Z-Tropic acid

The ease with which Z-hyoscyamine is racemized by alkali would suggest (235) that atropine is the intermediate in the hydrolysis of Z-hyoscyamine to tropine and dZ-tropic acid. If Z-hyoscyamine is hydrolyzed in water (60) tropine and Z-tropic acid are formed. From this it would appear that the optical activity of this Zeworotatory alkaloid may be attributed to the asymmetry of the tropic acid residue or that racemization of the tropine during hydrolysis has occurred. This last assumption apparently is not valid for all attempts to resolve tropine have failed (205). 

When heated with acids or alkalis, hyoscyamine undergoes hydrolysis into tropine and d -tropic acid probably via conversion into atropine, and it is this alkaloid which is hydrolysed. According to Gadamer, when hyoscyamine is hydrolysed with cold water the products are inactive tropine and Z-tropic acid. Amenomiya has shown that Ladenburg and Hundt s partially synthetic d- and Z-atropines were probably mixtures of atropine with d- and Z-hyoscyamines. He resolved ZZ-tropic acid into the d- and Z- forms, esterified these with tropine in 5 per cent, hydrochloric acid, and so obtained d- and Z-hyoscyamines, the latter identical with the natural alkaloid, d- and Z-Hyoscyamines have also been obtained by Barroweliff and Tutin by the resolution of atropine by means of d-eamphorsulphonie acid. 

Tropic acid crystallises in prisms and melts at 117°. It contains an asymmetric carbon atom and can be resolved into d- and Z-forms, which, according to King, melt at 128-9°, and have [ajj, + 81-6° and — 81-2° (HjO) respectively. 

When warmed with barium hydroxide, dilute alkalis or acids, hyoscin is hydrolysed, yielding tropic acid and a new base, CgHjsOjN, oscine o scopoline. Depending on the conditions of experiment, the tropic aci obtained may be either the pure Z-form or the partially racemised acid but the oscine obtained is invariably inactive. 

When Z-scopolamine (Z-hyoscine) is warmed with barium hydroxide (52, 56, 232), dilute alkalies (232), or acids (60, 212) it is hydrolyzed to tropic acid and a new base (CsHisOjN), scopoline (oscine). Depending on the conditions of the experiment, the tropic acid recovered may be either the pure Z-form or the partially racemized acid, or may even be dehydrated to atropic acid (52, 64, 232). The scopoline isolated from these experiments is invariably optically inactive (212). By analogy with Z-hyoscyamine, Z-scopolamine would appear to be a base (scopoline) in which the alcoholic... 

Castor oil is ctirrently the most important natural source of hydroxy fatty acids. The oil is derived from the seed of Ricinus communis, which grows as a perennial or annual in tropical and subtropical areas. Castor oil is the main source and contains 90% ricinoleic acid (12-hydroxy-9-Z-octadecenoic acid) [1]. This is a Cjg fatty acid with a Z-double bond between C-9 and C-10 and a hydroxyl group on C-12 (Fig. 1 (1-3). Castoroilwasfirstusedformedicinalpurposes, but over time, a wide... 

Fig. 13.6. DESI mass spectrum of Atropa belladonna seeds using methanol water =1 1 as spray solvent. The insets show tandem mass spectra of the protonated alkaloids hyoscamine, m/z 290 and scopolamine, m/z 304. Both protonated alkaloids have the characteristic loss of tropic acid, 166 u, in common. Reprinted from Ref. [13] with permission. The Royal Society of Chemistry, 2005.

It is probable that our ancestors of several million years ago developed the characteristics leading to our modem biochemistry by eating animal fats (Crawford and Marsh, 1989 Sinclair and O Dea, 1990 O Dea, 1991). At first glance this should simplify discussion of animal fats, as shown by the basic fatty acids of Table 10.1. A popular shorthand notation is used to indicate the stmctures of common fatty acids. In the format x yn-z, x is the chain length or number of carbons in the chain, y is the number of methylene-interrupted cis ethylenic bonds and z is the inclusive number of carbon atoms from the terminal methyl group to the center of the nearest bond. As few as six fatty acids appear to adequately describe animal depot fats. Those fats listed are dominated by two fatty acids, 16 0 (palmitic) and 18 1 (oleic) add. Although tropical seed oils may be rich in C12-C18 saturated fatty adds (Elson, 1992), temperate oilseeds are rich in oleic acid and tend to include quantities of two fatty acids more unsaturated than oleic, especially 18 2n-6 (linoleic), and sometimes 18 3n-3 (linolenic). Even the original rapeseed (Brassica sp.) oil, with up to 50% of 22 ln-9 (emdc) acid usually had approximately 20% 18 2/1-6 and 10% 18 3/i-3 adds (Ackman 1983, 1990). 

An important sulfide is methional (8-37). Methional in beer and wine is formed by the activity of microorganisms. It is partly reduced to the corresponding alcohol methionol (8-13) and reaction with acetyl-CoA yields 3-methylthiopropyl acetate (8-129), which is an important component of various fermented foods. Another ester of acetic acid 3-(methylthio)hexyl acetate is a component that posseses attractive tropical fruity notes on dilution. The less odoriferous (-)-(J )-enantiomer (8-130) is reminiscent of passion fruit, while the (-l-)-(S)-form has a more herbaceous odour. The odour thresholds of these thiols in air are 0.10 ng/1 and 0.03 ng/1, respectively. Both isomers have been found in passion fruit (Passiflora edulis, Passifloraceae), guava Psidium guajava, Myrtaceae) and aromatic white wines. Methyl-3-(methylthio)propionate, or pineapple mercaptan (8-131), has a flavour reminiscent of pineapple. S-Methylthiohexanoate (8-132) is a component of the durian fruit smell. Condensation of methional with ethanol yields (Z)-2-(methylthio)methylbut-2-enal also known as 2-ethylidenemethional (8-133), which is an important component of potato chips aroma. It also occurs in... 

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