alexander j. fatiadi et al- cyclic polyhydroxy ketones. i. oxidation products of hexahydroxybenzene...

8/3/2019 Alexander J. Fatiadi et al- Cyclic Polyhydroxy Ketones. I. Oxidation Products of Hexahydroxybenzene (Benzenehexol)

1/10

JOURNAL OF RESEARCH o f t h e Nat io n a l Bu reau o f S t an d ard sA. Ph y s i cs an d Ch em is t ryVo l . 6 7 A, No . 2 , March -Ap r i l 1 9 6 3

Cycl ic Polyhydroxy Ketones . I . Oxidat ion Products ofH ex ah y d ro x y b en zen e (Ben zen eh ex o l )Alexander J. Fatiadi, Horace S. Isbell, and William F. Sager*

(De cem b er 1 1 , 1 9 6 2)

R e l i a b l e p r o c e d u r e s a r e g i v e n f o r t h e p r e p a r a t i o n a n d p u r i f i c a t i o n o f h e x a h y d r o x y b e n z e n e ( b e n z e n e h e x o l ) , t e t r a h y d r o x y - p - b e n z o q u i n o n e , r h o d i z o n i c a c i d , t r i q u i n o y l ( c y c l o -h e x a n e h e x o n e ) , c r o c o n i c a c i d , a n d l e u c o n i c a c i d ( c y c l o p e n t a n e p e n t o n e ) . C e r t a i n d e r i v a t i v e san d co lor t es t s , a s wel l a s i n f r a re d an d u l t r av io l e t sp ec t r a , a r e r ep o r t e d fo r t h e i r i d en t i f i ca t i o n .

1. IntroductionOn oxidat ion, cyclohexanehexols ( inosi tols) yield

[1 -5 ] . l In progressing from cyclo-

H O -I I O -

, - O HO H

Hexahydroxybenzene(Benzenehexol)

YI ITetrahydroxy-p-benzoquinone

O0 = fO

O H

=0=0

6IV

Triquinoyl (Cyclohexanehexone)O

0= '

V ILeuconic acid(Cyclopentanepentone)

* The George Washington Univers i ty, Washington, D. C.1 Figures in brackets indicate the literature references at the end of this paper.

Hexahydroxybenzene (benzenehexol , I ) can beprepared from inosi tols (cyclohexanehexols) and fromte t rahydroxy-p-benzoquinone ( I I , ob ta ined by self-cond ensat ion of glyoxal in a lkal ine solut io n) . Oxidat ion of I yields II , which is fur ther oxidized torhodizonic acid (III) , and this is oxidized to t r i qu inoy l (cyc lohexanehexone, IV ) . Te t rah yd rox y-^ -benzoquinone and rhod izon ic ac id a re no t on lyinterest ing in their own r ight , but a lso serve asin te rmedia tes in the p repara t ion o f c roconic ac id(V), a dihy drox y t r ik eto ne hav ing a f ive-carbonring . Ox idatio n of crocon ic acid yields leuconicac id (VI) . Because these comp ounds , needed asmodel subs t ra tes in a s tudy of an t iox idan t andoxygen -carr ier p rope rt ies , we re no t a vai lable in asu i tab le s ta te o f pur i ty , the methods repor ted in theexperimental par t were developed for their synthesisand purif icat ion.2 . Hexahydroxybenzene (Benzenehexol, I) [7]

2 . 1 . DiscussionHexa hydro xyben zene ( I ) , the eno lic fo rm of th et r ihydroxyt r ike tocyc lohexanes , can be p repared bythe self-condensat ion of potassium carbonyl fol lowedby hy drolysis [8, 9] , by ni t ra t ion of d i-O-acetylh y-droquinone fo l lowed by reduc t ion and hydro lys i s[10], by oxidation of m?/o-inositol followed by enoliza t ion [11] , and by reduc t ion of t e t rah ydr oxy -p-benzoquinone ( I I ) by means o f s tannous ch lor ide

[12].2.2 Preparation of Hexahydroxybenzene [13] 2

Stannous chlor ide dihydrate (100 g, 0.44 mole) isadded in one port ion to a boi l ing, mechanical lyst i r red solut ion of 10 g (0.058 mole) of t e t r ah yd rox y-p-ben zoqu inon e (I I) in 200 ml of 2.5-N h y d r o chloric acid. In a few m inu tes , th e red color of I Idisappears and long, needle- l ike crystals of hexa-2 Th is procedu re was developed in 1959 by one of us (A J . F . ) , under the direction of Dr. W illiam F . Sager at George Washingto n U niversity [13], and w asbriefly described by Fieser and Fieser [14].

