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Patented Sept. 3, 1946 ’ 2,406,972 PROCESSES FOR PRODUCTION’QEPQY-RIDINE‘ ‘ 3-SULPHONIG ACID AND‘lI-TS SAIiTS’f Edmond'Ti'?Tiszajand‘Bernard F. Duesel, Yonkers, NE SE, assi-gnors -‘ to Pyridium Corporation, Yonkers; NJ Y1, incorporation of New York No; Drawings ‘Application’. February- 24>, 194%} ' ’ Seri'al‘lNo. 4763908? 40mins; ‘ (01. 260-290i 1;‘ > 'Our invention relates to improvements‘ in; the‘. process of sulphonating, pyridine andrefers' par= ticul-arlyin processes‘ for obtaining pyridine 3 sulphoni‘eiacid and its salts. The 'sulphonationl of. pyridine takestplacez acaw cordingitoithexfollowingiormula; ‘ While the sulphonation of‘many aromatic com pounds‘of" the benzene series is easily) accom pli‘sh'e'd“ by treating them with concentrated’ sull phuric acid‘ or‘ oleum at'relatively low tempera tures,‘ the yield, being almost quantitative; pyri; dine‘ and" its derivatives offer considerable resist ance' to sulphonation" by the processes adapted forv the. sulphonation‘ of‘ members of‘ the benzenev series: ' r ‘ It; is- 1 evident- ‘from this» equation :-that peachsmolj of ‘ pyridine? (in; wt? 79'), liberates; one; mola oii wa-t ter-MB) duringsulphonationt I We ‘have-found that .thissliberatedtwater-z dilutes? the ‘ sulphuric < acid to such‘ amextentt as ; to s-ma-ke, itttooaweak for the“sulphonationttoany consid ‘ Numerous attempts have been made to over come" the" dif?culties present‘: in the sulphonation erable -' degree- and that the presence of‘. a; dehy-e drating; agent.‘ in su?icient; quantity» to‘ take. up : the-i water: results. in; increased; yieldst ideal,» dehydrating: agent-for. thistpurpose is fuming sul-.-~ of ‘ pyridine‘, but they have all'resulted'ih the use of‘ex'cessive amounts of‘the: sulphonating‘ com pound; prolonged'heatingat highly elevatedlteni perature's' and of‘ comparatively small‘ yields.‘ The following'are amongithe previous ‘attempts to sulphonate pyridine: phuric'; acid, it the‘ S03 —- oi?‘ which; forms- sulphuric. acid With‘the water.“ Using an oleumicontaining~v 20%;- S03; ?ve-parts areirequired‘. theoretically to take care of the producediwater.‘ > One process consisted‘ in heating the‘ pyridine It must, be considered, however; that-‘when; pyw with excessive proportions of’sulphuric acid and‘ ridinehis? added- to the,» oleum,. some, 0t the-S93; Yes? sulphuric anhydride" at 3I3‘O°'-’-350°“ C. for‘ sixty‘ capes from: the:oleum duringgthea' heating: oil the‘: hours; the-sulphuric acid which was distilled'off" 25 sulphonating process, and, hence; increased yields! at these" high temperatures" being replaced from" are‘ obtained by; employingT an- . amount 4 in‘. excess”. time to time: In addition tothe large amounts of‘ the sulphonating chemicals; and‘ the’ l'engthrof’ o?thetheoreticatquantityt time employed, the yieldswere‘verysmall. We have now found, that we=cantincreaseithea yield’ of pyridine 3-sulphonic acid considerably Attempts“ have been made“ to‘ produce the'sul- 30 by adding oleum tethereaction mixture at in phonati'on» by ‘heating pyridine withconcentrated“ tervals. We; have: ‘found; also that it: isiadvisable to: :add': a;.f.urther."smalhquantity 0ft: catalyst with“: sulphuric‘ acid sealed‘ tubes‘ to the' boiling‘point“ of‘ the- mixture; 320°'-330°‘ 0., for" thirty >' or"i"orty* hours without‘ satisfactory results? Further attempts have been madeby‘ adding a: catalyst, mercurysulpha-te; vanadiumsul‘phate, aluminum‘ sulphate‘ or. magnesium sulphate; to" the" pyridine; sulphuric a-cid‘and' sulphuric" anhy dfi‘i-de; heating’ to 330°'-350°" C, for'forty to‘ sixty‘ hours‘ and‘replacing" the distilled sulphuric acid“ with additional amounts of'the acid; Whileth'is" process increased the" yield‘ above“ that" obtained‘ eachsa-dditiorr OfZEOlGlll'l'lL. ‘ With. periodical: additi'onsz'oflf oleuma and? proper? 