C/s-butenedioic acid

Exercise 15-12 The diethyl ester of c/s-butenedioic acid can be prepared by heating the corresponding anhydride with ethanol and concentrated H2S04 in benzene in a mole ratio of perhaps 1 2.5 0.25. 

In dicarboxylic acids that are capable of forming intramolecular hydrogen bonds, it is observed that the first proton is removed more easily than would be predicted by just considering the inductive effect of the second carboxylic acid. Suggest the structure that c/.s-butenedioic acid adopts after one deprotonation. 

The effect is very pronounced, but falls off sharply as soon as the carboxyl groups are separated by more than one saturated carbon atom. C/ s-butenedioic(maleic) acid (5, pKal = 1-92) is a much stronger acid than trans-butenedioic(fumaric) acid (6, pX,1 = 3-02), due to the intramolecular hydrogen bonding that can take place with the former, but not with the latter, leading to relative stabilisation of the cis (maleate, 7) mono-anion (cf. o-hydroxybenzoic acid above) ... 

Figure 11.1 Py/methylation GC/MS chromatograms of lead white pigmented linseed oil paint after 610 °C Curie point pyrolysis assisted with on line methylation using 2.5% methanolic TMAH (the sample and TMAH solution was applied onto a rotating Curie point wire pyrolysis time 6 s, interface 180°C). 1, heptenoic acid, methyl ester 2, heptanoic acid, methyl ester 3, butenedioic acid, dimethyl ester 4, butanedioic acid, dimethyl ester 5, octenoic acid, methyl ester 6, octanoic acid, methyl ester 7, pentenedioic acid, dimethyl ester 8, pentanedioic acid, dimethyl ester 9, nonanoic acid, methyl ester 10, hexanedioic acid, dimethyl ester 11, decanoic acid, methyl ester 12, heptanedioic acid, dimethyl ester 13, octanedioic acid, dimethyl ester 14, 1,2 benzenedicarboxylic acid, dimethyl ester 15, a methyl octanedioic acid, dimethyl ester 16, nonanedioic acid, dimethyl ester 17, a methoxy octanedioic acid, dimethyl ester 18, a methyl nonanedioic acid, dimethyl ester 19, a,a dimethyl nonenedioic acid, dimethyl ester 20a, a methyl nonenedioic acid, dimethyl ester 20b, a,a dimethyl nonanedioic acid, dimethyl ester 21, decanedioic acid, dimethyl ester 22, a methoxy nonanedioic acid, dimethyl ester 23, a methyl decan edioic acid, dimethyl ester 24, undecanedioic acid, dimethyl ester 25, a methoxy decan edioic acid, dimethyl ester 26, pentadecanoic acid, methyl ester 27, dodecanedioic acid, dimethyl ester 28, hexadecanoic acid, methyl ester 29, heptadecanoic acid, methyl ester 30, octadecanoic acid, methyl ester 31,8 methoxy 9 octadecenoic acid, methyl ester 32, 11 methoxy 9 octadecenoic acid, methyl ester 33, 9 methoxy 10 octadecenoic acid and 10 methoxy 8 octadecenoic acid 34, 9 oxo octadecanoic acid, 10 oxo octadecanoic acid 35, 9 epoxy octadecanoic acid 36, eicosanoic acid, methyl ester 37, 9,10 dimethoxy octadecanoic acid, methyl ester 38, docosanoic acid, methyl ester. Reprinted from J. Anal. Appl. Pyrol., 61, 1 2, van den Berg and Boon, 19, Copyright 2001, with permission from Elsevier...

Exercise 18-51 The c/s- and frans-butenedioic acids give the same anhydride on heating, but the trans acid must be heated to much higher temperatures than the c/s acid to achieve anhydride formation, Explain, Write a reasonable mechanism for both reactions,... 

Citraconic Acid. 2-Methyi-2-butenedioic acid methylmaleic acid. C H604 mol wt 130.10. C 46.16%, H 4-65%, O 49.19%. Obtained by carefully heating citric acid at about 175. Production o( citraconic anhydride from ita -conic acid Humphrey. U.S. pat. 2.966,498 (i960 to Pfizer). 

SOOSP2C4JH34, Osmium, carbonyl(S-thioxo- 1,3-pentadiene- l,S-diyl-C, C ,S) bis(triphenylphosphmeK 26 188 S02C7Hg, Benzenesulfonic acid, 4-methyl-, rhodium complex, 27 292 S04PC(H 2, 2-Butenedioic acid, 2-(dimethylphosphinothioylK dimethyl ester, manganese complex, 26 163 SOgCijHij, Thiophenetetracarboxylic acid, tetramethyl ester, 26 166 SO,oOS]C,o. Osmium, /ij-carbonylnona-carbonyl- 3-thio-tri-, 26 305 SOjoOsjCigHt, Osmium, (it-... 

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