153


2/10

hydrox ybenze ne ( I) beg in to fo rm. Con cen t ra tedhydro chloric acid (250 m l; specific grav i ty 1 .08)is added, and the s t i r red suspension is heated tobo i l ing , mixed wi th 600 ml o f concen t ra ted hydrochloric acid, cooled in ice, and filtered with suctionon a fritted -glas s filter. As m uc h solv ent as pos s ible is removed by suct ion, without exposure toair , by covering the f i l ter with an inverted funneland in t rod uc ing n i t rogen , an d by us ing a po lye thy l ene dam to remove the f inal t races of the solvent .For purif icat ion, the crude product is dissolvedin 450 ml of hot 2 .5-iV hydro chloric acid con taining3 g of s tann ous ch loride d ihy dra te . Deco lor iz ingcarbon is added, the hot suspension is f i l tered, theinso lub le m at te r i s washed w i th 75 ml of ho t wate r ,and the combined f i l t ra te and washings are mixedwith 1 l i ter of con cen trate d hydro chloric acid andcooled in ice . Th e resu l t ing crystals are col lectedon a fritted -glas s filter, in an atm os ph ere of nitrog en ,washed with 100 ml of a cold, 1:1 mixture of ethanoland concen t ra ted hydroch lor ic ac id , and dr ied oversod ium hydrox ide in a vac uum des icca to r to g ive7 to 8 g (ab out 7 5% ) of color less crystals wh ichd o n o t m e l t 3 whe n placed on a ho t pla te a t 310 C.

In f ra red and u l t rav io le t absorp t ion spec t ra a re re corded on pages 158 and 160.Hex ahy drox yben zene can a lso be rec rys tal l izedf rom 2-methoxye thanol by the add i t ion o f benzene ;the c rys ta l s a re separa ted , washed wi th ace tone , anddried in a va cu um desicca tor . T he yield is abo utthe same as in the p rev ious method .Charac te r i s t i c der iva t ives o f hexahydroxybenzeneare th e hex aac etat e , m p 203 to 205 C [10, 15] , thehex abe nzo ate , m p 323 to 325 C [9], and th e hexa-methyl e ther , mp 81 C [16] .The fol lowing convenient color tes ts may be usedfor iden t i f i ca t ion o f hexahydroxybenzene :(a) (Dev eloped in this labo rato ry.) A solut ionof ferric c hlorid e in 1:1 aqueo us m eth an ol is slowlyadded dropwise to a s t i r red, aqueous solut ion ofhexahydroxybenzene under a s t ream of n i t rogen .As addition of the ferric chloride proceeds, the color ofthe solut ion passes successively through the fol lowingcharac te r i s t i c se r ies , r epresen t ing ox ida t ion s teps :ma gen ta o r cher ry red ( I I ) ; g reen ( I I I ) ; and , f inally,a s tab le , deep b lue (p resumably a mix ture o f I I I andI V ) . When the solut ion is cooled in ice for severalhours , color less crystals of the octahydrate of IVg r a d u a l l y s e p a r a t e .(b) [9] One ml of a con cen trate d, a que ous so lut ionof bar ium chlor ide is mixed with 0.5 ml of a di lute ,aqueous solut ion of ferr ic chlor ide containing one ortwo drops of acet ic acid (or of di lute hydrochloricac id ) . To the mixed solut ion are added one or twodrops o f an aqueous so lu t ion o f hexahydroxybenzene .A br igh t - red p rec ip i ta te of bar ium rhodizo na teresu l t s .

3 Unless the product is thoroughly washed, it may contain traces of tin salts.The presence of tin can be determined by dissolving a sample in nitric acid,evapo rating the solution, and igniting the residue. Wh en the recrystallizationis conducted properly, this test does not provide any appreciable final residue.Use of stannou s chloride, in the recrystallization prev ents th e formation of unde-s ired oxida t ion prod ucts .

