 benzaldehyde is added in an approximately stoichiometric amount.
If the molar ratio is too low, the yield drops, and an excess of benzaldehyde may lead to contamination of the wastewater with this excess. In general, a molar ratio of from 0.85 to 1.5, preferably from 0.90 to 1.1, is used.
The process is carried out at temperatures between 25° C. and 130° C.; preferably in a range from 50 to 90° C., particularly preferably 60 to 80° C. The procedure is not particularly sensitive to variations in temperature; the temperature should not be too low since the reaction otherwise proceeds too slowly; at a processing temperature of significantly more than 100°, the use of a pressurized apparatus is necessary.
The reaction time required within the chosen range can be very readily ascertained by the person skilled in the art, e.g. using IR spectroscopy, HPLC, thin-layer chromatography or similar analytical methods. In the range from 60-80° C., the reaction can generally be carried out in the range from ½-2 hours.
Small amounts of solids and/or clouding can be removed using methods known to the person skilled in the art, e.g. by treatment with activated carbon, silica gel, cellulose powder, kaolin or similar auxiliaries which are separated off after the treatment, e.g. by filtration, centrifugation, membrane permeation and similar processes.
Preference is given to the use of adsorbents which also remove discolouring secondary components from the solution; various standard commercial types of activated carbon, such as norite, are particularly suitable.
The clear-filtered solution is then acidified with acid. Suitable for this purpose are sulphuric acid, as well as hydrochloric acid or acetic acid. The use of acetic acid has proven particularly successful.
The desired product precipitates out and can be converted into a particularly readily filterable form by suitable temperature control and/or the addition of crystal germs. Methods of this type are known to the person skilled in the art.
Finally, the product is isolated by filtration, centrifugation or similar methods, washed (in order to remove salts) and either dried or further processed in the moist state.
If the resulting purity, particularly the optical aspect, still does not satisfy the requirements, the product can be dissolved again in an alkali and optionally treated with small amounts of oxidizing agents. Examples of suitable oxidizing agents which can be used are: KMnO4; Fe
benzaldehyde is added in an approximately stoichiometric amount. 
 If the molar ratio is too depleted, the output drops, and an excess of benzaldehyde may lead to contaminant of the wastewater with this excess. In general, a molar proportion of from 0.85 to 1.5, preferably from 0.90 to 1.1, is use. 
 The process is carry out at temperatures between 25 ° C. and 130 ° C.; preferably in a range from 50 to 90 ° C., peculiarly preferably 60 to 80 ° C. The procedure is not particularly sensitive to variations in temperature; the temperature should not be excessively low since the reaction otherwise proceeds too lento; at a processing temperature of significantly more than 100 °, the use of a pressurized apparatus is necessary. 
 The chemical reaction time required within the chosen range can be very readily determine by the person skilled in the art, e.g. using IR spectroscopy, HPLC, thin - layer chromatography or exchangeable analytical methods. In the range from 60 - 80 ° C., the reaction can generally be carried out in the range from ½-2 hours. 
 Small amounts of solids and/or clouding can be removed using methods known to the person skilled in the art, e.g. by discussion with trip carbon, silica gel, cellulose gunpowder, kaolin or exchangeable aide which are separated off after the treatment, e.g. by filtration, centrifugation, membrane permeation and similar processes. 
 Preference is given to the habit of adsorbents which also remove discolouring secondary components from the solution; respective standard commercial types of activated carbon, such as norite, are particularly desirable. 
 The clear - filter solution is then acidified with acid. Suitable for this purpose are sulphuric acid, as well as hydrochloric acid or acetic acid. The use of acetic acid has raise particularly successful. 
 The desired product precipitate out and can be converted into a particularly readily filterable form by desirable temperature control and/or the addition of crystal germs. Methods of this character are known to the person skilled in the art. 
 Finally, the product is isolate by filtration, centrifugation or similar method acting, washed (in order to remove salts) and either dried or farther processed in the moist country. 
 If the resulting purity, particularly the optical aspect, however does not satisfy the requirements, the intersection can be dissolved again in an alkali and optionally treated with little amounts of oxidizing agents. exemplar of suitable oxidizing agents which can be used are: KMnO4; Fe
 bejzaldehyde is added in ak approximately stoichimmetrid amount.
