Tsuchiya Ryokichi

Uehara Akira

上原 章

土屋 亮吉

Kanazawa University Repository for Academic Resources

ScL ReJPl. KaIT1lazawa Ulf!iv.， VoL 25， N o.2， p. 83-85 A N ew Synthetic Route to Squa:ric Add as a Chelatiing Agent Akira UEHARA and Ryokichi TSUCHIYA Faculか J(anaZaU)(i ( Received January 6， 1981) Ahst.raet A conveni日ntmethod was established for th日 preparationof squaric acid as a chelating age口t. '1、hemethod is characteriz己dby (i) the choice of easiIy avai.!alコlehexachloro-l，3-butadi在日記 (HCB) as th号 starting material， (ii) the usε of catalytic呂mountsof iron for cydization and hydrolysis， (ii) nO l1se ()f any spedal apparatus such as autoclav在日ndcorrosion-resisting vessel， and (iv) no indusion of any comp!icated procedurで Aninteresting bilaterai chelatin宮、characteroI the acid was ah~o describモdoacid') isan chelating agent for both and coordination chemists because of its bilateral bridge-formation character as well as the presence of aromaticity.2) HO¥vever・ヲ the acid is sti1l puzzling in the fie1d of coordination chernistry. The main reason is that no suitable method 1日ISbeen knovm for the compound withont any trouble on a scale. For 'Norkers desiring to prεpare small amounts of the COi1TDOUnd司 the 3) and its modified methods4) may stil be used; hO'Jvever the:，e are as a to obtain amounts of the compound to be utiiized route to succeeded in finding a new conv合nientmethod for The paper is thus concerned with the synthetic acid and thεbilateral character thereof as a chelating agent. Pl'cpaliaiion r(]!f Aci.d Our ]Jrocεdure is out1ined as Iollows : ????二二CCl一CCl=CC12 ω2ニ CClmtC〈 GL2H5ムHOC~_ 一一C=OHOC''-一一一 =0?? ??? 口己:;df(HCB). Reagen of HCB was 83ー ←84 Akira UEHARA and Ryokichi TSUCHIY A from Wako Pure Chemical Ltd 1- T~沿 hundred and ten grams (0園 ofHCB and a solution of 28 g oI metallic sodium in 500 ml of absolute ethanol were into a litre-flask with a reflux condenser. The mixture was heated for 2 h.In this stage， care should be taken to 8!void 】duetotheethoxylation. After sodium chloride was filtered ex印 ssethanol was distilled oul: from the fHtratε.τhe remainder was then distilled at 130"C under 20 to 95 g of colorlessヲSVJeeト 1，2，3， 4， 3 butadiene. (HI) Perchlorobiがたnoηe. five grams (O.35mol) of I and amounts 3 mg) of iron were in a 300 ml flask eQuipped with a reflux condenser. The mixture was heated at 160-180oC for 30 min with occasional Black oil of a irritating odor VIT8.S thus obtainea， which was distil君dat 18QoC under 20 to give 69 g of faintly sむ叩ricAcid. nine grams of HI， 300 ml oI 5ulfuric acid and amounts (about 3 mg) of iron were put in a 500 ml flask with a reflux condenser. The content was heated ai: 1600C for 2-3 h with continuous The addition of iron in amounts was effective to promote When the iron was thεof the desirεd '0!aS reduced. The mixture was then allowed 1:0 stand in a erator. ViThite crystals were 500n obtained and were recrystallized from hot water. Yield 15 g. Found: ，二 42.18; Calcd for 04: C， 42J←2; H， BnRaterai Chmracter of Addl acid generally resembles oxalic acid in coordination behavior toward metal but the former is to the !attεr in both and reducing abi!ities，5) The most aUractive point of the squarate ion is its bilateI叫 character; the ion has a potency of towara two metal Ions This makes it possible to find a new reaction pattern of metal complexes in the solid-ph設se. 1n fact， the model complex (NHJ 6 ] [Al ] which we underwent a very interesting reaction upon heating as shown below : ifit，TTT ¥ .0._/0 r. ¥. 1'. ~jr. I.r.. ¥ 1 [Cr(Nf-U6J [Al ‘ [(NH3)4Cr(C，04)Al(C404)2 ]一一一一一一→413J 70-1000C 'L¥>" ¥V''-'j1CU¥v4'-'I2J 120-1800C 'V .. vV v pink ] green In the reaction， squarate ion coordinated to Al (II) to Cr ion via the formation of an intermediate in which the squarate ion functions toward both metal ions. AN日wSynthetic Rout日toSquaric Acio 85 Refer思flces1) The names刊squaricacid" and "squarate" for 3，4-dihyaroxy-3-cyclobutene-1，2-dion邑 andits dianion have come from squar己planarstructure. For convenience， both thεnam巴sare used in this pa per. 2) a) J. Aihara， Bull. Chern. Soc‘JPn・， ，17， 2899 (1974); b) W. M. MacIntyre and M. S. Werkema， I Chem. Pl，り5.，40， 3563 (1964)ー3) J. D. Park， ].R. Lacher， and S. C口hen，f. Am. Chern. 50c.， 81， 3480 (1959) ; 84， 2919 (1962) 4) M. Ito and R. Wεst， ].Am. Chem. 50c.， 85， 2580 (1自63)5) R. Tsuchiya， A. Uehara， M. Sakui， and E. Kyuno， Chem. Let.， 19H， 1511 

A New Synthetic Route to Squaric Acid as a chelating Agent

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A New Synthetic Route to Squaric Acid as a chelating Agent

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