Thebaine, absorption

In situ quantitation The absorption photometric evaluation in reflectance was carried out at the wavelength k = 540 nm (Fig. 3). The detection limits in substance per chromatogram zone were 20 ng for thebaine and papaverine, 200 ng for codeine, 300 ng for morphine and 500 ng for narceine. 

Buprenorphine is a semi-synthetic derivative of thebaine, one of the opium alkaloids. It is approximately 30 times as potent as morphine. A dose of 0.3 mg intramuscularly has a duration of analgesic action of 6-18 h. Buprenorphine is also effective sublingually. The average bio-availability by this route is about 55%, but absorption is slow and the time to achieve peak plasma concentrations is variable, with a range of 90-360 min. The onset of action is rather slow (5-15 min) after both intramuscular and intravenous administration, possibly due to slow receptor association. Buprenorphine binds to and dissociates from the p receptor very slowly, which may account for its low potential for physical abuse. It also means that buprenorphine-induced respiratory depression is difficult to reverse with naloxone, even with very high doses. Doxapram may in these circumstances be useful. Drowsiness and dizziness are the most common side effects, although they rarely... 

Thermochemical studies have been made by Leroy [394-5], The absorption spectrum of codeine in the visible [396-7] and in the ultraviolet [398-9] has been determined. The ultra-violet absorption curve, compared with those of morphine and thebaine is given in Mg. 1. That of ethylmorphine is closely similar [400]. 

Thermochemical studies of thebaine have been made by Leroy [118-19]. The absorption spectrum of the alkaloid has been determined by Hartley [120] and the ultra-violet absorption spectrum (Eig. 4) by Girardet [121], Steiner [122], and Kitasato [123]. 

Dihydrothebaine- was originally given the structure [n], which was in accord with most of its chemical properties [3-4] except its failure to condense with benzoquinone or maleic anhydride and its failure to yield a derivative of 14-bromothebainone [iii] on treatment with bromine [5], However, the production of a conjugated diene as final product in a sodium-alcohol or sodium-ammonia reduction is contrary to general experience and examination of the infra-red and ultra-violet absorption spectra of dihydrothebaine-, thebaine, /3-dihydrothebaine, several 1 4-dihydroanisole derivatives, and 1-alkoxy-l 3-dienes led to modification of the structure of dihydrothebaine- to [iv] [6], which structure is more in accord with its properties than is [n], and in particular explains why the hydrogenation of this base proceeds with absorption of only one mole of hydrogen (see Chap. XIV). 

Examination of the infra-red and ultra-violet absorption spectrum of /3-dihydrothebaine indicated that it has in fact the structure [n] initially allotted to dihydrothebaine- [6]. Such a conjugated diene would be expected to imdergo 1 4-addition of hydrogen with final production of [vm], a reduction parallel to the production of tetrahydrothebaine from thebaine (see below). 

Reduction of the orange-red solution of thebaine in concentrated hydrochloric acid with zinc affords a yellow phenolic base about which little is yet known beyond the facts that it is dimolecular and contains no carbonyl group. Its ultra-violet absorption spectrum contains a band at about 3,800 A, apparently indicating the presence of a highly conjugated system of double bonds such as... 

This isomer is obtained in erratic yield by the hydrolysis of dihydro-thebaine- by sulphurous acid. It was initially allotted the structure [xm] [3], but has since been shown to have the structure [xxv], which is allotted to the base on account of the ultra-violet absorption spectrum, which indicates a highly conjugated system (Figs. 8 and 9), and the infra-red absorption, which indicates that the compound is a /3 y-unsaturated ketone [13]. It is apparently formed during the hydrolysis... 

Catalytic hydrogenation of thebaine-quinone over platinum oxide in glacial acetic acid proceeds with the rapid absorption of one mole of hydrogen and the somewhat slower absorption of a second mole to give tetrahydro-thebaine-quinone [xvm]. If the reduction is stopped after the first mole of hydrogen has been absorbed, a product that is probably mainly [xix] is obtained it is believed to be mainly [xrx] as mainly non-phenolic matter is obtained after one minute s boiling with concentrated acid, under which conditions [xvi] is isomerized to [xvh] [3]. Attempted demethylation of [xvni] with hydriodic acid affords only tars [3]. 

Fig. 154). In the quantitative determination, the spots were scraped off the plate [silica gel G (Merck)], eluted with methanol, the eluate made up to 5 ml and the concentration of alkaloid determined from the light absorption (wave lengths used were narcotine 312 nm, morphine 286 nm, thebaine 285 nm, papaverine 279 nm and codeine 215 nm). Steele [230 b] has recently achieved good separations of opiates in narcotic seizures, using silica gel G layers. The i /-values of 26 compounds were evaluated in eight solvents the best solvents were found to be ethyl acetate-benzene-acetonitrile-ammonium hydroxide (50 + 30+ 15 + 5) and acetonitrile-benzene-ethyl acetate-ammonium hydroxide (40 + 30 +25 + 5).. ...

Fig. 36.4 Chemical structures of morphine (M), codeine (C), oripavine (O), thebaine (T), and pseudomorphine (P) and their separation by cyclodextrin-modified CZE using different CDs. Conditions (a) HP-PCD, (b) yCD, (c) pCD, and (d) aCD. Buffer 100 mM Tris-phosphate, pH 2.8 CD concentration of 30 mM except for pCD (10 mM due to limited solubility) applied voltage of 25 kV 2 s injection at 50 mbar 20 °C capillary 50 cm x 50 pm i.d. UV absorption detection at 214 nm (Modified from ref. [47])...

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