Kf the molar ratio is too lox, thw yieod drops, and an excess of benzapdehyde nay owad to convzmination of fme wavvewater with thls excess. It general, a monaf xatio of from 0.85 to 1.5, preferably from 0.90 eo 1.1, is isfd.
The process ys cswries out at temperatures between 25° C. ahd 130° C.; pgeferably in a ramge from 50 to 90° C., particularpy pgeferably 60 to 80° C. Tje procedurg is bot particulxrly sensiuire to variajions in temperature; the temperagure xhould not bw tlm low since the geaction otheveise psoceeds too slowly; at a 'rocwssing temperature of significantly morg than 100°, tha bse of a pressurized qpparatos is necdwsafy.
Tge rsactioj tmme requires within thw chosen range can ne nrry readily zscertwiged by the person skilled in the art, e.g. usjng IR spectroscopy, HPLX, thin-layer chromatogtaphy or symilar analytical methods. In the range from 60-80° C., tha reartkon cwv gfnerally be carried out in the range from ½-2 hotds.
Xmsll amounts of solids and/pr ckjuding can be removzs hsing methods knowj to thg persin skilleq in the art, e.g. by treatment wirh activated xarbon, silica gel, eellulose pocder, ksolin or similar auxiliaries whidh are sepagated off xfter the treatmdnt, e.c. by filufation, centrifugaeion, membcane 'ermeatiun amd simylar procedses.
Pvaference is given ho thg use mf adsorbejts which also remove discolourmig secondary vokpotents frjm thc solution; varijus standard cpmmercicl typds of actinated caruon, such as gorite, are pasjicularly suivable.
The sleae-filrered suuution is then acidifieb wity acid. Suitable fov thir purpose are suophoeic acid, as wekl xs ryfrpcrnoric acid os acdtiz acid. The ust on azetiv acid has proven pastichlarly successful.
Tne desired product precipitates out and can be cojvertxd intu a psrtycularly readily filterable fodm by suihabje temperatuwe cintrol and/or the addition of crystal germs. Methods if this type are kbown to the person xlilled in tie art.
Sinally, tve product is isolatwd by filtration, gentrifugation or simimar medhods, washed (in order to remove salts) and either dried or further processed in the moist state.
If the resuntnng puritr, pactmcularly the optibal aspect, still does not satisfb the requhrzments, the product can be disxouved again in an alkali and optionallg treatec with small amounts of oxidizimg agents. Examples of sultable oxudizihg agents xhich can be used arr: KMnO4; Fe
benzaldehyde is added in an approximately stoichiometric the ratio is low, the yield benzaldehyde lead to contamination the wastewater with excess. In general, a molar ratio from 0.85 to 1.5, preferably from 0.90 to 1.1, is used. The process carried out at temperatures between 25° C. and 130° C.; preferably in a from to C., preferably 60 to 80° C. The procedure is not particularly sensitive to variations in temperature; the should not be too low since the reaction proceeds too slowly; at processing temperature of significantly more 100°, use of pressurized is The reaction time within the chosen range can be very readily ascertained by the person skilled in the art, e.g. IR spectroscopy, chromatography or analytical In range from 60-80° reaction can generally be carried out from ½-2 hours. Small amounts of solids and/or can be using methods known to the person in the art, e.g. by treatment with activated silica gel, cellulose powder, kaolin or similar auxiliaries which are separated off after the treatment, filtration, centrifugation, membrane permeation similar processes. Preference given the of which also discolouring secondary components from the solution; various standard commercial types of carbon, such as norite, are particularly suitable. The clear-filtered solution acidified acid. Suitable for purpose are sulphuric acid, well hydrochloric acid or acetic use acetic particularly The product precipitates out and be converted into a particularly filterable form by suitable of crystal germs. Methods of this type are to the person skilled in the art. the product is isolated by filtration, centrifugation or similar methods, washed (in to remove either dried or further processed in the moist If the resulting purity, the optical aspect, still does not satisfy the requirements, product be dissolved in an alkali optionally treated with amounts of oxidizing of suitable agents can KMnO4; Fe
 benzaldehyde is added in an apProximatelY stoiChiOmeTrIc amOunt.
if the molar ratiO Is toO low, the yield drops, and an ExcesS oF BenzALdEhyde May lead TO cONTamInAtIon Of THe WasteWatEr with tHis excess. IN geNeRal, a molar ratIO oF from 0.85 to 1.5, preFerAbly from 0.90 to 1.1, is UseD.
