The reaction of an aromatic heterocycle with a proton is called a protonation. One of articles about this theory is 《Configuration determinations in the terpene series. II. The optically active forms of β-isopropyladipic acid and their relation to the optically active limonenes》. Authors are Braun, Julius V.; Werner, Georg.The article about the compound:cis-Cyclohexane-1,2-dicarboxylic acidcas:610-09-3,SMILESS:O=C([C@H]1[C@@H](C(O)=O)CCCC1)O).Quality Control of cis-Cyclohexane-1,2-dicarboxylic acid. Through the article, more information about this compound (cas:610-09-3) is conveyed.
cf. C. A. 20, 2990. It was shown in the 1st paper that the configuration of the C atom carrying the Me group in the natural d-rotatory citronellol, the d-rotatory citronellol, pulegone, the d-rotatory menthone and l-rotatory menthol is the same and corresponds to that of the d-rotatory pyrotartaric (I) and of the d-rotatory β-methyladipic acid (II) when the formulas of these compounds are so written that the valence to the O-containing part of the mol. (or the nearer CO2H group in the case of II) of the asym. C atom corresponds to that through which in I the CO2H group is held. This was shown by establishing the genetic relationship between I and the II which is obtained by the oxidative degradation of some of these compounds It is probable, although not definitely proved, that this configuration corresponds to that of d-tartaric acid and the prefix d-is accordingly used for the Me-carrying C atom in this series of compounds These results gave rise to the desire to determine whether there is a similar simple relationship as regards another asym. C atom often occurring in this class of compounds, viz., the C atom, usually in the 4-, more rarely in the 3-position to the CHMe group, canying the iso-Pr or isopropenyl residue, and which either alone (as in limonene, carvone, diosphenul, silvestrene) or together with the CHMe group (as in menthone) conditions the optical activity. It is known that in some cases this C atom call be oxidized out as isopropylsuccinic acid and in others as β-isopropyladipic acid (III). Here, however, the problem was much more difficult, for there were in general no exact data in the literature oil the optical activity of the 2 expected iso-Pr-containing di-CO2H acids, on the d- and l-forms prepared artificially by resolution of the dl-forms and, naturally, on the genetic relationship between the tartaric acids and there acids; finally, the inactive III is extraordinarily difficultly available. The 1st problem attacked, therefore, was that of preparing III in sufficient quantities. A repetition of Blanc’s work convinced v. B. and W. that this method would not be practical but the fact that p-methylcyclohexanol readily yields II on oxidation suggested the use of p-isopiopylyleyclohexanol (IV) as the starting material. p-iso-PrC6H4OH was readily hydrogenated with Ni at 150° to IV and this, after some experimenting to determine the proper conditions, was converted with satisfactory yield into III which by means of strychnine was resolved into the d-rotatory form with maximum rotation and the l-rotatory form with not quite a constant final rotation. To oxidize the optically active 4-C atom out of limonene the 8,9-double bond naturally had first to be eliminated. This, it was found, could not be effected by adding HCl, for extensive racemization. occurred in the process and by varying the length of the HCl treatment hydrochlorolimonenes with widely different rotations could be obtained. On the other hand, the dihydrolimonene (V) obtained by hydrogenation of pure d-rotatory limonene with H2 and Pt gave an optically active ketoaldehyde (VI) and keto acid (VII) and the latter finally yielded a III with the same rotation as that obtained by resolution of the dl-form. On the very probable assumption that, like-the d-rotatory II, it belongs to the d-series, the d-rotatory hydrocarbon would then be represented by the symbol d(+)-limonene. dl-III, obtained in 50% yield from IV (in not more than 10 g. portions) shaken 8-10 hrs. below 10° with 3 parts KMnO4 and 0.5 part KOH in not quite 100 parts H2O, b12 215-8°, m. 75°; di-Et ester, b12 145-50°, d420 0.9776. Strychnine salt of (+)-acid, m. 182°; Na salt, [α]D 5.4°; free acid, m. 66°. (-)-Acid, m. around 60° ; Na salt, [α]D -4.1°. Chloride of the (+)-acid, prepared with cold SOCl2, b16 145-6°, d420 1.1023, [α]D20 1.134°; amide, m. 169.5°, [α]D20 9.5° (2.22% aqueous solution); Et ester, prepared with HCl and alc., b13 145-50°, d420 0.9776, [α]D20 -1.534° (no solvent). With HCl very carefully dried with H2SO4 and P2O5 v. B. and W. obtained, after saturating limonene in CS2 for 6 hrs., an analytically pure HCl addition product, b16 100-1°, with [α]D 75.8°; after 8 hrs. [α]D was 54°, after 24 hrs. treatment with a current of HCl, standing another 2 days under HCl pressure and again treating 5 hrs. with HCl it was 33°. The V, [α]678 118°, was obtained by Vavon’s method (Pd, either on charcoal or colloidal in gum arabic, instead of Pt gave a mixture of unchanged limonene and the di- and tetrahydro derivatives). VI, from V and 3% O2 in 4 parts AcOH (yield, more than 60%), b12 130-2°, d420 0.9393, [α]D20 -6.97°; semicarbazone, m. 182-3°. VII, from VI and cold aqueous KMnO4 (somewhat more than 1 atom O; yield, 75%), thick yellowish oil, b12 188°, dD20 1.020, [α]D20 2.5°, gives (+)-III with ice-cold NaOBr (6 atoms Br).
In some applications, this compound(610-09-3)Quality Control of cis-Cyclohexane-1,2-dicarboxylic acid is unique.If you want to know more details about this compound, you can contact with the author or consult more relevant literature.
Reference:
Benzisoxazole – Wikipedia,
Benzisoxazole – an overview | ScienceDirect Topics