35 catalysts‘i‘ we‘ have: practically" doubled-L the‘ yield} of: pyridine 3:-sulphoni'ci aci'dc. ‘compared: with‘; yields obtainedrby =the§previonsly< described meth'-_ O'd‘S‘L- For:instance;.: using: mercury‘or its-salts~ as; catalysts, the. yield‘ i‘s137'%, our>yie1dris:»abouti 75% ;: using: magnesiumz. as scatalystltby i the usual?‘ method; the; yield: is: 14%,‘- by" our method‘: the: . yieldi isaw about. 23%;‘ usings aluminum; _ catalyst"; in‘ the- absence of‘ the catalyst; it“ still possessed" by the usual method, the yield isA12i%l,‘ ounfyield: is about 22%. gards". the : amounts ‘of 'sulphonatingmaterials"em; 4.7151? An object‘ of this invention, therefore,.. is to the" disadvantages of“ the‘ former‘ " processes" ployed. re‘; increase the? yield’. of pyridine 3.-sul’p'honi‘c‘ acid,‘ ’ Our invention presents. processes for the pro-‘ while: at" the‘ same .timeureducingj the'xamountfof” duction ofipyridine3¢su1phonic acid in which the the‘ sulp‘honating agent‘ and‘ijthe‘ time‘ of‘ opera- _ amountofchemicals and‘ the time of procedure tion'. ‘ are materially decreased, and the yield is con 50 Another object is to prevent the undue dilu siderably increased over those of the described tion of the sulphonating agent by the periodical processes, these advantageous results being ob addition of a dehydrating agent. tained by the particular steps of procedure of our Further objects of this invention will be evi processes which are not present in the prior proc esses. ' dent from the herein described processes and .55 the results produced thereby. 2,406,972 3 ~ Among the catalysts suitable for application in our processes are mercury, aluminum, magnesi um and vanadium and their salts, but we do not limit ourselves to these catalytic metals, as other suitable catalytic metals may be employed. These catalysts dissolve in the hot sulphuric acid as the corresponding sulphates, and therefore, the sulphates may be added to the sulphonating _ 4 310°-320° C. After heating for one hour, 0.5 part aluminum and 16 parts oleum are added. This is repeated after the second and third hour of heating, and then the heating is continued for eight more hours. The sulphonation mixture is then cooled and added to water and worked up for the sodium salt in the usual way.‘:1 -12'.7 parts of sodium salt was obtained representing a yield ' of 21.6%. mixture. Example IV Our preferred method of sulphonation can be 10 clearly seen from the following illustrative ex A pyridinium sulphate solution in 75 parts of amples. All parts referred to in these examples oleum is prepared from 25 parts pyridine as de are given by weights. scribed in Example I. Two parts of mercury sulphate are added to the solution and heated to Example I ' 15 270° C. After an hour heating 16 parts of oleum 250 parts of pyridine are run as a ?ne stream into 750 parts of oleum (fuming sulphuric acid, 20% S03) under stirring and cooling, taking care that the temperature does not rise over 75° C. The mixture now consists of a solution of pyri dinium sulphate in oleum. Three parts of mere cury are added to the solutionv and heated to about 250°-270° C. under constant stirring. After an hour heating 160 parts of oleum and 1.5 parts of mercury are added. vThe heating is con tinued, and after the second and third hour heating, each time the same amount of mercury and oleum is added thereto. The heating is then continued for two more hours and then cooled down to room temperature. p and 1 part of mercury sulphate are added. The heating is continued, and the addition is repeat ed after an hour of heating. The heating is then continued and the reaction