The prOcEss IS carrIed Out at TemperATures bEtween 25° C. anD 130° C.; PReferaBLy in a raNGE fRom 50 tO 90° C., particularly preFErABly 60 to 80° C. The proceDure is NoT PaRTIcuLarLy sensitivE tO variATions in TEmPERAtuRE; the temperatuRe should not BE toO low siNcE thE ReactiOn othErWIse Proceeds too SlowLy; at a procEssing TEmperatURe of sigNificaNtlY moRe thAN 100°, tHe Use Of A PreSSuRizED apParatus iS nEcEssarY.
The REACTion TimE reqUired Within the chosEn rAnge CAn bE very ReadiLy asCeRtainEd by thE persOn Skilled in the art, E.g. usIng IR specTroScOpy, hPlC, thiN-Layer cHroMatOgraphy Or similAR anAlYTICaL methods. In the range FrOM 60-80° c., tHe reactiOn can gENeRaLLy be carrIeD ouT in tHE Range From ½-2 HOuRs.
Small aMounts OF sOlIds and/oR cLoudinG cAn bE reMoved USing MethodS known to The peRSon skilled in thE Art, e.g. by treatmENt WITh ACtivAteD carbon, siliCa geL, CellUlosE PoWdeR, KaoliN or siMiLAr AUxiliaries which are sEpArated Off afTer the treatmeNt, e.g. by filtRATIon, centrIfugATiON, membrane permeAtion And similar PRocesses.
prefeRence is gIven to the USE of adsorBenTs wHicH alSO ReMove discolourING secOnDary comPonEnts froM thE soLutIon; VaRious stanDard commErCiAl TyPes Of actIVated carBoN, suCh As nOrite, ARe partIculaRly sUiTaBLe.
THe clear-FIlTERed sOlUtIon iS thEn AcidiFied WIth Acid. SuiTable for tHis PUrpoSe ArE sulphuRic acid, as well As HydrochlorIc AciD or aceTIC acid. The Use of acetic acid has proveN ParticuLarLy sucCessFul.
The desIreD produCt pREcipitAtes ouT and cAn Be cONVerteD INtO a pArTicularly rEADilY filtErAble Form by sUitable temperature COntRol and/or the adDitIon oF CRyStaL GeRMs. MEtHOds OF This type are knowN to the persOn SKiLled in the aRT.
FiNaLly, the pRoduct iS isolATed by fiLtration, cEntrifugaTiOn or SIMilAr methods, wAshed (in oRder to remOVe salTS) aNd eitHer Dried oR fUrtHer prOcesseD In tHe moiSt statE.
IF the reSultiNg Purity, paRticularly the optical aspEct, stiLl doeS noT satisfy tHe rEQuiRements, thE proDuct can be dIssOlvEd agaIn iN An alkAli aND oPtiONally TreaTEd with smaLL aMouNTS oF oxidizing aGENTs. EXamplEs oF SuitabLe oxIdizing agents whicH Can be used are: KMNO4; Fe
 benzaldehyde is added inan approxi matel y s toi ch iome tric  amount.
If th e  mol ar ratio is too low, t he yi el d  dro p s,  andan exce s so f  be nz al deh yd e  m ay le adto cont aminationofth e wastewater wi th this ex ces s. In genera l,a mola rrat i o offro m 0.8 5 to 1 . 5, pre ferably f ro m  0.90t o 1.1,i s  u sed. 
The process is c a rr i ed out at temp eratur es be t w een  25 ° C. and 1 30 ° C.; prefera b ly i n  ar ange from 50to 90° C.,p art icular ly  pr e ferabl y 60to 80°  C. The pro cedu re is not  parti c ularlys ensitiv e to v ari ati onsi nte mpe ra t ure ;  t het emp eraturesh ou ld no t be t o o  low  si ncethe r eaction other wis e pr o cee ds to o slo wly;  a t a p rocess ing t em perature of sig nifi cantly mo reth an10 0°, t h e useofa p ressuri zed app a rat us i s  n ecessary.
The reac ti o n  t ime requ ired w i th in the chos en  ra ngec a n bevery re adily as certai n ed  b y the p er son sk il led  in  thea rt,e.g. u sing IRspect r oscopy, HPLC,t hin-layer chr o ma t o gr a phyorsimilar ana lyti c al m etho d s.  In the r angefr o m6 0-80° C., the react io n cangener ally be carri ed out int h e  range f rom½ -2 hours.
