~ a reflux ratio o~ 570 and 7 simultaneously, the recovered acetic acid (~he co~centration being 95.8% by weight) from the acetoxylation stage was supplied at a rate of 18172 kg~hr.
RecoYered from the separatio~ column were a low boiling fraction co~taining tetrahydro~uran at the top and an aqueous fraction contai~ing 3.2% by weight of acetic acid at the 20th tray from the top a~ a ~ide stream at a rate of 10 kg/hr and 2880 kg/hr, respectively.
The residue of the first acetic acid separation column (3264 kg/hr~, the side stream of the water-acetic acid separation column (2880 kg/hr) and the side stream of the unreacted raw material recovery column (7223 kg/hr) were supplied to the second h~drolysis reactor which was :~ 30 similar to and operated under the same conditions as for - 22 - ;

the first reactor.
The hydrol~sis product havi~g the ~ollowi~g composition from the seco~d reactor was ~upplied at a rate of 13365 kg/hr to the second acetic acid separation column the size and the operation conditio~s of which were the same as those of the first sep~ration column:
H20 17. 7% (by weight) . acetic acid 11.2%
1,4-diacetox~buta~e 13.1%
1-hydrox~-4-acetoxybutane 34.~/o 1,4-butanediol 19.~/o 1,2-diacetoxybutane 0.8%
others 3.3%
~he overhead containing 38.9% by weight of acetic acid from the seco~d separation column was recirculated to the first reactor at a rate of ~866 kg/hr. Wkile the residue was supplied to the unreacted raw material recovery column which was made of stainless steel SUS 3Q4 with a~
i~ner di~meter o~ 2900 mm and a length of 25 m ana con-~0 taini~g 60 valve tray~ and operated at a bottom temperatureo~ 190C, undar a head pressure of 77 Torr. and at a reflux ratio of 80 ~nd, simultaneously, the overhead of the rectifyi~g column was supplied at a rate of 53 kg/hr.
Recovered from the recovery column were an sverhead containi~g 1,2-isomers~ mai~ly 1,2-diacetoxybutane~ at a rate of 393 kg/hr, a side stream at the 15th tray from the top containing 1,4-diaceto~ybutane, 1-hydroxy-4-acetoxybutane .~nd 1,4-buta~ediol at a rate of 7223 kg/hr, said side stream being recirculated to the second reactor, and a residue of the 1,4-butanediol product (purity being - 23 - .

~077523 .
99% by weight) at a r~te of 1936 kg/hr.
~ he residue was supplied to the rectifying oolumn which was made of ætainless steel SUS 304 with an inner diameter of 1700 mm and a length of 17 m and having 21 val~e trays ~nd operated at a bottom temperature of 190C, u~der a head pressure of 100 Torr. and at a ~ reflux ratio of 40. Recovered from the rectifying - column were a side stream of the 1,4-buta ediol pro~uct at the 4th tray from the top, an overhead containing tetra4ydrofuran and a æmall amount of 1,4-butanediol and a residue containing high boiling materials and a small amount of 1,4-butanediol at a rate of 1775 kg/hr, 53 kg/hr, and 55 kg/hr, respectivel~.

, . .

.

Claims (10)

The embodiments of the invention in which an exclusive property of privilege are claimed are defined as follows:

1. A process for producing butanediol or butenediol comprising contacting a mixture containing water and diacetoxybutane or diacetoxybutene with a solid acid catalyst bed to effect hydrolysis, the improvement wherein a portion of the hydrolysis product from which water and acetic acid have simultaneously been removed is mixed with said water and said raw material acetic diester to form a uniform aqueous solution which is then supplied to said bed.

2. A process according to Claim 1, wherein the hydrolysis product from which acetic acid and water have simultaneously been removed is subjected to azeotropic distillation to obtain the minimum-boiling or a diol-rich mixture containing acetic diester, monohydroxyacetic ester and diol and said azeotropic mixture is mixed with water and acetic diester to form a uniform aqueous solution which is then supplied to said bed.

3. A process according to Claim 1, wherein said diacetoxybutane is 1,4-diacetoxybutane.

4. A process according to Claim 1, wherein the proportion of the hydrolysis product to be mixed is from 0.5 to 10 times by weight that of the sum of the raw material diacetoxybutane or diacetoxybutene and water.

5. A process according to Claim 1, wherein the proportion of said hydrolysis product to be mixed is from 1 to 3 times by weight that of the sum of said raw material diacetoxybutane or diacetoxybutene and water.

6. A process according to Claim 2, wherein the proportion of said azeotropic mixture to be mixed is from 0.05 to 10 times by weight that of the sum of said raw material diacetoxybutane or diacetoxybutene and water.

7. A process according to Claim 2, wherein the proportion of said azeotropic mixture to be mixed is from 0.1 to 1 time by weight that of the sum of said raw material diacetoxybutane or diacetoxybutene and water.

8. A process according to Claim 2, wherein said azeotropic distillation is effected in a distillation column at a bottom temperature of from 150 to 200°C, under a head pressure of from 10 to 200 mmHg and at a reflux ratio of from 1 to 10.

9. A process for producing 1,4-butanediol comprising contacting in two reaction vessels characterized by the steps of:
(a) continuously supplying 1,4-diacetoxybutene, water and an overhead from a second acetic acid distillation column to a first hydrolysis reactor to effect catalytic reaction, (b) supplying the liquid reaction product to a first acetic acid distillation column to distill off a water-acetic acid fraction, (c) separating water from said fraction in a water-acetic acid separation column, (d) supplying the residue obtained from the first acetic acid distillation column in the step (b), the water obtained from the step (c) and the recirculating liquid obtained from the step (f) to a second hydrolysis reactor to effect catalytic reaction, (e) supplying the resulting liquid reaction product to a second acetic acid distillation column to obtain an overhead of water-acetic acid fraction which is recirculated to the step (a), (f) supplying the residue obtained from the second acetic acid distillation column to an unreacted raw material recovery column to recover unreacted diacetoxybutane and a monohydroxy-monoacetoxybutene-containing fraction, the latter being recirculated to the step (d), and (g) recovering the residue containing mainly 1,4-butanediol.

10. A process according to Claim 9, wherein the raw material 1,4-diacetoxybutane contains 1,3- and 1,2-isomers and, 1,2-isomers is distilled out while a side stream containing mainly unreacted diacetoxybutane and monohydroxyacetoxybutane is recovered and recirculated to the step (d).