摘要:

A method has been developed for the routine radiochemical analysis of technetium-99 in human urine. The excreted technetium is coprecipitated from a 200 mL urine sample with CuS. Valence state adjustments are performed with K2S2O8. The precipitate is dissolved in ammoniacal peroxide and, after the Cu(II) is removed by ion exchange, the Tc-99 is extracted with 2-butanone (MEK). Subsequent evaporation of the organic solvent gives an essentially weightless source that if counted with a gas proportional counter will give a better limit of detection than liquid scintillation methods. The recovery of Tc-99 using this procedure is 80% (σ = 4%) and the limit of detection is 20 mBq (0.6 pCi) at the 95% confidence level for a routine sample – counting time 20 minutes, counting efficiency 24%, ambient background 1.3 counts per minute (cpm).

ISSN:0008-4042    

DOI:10.1139/v83-335

出版商:NRC Research Press    

年代:1983

数据来源: NRC

摘要:

Rate constants,kq, for the quenching of the singlet state of benzene, toluene,p-xylene, fluorobenzene, trifluoromethyl benzene,p-bis(trifluoromethyl)benzene, and aniline by CCl4, CH3CCl3, CHCl3, and CFCl3, in the gas phase have been determined. In each instance the quenching is via a charge-transfer complex with the aromatic acting as donor. There is a linear dependence between lnkqand IP (ionization potential) of the aromatics which supports Klein's model for exciplex formation. The most effective quencher is CCl4while the least effective is CFCl3. The most effective donor was aniline while the least effective one wasp-bis(trifluoromethyl)benzene. In general, fluorinated aromatics are less effective donors than the corresponding protonated molecules.

ISSN:0008-4042    

DOI:10.1139/v83-336

出版商:NRC Research Press    

年代:1983

数据来源: NRC

摘要:

The reactions of the trisulfur trinitride anion, S3N3−, with halogens (Cl2, Br2, l2), AsF5, SOCl2, SO2Cl2, S2Cl2, COCl2, CS2, Me3SiCl, and Ph2PCl have been investigated. In all cases these reactions gave mixtures of known sulfur–nitrogen compounds. Thus the halogens react with S3N3−.to give mainly S4N4, S4N3+X−(X = Br, Cl), (SN)x, and S3N3X3(X = Cl), while AsF5oxidizes S3N3−to S4N4•AsF5. The major products of the reaction of S3N3−with SOCl2or SO2O2were S4N4, S4N3+Cl−, and (for SOCl2only) S3N2O2•S3N2Cl was the main product of the reaction of S3N3−with S2Cl2, whereas COCl2yielded (SN)xin addition to S3N2Cl and S4N4. Carbon disulfide reacts with S3N3−to give S4N2, S4N4, and CNS−. The cyclophosphathiazenes, (Ph2PN)(SN)2, 1,3- and 1,5-(Ph2PN)2(SN)2, in addition to (Ph2PN)x(x = 3, 4), (Ph2PN)3•HCl and (Ph2PN)2NSCl were isolated from the reactions of Ph2PCl with S3N3−in various molar ratios. The latter reaction represents a useful alternative synthesis of the 1,5-isomer of the eight-membered ring (Ph2PN)2(SN)2.

ISSN:0008-4042    

DOI:10.1139/v83-337

出版商:NRC Research Press    

年代:1983

数据来源: NRC

摘要:

An improved method for transforming certain coumarins to 2,2-dimethylchromencs has been developed. Umbelliferone (1b) was efficiently converted to precocene 1 (2b) (73%) by etherification to herniarin (1c) with tetramethylorthocarbonate, followed by reaction with methyllithium and cyclization of the resulting phenolic alcohol on silica gel.