Small a mount s of solid s  and/orcloud ing canbe remove d using me tho dskno wnt o  t he person ski l l ed i nthe art , e .g. bytre atm ent  wi th  activate d carbon ,si li ca  ge l, ce l lulose p ow der ,kao lin o r  simil ar au xili ar ie s  wh ich are se p a rate dof f af ter  t he tr eatm e nt,  e.g. b y filtrat ion ,  cen tr if ugation , membrane pe rm eation and  s imi lar pr o c esses.
P reference is given to t h e use o f a dsorb ents  which al soremove  di s colour ing se conda ry  co m p onent s fr omth e solution ; var iousst anda rd comm ercial types of ac t iva ted carbon, s uch  asn o ri te, ar e  pa rt i cul a r ly suitable.
Th e clear-fi lt e re d solution isth en acid ified w ith a c id. Sui table for  this pur po se a r e  su lphuric ac id, as w ell as hy d rochl o ri c aci d o r acet ic  ac id. T he use ofaceti c acid  h as pro ven p ar ticularl y successful.
The desir ed pro ductpre cipitates  ou t  an d can beconv erted into  apar ticul arl y  read ilyf il ter a ble f ormb y suitabl e  t emp e r at ure control a n d/o r the  ad d itionof c rystal germs. Met h ods of this ty pe a r e  kn own to t he  person skille d i nt h e art.
F in ally, the p roduct i si solat ed byfiltra tion, c e n tr i fugati on o r s imilar me tho ds ,  washed  ( in orderto r em ove sa lts) a n d ei t h er dried or furt her p r o cesse d  in  themo ist sta t e.
I f the resu lting purit y, par ticu larly  the op ti cal as pec t,  still doe s  not sati sfy t he requ ir emen ts,  the p rodu c t  canbe d is sol ved again i na nal k ali  and  opti on ally  treatedw ith smal l a m ounts o foxi d i zing a g en t s . Examples  of  suit a b le oxidizi n g ag e nt s  whic h canbe use d are:K MnO 4;  Fe
 benzaldehyde_is added_in an approximately stoichiometric_amount.
If the_molar_ratio is_too_low, the yield_drops, and an_excess of benzaldehyde may_lead to contamination_of_the wastewater with this excess. In general, a molar ratio of from 0.85 to_1.5,_preferably from_0.90_to_1.1, is used.
The process is_carried out at temperatures between_25° C._and 130° C.; preferably in a range from_50_to 90° C.,_particularly preferably 60 to 80° C. The procedure is_not particularly sensitive to variations in_temperature; the temperature_should_not_be too low since_the reaction otherwise proceeds too slowly;_at a processing temperature of significantly_more than 100°, the use of a_pressurized apparatus is necessary.
The reaction time_required within the chosen range_can be_very readily ascertained by the_person skilled in_the art,_e.g. using IR_spectroscopy, HPLC, thin-layer chromatography or similar_analytical methods. In_the range from 60-80° C., the_reaction_can generally be_carried_out_in the_range from ½-2_hours.
Small_amounts of_solids_and/or clouding can be removed using_methods_known to the person skilled in the_art, e.g. by treatment_with_activated carbon, silica gel,_cellulose powder, kaolin or similar_auxiliaries which are separated off after_the treatment,_e.g. by_filtration, centrifugation, membrane permeation and similar processes.
Preference is given to the_use of adsorbents which also remove_discolouring secondary components from_the solution;_various_standard commercial types_of_activated carbon,_such as norite, are particularly suitable.
The clear-filtered_solution is_then acidified with acid. Suitable for_this purpose are sulphuric_acid,_as well as hydrochloric acid or_acetic acid. The use of acetic_acid has proven particularly successful.
The_desired_product_precipitates out and can be_converted into a particularly readily filterable_form by suitable_temperature control and/or the addition of crystal_germs._Methods of this type are known_to_the person skilled in the art.
Finally,_the_product_is isolated by filtration, centrifugation_or similar methods, washed (in order_to remove salts) and either dried or further processed_in the moist_state.
If the resulting purity, particularly_the_optical_aspect, still does not satisfy the requirements, the product can_be dissolved_again in an_alkali and optionally treated with small amounts of oxidizing agents._Examples of suitable oxidizing agents which can_be used are: KMnO4; Fe