mixture is worked up as in Example I. The yield obtained is 68% of the theoretical. , _ It will be noted from the foregoing that our invention broadly comprises the periodical addi tion ofoleum and a catalyst to a mixture of pyridinium, oleum and a catalyst, whereby in creased yields are obtained over former processes, with decreased amounts of materials and at lower temperatures. As already mentioned other metals than those The mixture is now 30 described in the examples, may be used as cata added to 7500 parts of Water and neutralized with ?nely pulverized calcium carbonate. ‘ The calcium sulphate formed is ?ltered off and washed with hot water. ‘The ?ltrate now con tains calcium 3-pyridine sulphonate and the un reacted pyridine, which pyridine may be recov ered.v Sodium or potassium carbonate is now added to the solution till it becomes alkaline to lyst in the sulphonation of pyridine without de parting from the invention or sacri?cing the ad vantages thereof. Therefore, we do not limit ourselves to the speci?cally mentioned times, temperatures, quantities, chemicals, or steps of procedure as these are given simply to describe our invention as set forth in our speci?cation and claims, and they may be varied without going phenolphthalein, the calcium carbonate is ?l . beyond the scope of our invention. tered off and the solution is evaporated to dry 40 What we claim is: ness. By using 130'parts of sodium carbonate, 1. In a process of sulphonating pyridine in the 442 parts of sodium 3-pyridine sulphonate is ob 3 position, the step which comprises the periodi tained which represents 77% yield. If the free S-pyridine sulphonic acid is required, the cal cal additions of oleum and a member of the group of catalysts consisting of mercury, aluminum, magnesium and vanadium and their sulphates cium is removed from the calcium salt by the 45 addition of the theoretical amount of sulphuric to a solution of pyridine sulphate in oleum under acid, the calcium sulphate is ?ltered off, and the sulphonating temperatures and recovering the solution is evaporated to dryness. 3 pyridine sulphonic acid. Example II 2. In a process of sulphonating pyridine in the 50 3 position, the step which comprises the periodi A pyridinium. sulphate solution in 50 parts cal additions of oleum and mercury to alsolution oleum is prepared from 25 parts of pyridine as of pyridine sulphate in oleum at temperatures described in Example I. 1.5 parts of magnesium between 250°—320° C. and recovering the 3 pyri turnings are added to the solution and heated to 270°—300° C. After heating for one hour, 0.375 , dine sulphonic acid. 3. In a process of sulphonating pyridine in the part of magnesium and 16 parts oleum are added. 3 position, the step which comprises the periodi This is repeated after the second and third hour cal additions of oleum and magnesium to a solu of heating, and then the heating is continued tion of pyridine sulphate in oleum at tempera for nine more hours.‘ The sulphonation mixture is then cooled and added to water and worked 60 tures between 250°—320° C. and recovering the 3 pyridine sulphonic acid. _up for the sodium salt in the usual way. 13.5 4. In a process of sulphonating pyridine in the parts of sodium salt were obtained, representin 3v position, the step which comprises the periodlé ~ cal addition of oleum and mercury sulphate to a Example III solution of pyridine sulphate in oleum at temper A pyridinium sulphate solution in 75 parts 65 atures between 250°-320° C. and recovering the 3 oleum is prepared from 25 parts pyridine as de-, pyridine sulphonic acid. EDMOND T. TISZA. a yield of 23.5%. scribed in Example I. 1.5 parts aluminum turn-v ings are added to the solution and heated to BERNARD F. DUESEL.