ISSN:0008-4042    

DOI:10.1139/v83-338

出版商:NRC Research Press    

年代:1983

数据来源: NRC

摘要:

Irradiation of a sulfuric acid solution of 9,10-anthracenedione with near-uv light generated 2-hydroxy-9,10-anthracenedione as the major product. In addition, the 1-hydroxy and polyhydroxy derivatives and the reduction products anthrone and bianthronyl were also formed. The yields of these minor produets were markedly influenced by the concentrations of water and oxygen in the sulfuric acid. At low light intensities, oxygen quenched the efficient formation of the hydroxyanthracenediones and also oxidised the initial quinone reduction products. Photoreduction of the anthracenedione and photooxidation of anthrone occurred simultaneously in the solution. The reaction mechanism is more complex than previous studies indicated.

ISSN:0008-4042    

DOI:10.1139/v83-339

出版商:NRC Research Press    

年代:1983

数据来源: NRC

摘要:

We have studied the 184.9 nm photolysis of gaseous cyclohexene either in the absence or in the presence of radical scavengers such as O2, NO, H2S, or HI at pressures between 1 and 70 Torr. Propane or sulfur hexafluoride has also been used as stabilizing agent. In all cases, ethylene and 1,3-butadiene have rather high quantum yields (Ф ≥ 0.5). The isotopic analysis of the ethylene formed in the photolysis of cyclohexene-3,3,6,6-d4shows the high importance of the perhydrogenated species. These results, together with others taken from the literature, favor a one-step fragmentation mechanism or a double-step mechanism involving an intermediate which has a lifetime shorter than that of the photoexcited molecule

ISSN:0008-4042    

DOI:10.1139/v83-340

出版商:NRC Research Press    

年代:1983

数据来源: NRC

摘要:

Westphalen-type rearrangement of a 9α-hydroxy-11-ketone derived from lanosterol resulted in formation of two 19(10 → 9β)abeo-lanostenes representing the first lanostane-to-cucurbitane transformation. A novel ring A aromatic 9,10-seco derivative was formed as an acid catalysed cleavage product of 11-keto cucurbitenes. A cine 9 → 12 substitution led to the first 12-substituted lanostane derivatives and the first C-nor-D-homolanostane derivatives.

ISSN:0008-4042    

DOI:10.1139/v83-341

出版商:NRC Research Press    

年代:1983

数据来源: NRC

摘要:

The structures and charge distributions of Lewis and complexes of butane-2,3-dione,1, cyclohexane-1,2-dione,2, and 2-methoxycyclohex-2-en-1-one,5, have been investigated by1H nmr spectroscopy. A 1:1 complex was formed between1and SnCl4which appeared to have a bridged structure. In the case of2and5both oxygens were again involved in complex formation with TiCl4or SnCl4. In each case the large downfield shift of the vinyl proton resonance, H3, indicated extensive charge delocalization within the complexes and that these systems can be regarded as complexed α,β-unsaturated enones. The reactions of Lewis acid complexes of2,5, and the silyl ethers 2-(trimethylsiloxy)cyclohex-2-en-1-one, and 3-(trimethylsiloxy)-but-3-en-2-one,11, with butadiene have been investigated. The acyclic enol ether11reacted with butadiene in the presence of either TiCl4or SnCl4to give products corresponding to both 4C + 3C and 4C + 2C cycloaddition reactions; in all other cases 4C + 2C products only could be isolated.

ISSN:0008-4042    

DOI:10.1139/v83-342

出版商:NRC Research Press    

年代:1983

数据来源: NRC

摘要:

A general method for the generation of isobenzofuran intermediates is described. Lithiated aromatic acetals are converted to hydroxyacetals (A) which may be cyclized to isobenzofurans by mild acid treatment through the 1-hydroxyphthalans (B). The isobenzofurans generatedinsituare trapped by a variety of dienophiles to provide the expected oxo-bicyclo adducts (C). The mass and1Hmr spectra of B and C are discussed.

ISSN:0008-4042    

DOI:10.1139/v83-343

出版商:NRC Research Press    

年代:1983

数据来源: NRC

摘要:

A short synthesis of (±)-2-alkylthiocarbapen-2-em-3-carboxylic acid (2) from sorbic acid via a key intermediate4is described.

ISSN:0008-4042    

DOI:10.1139/v83-344

出版商:NRC Research Press    

年代:1983

数据来源: NRC