(c) [9] One ml of a "dilute, aque ou s solutio n ohexah ydroxy benze ne i s mixed wi th 1 ml o f a sa tura ted , aqueous so lu t ion o f magnes ium n i t ra te , and few drops of d i lu te amm onia a re added . A carminered p rec ip i ta te resu l t s .3 . Tetrah ydrox y-p-be nzoq uinon e (I I) [17]

3 . 1 . DiscussionThe prepara t ioD of t e t rahydroxy-^ -benzoquinone ibased on the self-condensat ion of glyoxal in the presence of sod ium sulfite, air, and a ba se. T he pro cedure was or iginated by Homolka [15] , and has beenstudied and modif ied by subsequent workers [18, 1920]. Presum ably , hexah ydroxy benzene i s fo rmedin i t i a l ly ; th i s i s ox id ized to t e t rahydroxy-^ -benzoquino ne, and this , in tur n, to rhodiz onic acid. Ashown by Fat iad i and Sager [13] , wh en sodium bicarbonate is used as a buffer , the disodium sal t otetrah ydro xy- p-be nzo quin one is formed in a yield o8 to 11 perce nt . W hen the react ion mix tur e is highlalkal ine, substant ia l quant i t ies of disodium rhodizonate and disodium croconate are formed, in addi t ion

to the d i sod ium sa l t of t e t rahydro xy-p-b enzo quinon e3 . 2 . Preparation of the Disodium Salt of Tetrahydroxy-p-benzoquinone [ 13]A solution of 400 g (3.17 moles) of anhydroussod ium sulfite an d 150 g (1.79 moles) of sod ium bic ar-bonate in 3 l i ters of water is placed in a 5-liter, t h r e enecked f lask f i t ted with a thermometer , an air inletube (1 -cm d iam) , and a tube connec ted to a wate rasp irator . Th e solut ion is hea ted to 40 to 45 Cand 600 g of a 30-percent , aqueous solut ion of glyoxa(3.1 moles) is adde d. A brisk s t rea m of a ir is draw nthrou gh the so lu t ion fo r 1 h r wi tho u t hea t in g , a f te

which th e mix ture is grad ual ly h eate d to 90 CAer at ion is then s topp ed, and the m ixtu re is hea ted toincipient boi l ing and cooled to room tem pe rat ur e .The resul t ing, crystal l ine disodium sal t of I I is removed by f i l t ra t ion, washed successively with 50 mof cold, 50-percent , aqueous methanol and 50 ml ofme thano l , and dr ied in a vacu um des icca to r . Th eyield (22 to 24 g) corresponds to about 10 percent ofthe theore t ical , based on the glyoxal used. Th e pro d-uct can be used witho ut purif icat ion for th e pre pa rat ion of te t ra hyd rox ybe nze ne, rhod izonic acid, orcroconic acid. I t is sensi t ive to oxidat ion b y air andif s tored in a loosely s toppered bot t le , is completelyox id ized to d i sod ium rhodizo na te in severa l m on ths .Te t rah ydrox y-p-be nzoqu inone i s , however , r e la t ively s tabl e in a ir .

3 . 3 . Preparation of Tetrahydroxy-p-benzoquinoneThe crude disodium sal t of I I (20 g) is dissolvedin 220 ml of 2.5-N hydroch lor ic ac id by hea t ing .On cool ing, the solut ion yields gl is tening, blackcrys ta l s of t e t rahydrox y-p-ben zoquino ne which a recol lected by f i lt ra t ion, washed with ice wa ter , anddried in a va cu um des iccato r ; wt , 12 to 15 g. Th eproduc t i s rec rys ta l l i zed f rom warm, 2-N h y d r o -

154


3/10

rk crys ta l s . Spe ct rogra ms are g iven on pages 1584 . Rhodizonic Acid (III) [21]

4 . 1 . DiscussionHere tofore , rhodizonic ac id ( I I I ) , t he oxidat ionoino s i to l w i th n i t r i c ac id [11] , by r ed uct ion of

om glyoxal [15]. Desc r ibed below are the p repa raf am mo niu m rho dizo nate [21] f rom glyoxal ,

Preparation of Tetrahydroxy-p-benzcquinoneand Ammonium Rhodizonate from GlyoxalAqueous glyoxal (600 g of a 30-percent solut ion)

tion 3.2. After 1 hr of ae rati on , 100 g of so diu mroxide i s add ed. Th e a lka l ine so lu t ion (pH 10 )hea ted , w i th aera t ion , to inc ip ient boi l ing , an ded to room tem pe ra tu re . Th e mix ture ofd wash ed successive ly w i th 50 ml of cold, 50-t hano l and 5 0 m l of m e t hano l .

2.5-N hydrochlor i c ac id by boi l ing , and4 T h eta l l ine I I (8 to 9 g) is sep ara te d byT he ice-cold, da rk-r ed f i l t rate i s bro ug ht to5 .5 to 6 .5 wi th amm onia . Th e r esul t ing , dark -c r ys t a ll i ne am m o ni um r hod i zon a t e i s s epa r a t ed

r ied ; wt , 7 to 8 g. I t i s recry stal l ized f rom

4 . 3 . Preparation of Rhodizonic Acid from theDisodium Salt of IITh e disodiu m sal t of I I (40 g) , pre pa red as descr ibedis pla ce d in a larg e, f lat-bottomed dishd heat ed in an oven at 170 to 180 C for 24 hr .200 ml of w arm , 2.5- iV hyd roch lor ic acid, an d af term inute s , 1 g of decolor iz ing carbon i s ad ded ;e solut ion is cooled in ice an d f i l tered thro ug hf il te r pa pe r preco ated wi th pap er pu lp . Th eon is con cen t ra t ed und er

. Th e r es idue i s t r i t u ra t e d wi th 50 ml oftone , th e suspensio n is f i ltered, and th e insolubledu ct i s wa she d wi th sufficient cold aceton e to^Prolonged heating causes disproportionation [22].

r emo ve a l l co lored impu r i t i es . Th e crys ta l l ineresidue, consist ing of sodium chlor ide and cruderhodizonic ac id d ihy dra te , is a i r -dr i ed and pulver i zed ,and the powder i s added to 200 ml of d ioxane prehe ate d to 80 C. T he sus pens ion is st i r red for 5min and then f i l tered through a f i l ter paper precoatedwi th decolor iz ing carbon . Th e insoluble m at t er iswashed wi th 50 ml of warm dioxane , and the s l ight lycolored f i l t rate i s cooled to ab ou t 20 C . Pe nt an e(abou t 150 ml ) is add ed to inc ip ient turb id i ty , andcrystal l izat ion of rhodizonic acid dihydrate i s induced by scra tching the ins ide wal l s of the conta inerwit h a glass rod. Th e mixt ure is cooled in ice forab ou t 30 min , th e suspension is f i ltered, and th ecrystals are washed wi th 50 ml of a cold, 1:1 mixtureof d ioxane and p enta ne , a nd a i r -dr i ed ; wt , 25 to 35 g .The crude rhodizonic ac id d ihydra te i s r ecrys ta l l i zed f rom warm dioxane by the addi t ion of pentaneand e ther ; by concent ra t ion of the f i l t r a t e , an addi t ional c rop i s obta ine d . Th e a ir -dr ied p rodu ct ,which st i l l contains dioxane, i s dr ied for 48 hr ina va cu um desic cator over sul fur ic acid ; tot al y ield,ab ou t 21 g (60% ) of colorless crys tals . M easu reme ntsof inf rared and ul t raviolet absorpt ion are repor tedon pages 158 and 160.The pu r i t y o f t he p r oduc t m ay be de t e r m i ned byt i t rat ion wi th iodine [20] ; 155 mg of rhodizonicacid dihy dra te cons um e 14.97 ml of 0 .1- iV I3 solut ion; found, 15.07 ml .I f subjec ted to a h igh vacu um (0 .1 mm ) a t ro omtempera ture the compound i s conver t ed in to thescar l e t - r ed crys ta l s of anh ydro us rhodizon ic ac id in asl i t t le as 5 min . Th e sam e t r ansform at ion can beaccom pl i shed a t h i ghe r t em per a t u r e s by vacuumsub l ima t ion [20]. Rh odiz onic acid gives a color lesssolut ion in 2.5- iV hyd roch lor ic acid, wh ereas te t ra -hydroxy-p-benzoquinone g ives a cher ry- red so lu t ion .5 . Triquinoyl (Cy cloh exa neh exo ne, IV) [23]5 . 1 . Discussion

In 1862, Lerch [24] obta in ed a product , now know nas t r iquinoyl , by oxidat ion of e i ther hexahydroxy-benzen e ( I) or t e t r ahyd roxy -p-ben zoq uinon e ( I I ) wi thni t r i c ac id or ch lor ine . Th e sub s tanc e has beencha racter ize d by N ietzk i and cow orkers [8, 10, 25] ,an d studie d by He nle [26] , Berge l [27], an d E ist er tan d cowo rkers [20, 22] . Th e proc edu re descr ibedhere is based on the or iginal work of Lerch and ofNie tzk i . Becaus e some worker s hav e exper ienceddif f icul ty in the preparat ion and pur i f icat ion of IV,the procedures are g iven in de ta i l .5.2. Preparation of Triquinoyl Octahydrate

Recrys ta l l i zed t e t r ahyd roxy -^-ben zoq uinon e (10 g)i s added in smal l i ncrement s dur ing 5 min to a mechan ical ly st i r red solut ion of 100 ml of c on cen tratenni t r ic acid an d 25 m l of w ate r ke pt at 10 C. Th ereact ion i s cont inue d for an addi t iona l 5 min , 25 mlof water i s added, and the mixture is cooled in icefor 15 min . Th e crys ta l l ine t r iquino yl oc ta hy dra tethat separates is f i l tered off , washed successivelywith 20 ml of ice water and 30 ml of an ice-cold,155


4/10

1: 1 mix ture o f ace tone a nd e ther , an d a i r -d r ied ;wt, 12 to 12.5 g; mp 96 to 97 C.The substance is recrystal l ized in the fol lowingm an ne r : Th e oc t ahy dra te (5 g ) i s suspended in 50 mlof me than ol con ta in ing 3 ml of conce n t ra ted n i t r i cacid, and the suspension is heated to 55 to 60 C,wi th s t i r r ing . W hen d i sso lu t ion i s comple te , abou t200 mg of decolorizing carbon is added, the suspension is f i l tered, and the insoluble matter is washedwi th 25 ml of wa ter . Th e com bined f il trate a ndwash ings a re evapora ted under d imin ished pressureto about 25 ml, and the solut ion is cooled in iceun t i l c rys ta l l i za t ion beg ins , and then g radua l lydi lute d wit h 20 ml of aceto ne. Th e crysta ls arecollected on a filter, washed successively with 10 mlof cold 1: 1 aceto ne-w ater mi xtu re a nd 20 m l ofcold aceto ne, and air-dr ie d; wt , 2 .1 g . B y concen t ra t ion o f the mother l iquor , add i t iona l mate r ia l(0.6 g) is obt aine d. Th e oc tah yd ra te consis ts ofcolor less , lustrous plates or pr isms, mp 99 to 100 C(decomp os i t ion) . In f ra red and u l t rav io le t absorpt ion spectra are recorded on pages 159 and 161.A cha racte r is t ic color tes t [26] for IV involvesh e a t i n g t h e c o m p o u n d w i t h a s a t u r a t e d , a q u e o u sso lu t ion of bar ium ch lor ide ; b r igh t - red bar iu mrhod izona te is p rec ip i ta te d , fo llowing d i spropor t iona-tio n [8, 221.

6. Croconic Acid (V) [28]6 . 1 . Discussion

Croconic acid (V) is one of the first enediolic acidsto hav e been repor te d . S ince i t s d i scovery byGm elin [29] in 1825, i t has engaged the at te nt io n ofm an y workers [10, 30-39] . As po in ted ou t byH ira ta a nd coworkers [36] , the an ion has an u nusu a lreson ance s t r uc tur e . Croco nic acid is formed froma var ie ty o f po lyhydroxybenzene der iva t ives byoxida t ion fol lowed by a rea rran gem ent of the benzy l icacid ty pe . I t can be effic iently prepar ed by oxidat ion o f t e t rahydroxy-p-benzoquinone or rhod izon icacid with man gan ese dioxide. In the process , thebenz ene r ing is deg raded , with el iminat ion of carbondiox ide. Th e reac t ion was d i scovered by N ie tzk i[32] and has s ince been used by many workers .Th e p rocedure g iven here resembles one descr ibed byY am ad a and H ira ta [40] , and differs from prio rmethods in tha t i t s t a r t s wi th the c rude mix ture o fsodiu m sal ts obtain ed from th e conden sat ion ofglyoxal ( instead of with pure sodium rhodizonate)and uses a special type [41] of act ive manganesedioxide as the oxidant .

6.2. Preparation of Active Manganese DioxideCom merc ia l manga nese ca rbo na te (500 g ) in aflat-bottomed tr ay or dish is he at ed in an ove n at295 to 310 C for 12 to 18 hr . After be ing cooled,the product is t reated with suff ic ient aqueous ni t r icacid (15 to 20 ml of concentrated acid per 100 ml ofso lu t ion) to decompose any res idua l ca rbona te andto give a s t ro ng ly acid solut ion. After 30 to 45

min, the manganese dioxide is filtered off, thoroughlywashe d with water , an d dr iedf at 150 to 160 C fo18 to 24 hr . After i ts recov ery from react io n mixtures , ac t ive manganese d iox ide can be usedrepeatedly if i t is redried at 150 to 160 C for 18 to24 hr . M angan ese d iox ide p repa red by o themethods proved to be less sat isfactory.6 . 3 . Barium Croconate Hydrate

To a solu tion of 40 g of sod ium hyd rox ide in 1.2l i ters of wa ter are adde d, with s t i r r ing, 21 g (0.mole ) o f c rude d i sod ium te t rahydroxy-p-benzoquino ne (see sect ion 3.2) an d 55 g of act ive ma nga nesedioxide. After 5 min, the mi xtu re is he ate d toboiling, refluxed for 45 mi n, an d filtered, an d th emanganese dioxide is washed with 800 ml of howa ter . Th e comb ined f il trate and wash ings aret rea ted wi th about 210 ml o f concen t ra ted hydrochloric acid in port ions, giving a br ight-yel lowsolut ion. To this is adde d a ho t solut ion of 50 gof bar ium chlor ide dihydrate in 150 ml of waterwith s t i r r ing; the m ixtu re is hea ted to 85 to 90 Ccooled , and kep t a t room tempe ra tu r e . Th e resul t ing, lustro us, yel low plates of ba r iu m crocon atemonohydrate are col lected on a f i l ter , washedsuccessively with water and ethanol , and air-dr iedwt, 22 to 23 g.6 .4 . Conversion of Barium C r o c o n a t e t o SodiumC r o c o n a t e

Barium croconate (17.5 g; 0.06 mole) is added insmall port ions, with s t i r r ing, to 150 ml of a 10percen t aqueous so lu t ion o f anhydrous sod iumcarb ona te . Th e mix ture is boi led for 5 min an dfil tered; the bar iu m carb ona te is was hed with 30m l of ho t w ate r, and the com bine d yellow filtratand wa shing s are dilu ted wi th 20 ml of glacial aceticacid, hea ted to boi l ing, and cooled in ice . Disod iumcrocona te t r ihydra te separa tes in long , ye l lowcry stal s, wh ich are collected on a filter, wash ed wi th40 ml of ice water , and air-dr ied; wt , about 10 gA second crop (2.5 to 3 .5 g) is obtained by addingabout 200 ml of 95-percent e thanol to the mothel iquor and cool ing the solut ion.Dipo tass ium crocona te may be p repared s imi la r ly

6 . 5 . Croconic Acid Tr ihydra teBa rium crocon ate (55 g) is add ed in small p ort io nto 200 ml of mechanical ly s t i r red, aqueous sulfur ic

acid (containing 20 ml of concen trated acid) a t 55to 60 C ; s t i r r ing is cont in ued for 30 to 45 mi n. Th ebar ium sulfate is sep arate d by f il trat ion, was hed with25 ml of ho t wate r , and discarded. Th e com binedfil trate and washings are eva pora ted to dryn ess un dediminished pressure, the res idue is dissolved in a hosolution of 25 ml of absolute ethanol and 150 ml ofdioxane, and the solut ion is t reated with a smalqu an tit y of decolorizing carb on an d filtered. T hefil trate is con cen trated un der diminished pressure a40 C unt i l crystal l izat ion begins , and the mixture isdi luted with benzene to incipient turbidi ty and cooled.156


5/10

a vac uum des icca tor . By concen t ra t ion of theg . Inf rared and u l t r av io le t absorpt ion spect r a are

An hyd rous croconic ac id i s prep ared by hea t ingabo ve 150 C. Croconic ac id m ay be

Smal l quant i t i es of c roconic ac id may be preparedssing a solut ion of 5 g of disodium croc ona te in(Am ber l i te 1 20 -H+ ) , con cen trat ing th e ef fluenter d imini shed pressure , and crys ta l l iz ing the pro d

6 . 6 . P r e p a r a t i o n of M a n g a n e s e C r o c o n a t eTr i hyd r a t eA solut ion of 5 g of croconic acid t r ih yd ra te in

e unt i l a prec ip i t a t e forms. Th e mix ture i s cooledcrysta ls are sep ara ted b y f il trat ion. T he pro du ctrecrystal l ized f rom w ate r b y the ad di t ion of ace

Analysis: Calculated for C 5 M n 0 5 3 H 2 0 : C , 24 . 1 ;, 2 .41 . Fo un d: C , 24 .0 ; H , 2 .5 .6 .7 . Analys i s of Croconic Acid

The pur i ty of samples of croconic acid may bem perm ang an ate ( see eq (1)) .

4 + 23 H 2 S 0 4 + 5 Na 2 C 5 0 5 -* 6 K 2 S 0 4 +12 M n S 0 4 + 2 5 C 0 2 + 5 N a 2 S 0 4 + 2 3 H 2 0 (1)

A 50-mg sample of disodium croconate, previously120 C for 1 hr , i s t ransfe rred to a 25 0-mlnm ey er flask wi th 25 to 50 m l of wa ter . Sulfuricid (50 m l of 3.6 N) i s added, and the solut ion isf the or iginal yel low color . Th en 5 m l of a

, is pro duc ed. A 50-mg sam ple of disod ium1-2V potass ium pe rm an gan ate ; ca lcula t ed fora 2 C 5 0 5 H 2 0: 29.40 ml .

Leuco nic A cid (Cy clopenta nepen tone, VI)[42]7 . 1 . Discussion

Leuconic acid was f i rst prepared by Wil l [43] in

1861. Par t i cu lar ly notewor thy inves t iga t ions werema de by N ie tzki [32] , Hom olka [44], and E i s t er t andcoworke rs [22] . Th e proc edu re given in the pres en tpaper i s a modif icat ion of that of Nietzki .

7 . 2 . P r ep a r a t i o n of Leucon ic A c i d Pen t ahy dr a t ePur i f ied an hy dro us croconic acid (2 g) , or a nequivalent amount of the t r ihydra te , i s added inpor t ions, wi th st i r r ing, to 20 ml of ice-cold, concent r a t ed n i t r i c ac id dur ing 3 min , and th e mixture i sst i r red unt i l evolut ion of ni t rogen dioxide ceases(abou t 10 min ) . Th en 20 ml of i ce-cold me than oli s added, and the mixture i s s t i r r ed whi l e crys ta l l izat ion of leuconic acid pentahydrate occurs; af ter10 min , the crys tals are sep ara ted by f il trat ion,washed wi th methanol , and a i r -dr i ed ; wt , about2.7 g.For r ecrys ta l l i za t ion , the compound i s d i sso lvedin the minimal quant i ty of water ; t he so lu t ion i st reated wi th decolor izing carbon and f i l tered, andthe f il trate i s con cen trated un der diminished press ureat 40 C to abo ut 5 ml . Af ter the add i t ion ofseveral drops of concentrated ni t r ic acid, the solution, on cooling, yields colorless crystals of leuconicacid pe nta hy dra te . Inf r ared and u l t r av io le t absorpt ion spectra are given on pages 159 and 161.Crys ta l l ine l euconic ac id pentahydra te may bei so la t ed f rom concent ra t ed , aqueous so lu t ion byadding a 1:1 mixture of 2-propanol and ethanol ;this product i s devoid of ni t r ic acid.The pen t ahydr a t e m e l t s w i t h dehydr a t i on a t 115to 118 C, fol lowed by slow decomposi t ion at 158to 162 C. Leuc onic acid m ay be chara cter ized asthe pen taox ime [32] , m p 172 C. In the pre sen ts tudy, i t has been found tha t the oxime may convenient ly be recrystal l ized f rom N,A^dimethylforma-

m i de .When a sa tura ted so lu t ion of sodium carbonate i sadded to an aqueous solut ion of leuconic acid, apink color i s produced, fol lowed by deposi t ion of adi f f icul t ly soluble, whi te precipi tate of the sodiumsalt of mesoxalic acid [44].

8. Spectrophotometric MeasurementsFigure 1 r epo r t s inf r ared spect rogram s for thef reshly prepared , c rys ta l l ine compounds in Nujolm u l l s . The m easu r em en t s w er e m ade w i t h aPerkin-Elmer Inf racord Model 137 (double beam)

spect rophotometer equipped wi th a pr i sm of sodiumchloride for the 2- to 15-/* r ange .The u l t r av io le t absorpt ion measurement s g ivenin figure 2 were m ade wi th a Be ckm an D K -2spect rop hotom eter wi th ma tched , 1-cm qu ar t z ce ll sand the ap prop r i a t e so lvent as the r eference s t an da rd .In the course of t ime , the sp ectra for some of thecompounds change, presumably f rom oxidat ionreac t ions . To minim ize oxid at ion, freshly boi ledsolvents were used, but complete exclusion of oxygenw as no t a t t em p t ed .


6/10

4000 3000 2000 1500n u n 11 i i i i i i i i 1 i i i i i i i i i I i

1200 1000 900 800I I I I I l l 1 1 1 1 1 I I I I I I I I I I I i I I I I

700I I I 1 I I I

8 9 10WAVELENGTH,^

1 0 04 0 0 0 3 0 0 0 2 0 0 0 1 5 0 0

,111111111 l l II I I I I I I I I I I I I I I I I i I Ic m - 1

1200I 1 I I

1000 900 800 700I I I I I I I ni l i i L I I I I I . I I I . I I

8 9 10WAVELENGTH,^

c m - 1400 0 3000 2000 1500 1200 1000 900 80 0 70 0

I I I I I I I l l i i i i i i i i I i i i i i i i i i I i L_ I i i_J u__i i li i n it i i 11 i i i i i i i i i I i i i i i i i i i I i i I100 P

\t I i I i I i I . I i L J I l I I I L.3 4 5 6 7 8 9 10 II 12 13 14 15

WAVELENGTH, p.

F I G U R E 1. Infrared spectrograms of materials in Nujol mulls.I, Hexahydroxybenzene; II, tetrahydroxyquinone; III, rhodizonic acid dihydrate.

158


7/10

4000 3000 2000 1500In n li I i i l i L

c m " 11200 1000 900 80 0- i li 111111111 i i i i i i I I i I i 7 0 0I . . .,

8 9 10WAVELENGTH,/x

4 0 0 0 3 0 0 0 2 0 0 0 c m "1200too FL I 1 1 1 1 1 1 1 1 l l I I I I I I I 1 1 1 I I I I I 1 I 1 1 I I I I I L

1000 900 80011 n 111 i i 11 i i i i i i i i i I i i i 7 0 0 I , , ,

to 40

J I I I I I I I I L _L J I I I I I I L8 9 10W A V E L E N G T H , ^ 12 13 14 15

4000 3000 2000 1500 1200 1000 900 800 7 0 0

]} -J-I 1 1 1 IL I I I I I I I L_L4 5 6 7 8 9 10WA V E LE N GTH , / / . 12 13 14 15

F I G U R E 1. Infrared spectrograms of materials in Nujol mullsContinuedIV, Triquinoyl octahydrate; V, croconic acid trihydrate; VI, leuconic acid pentahydrate.

67068263 6 15 9


8/10

.3LJ5?00orOin9 1< '

0

1 1

//

ii i

\ /vA/ \/ \' \\ \ \i 1 i _L ,

1 i 1 1 1 1A

\ Nw"^ ^ s ^ ..L^r^i-^b^,!

I

_,I

i250 260 270 280 290 300WAVELENGTH, m/J. 320 340

3 h2< 1 .2

alexander j. fatiadi et al- cyclic polyhydroxy ketones. i. oxidation products of hexahydroxybenzene...

Documents