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The method of Gaitonde and Dovey [Biochem. J.117, 907 (1970)] for the determination of tryptophan by reaction with ninhydrin in acid is adapted for the measurement of protein bound to solid support materials, including collagen. DEAE-Sephadex, DEAE-cellulose, polyacrylamide and collodion give negligible background absorbance with the reagent; collagen and activated agarose give some color, but this can be abolished by pretreating the collagen with H2O2. Collagen, Sephadex and agarose dissolve in the reagent. Levels of lactase (β-galactosidase) and glucoamylase were readily and linearly measured down to 0.2 mg in the presence of 21 mg collagen, and activity and immobilized protein content of lactase-collagen complexes were linearly related.

TBP has been used for the extraction of palladium(II) from hydrobromic acid medium and a simple extraction scheme developed for separation of palladium from Fe(III), Co(II), Ni(II), Ru(III), Rh(III), Ir(III), and Pt(IV). A spectrophotometric method is described for the determination of palladium with 1-phenyl-2-thiourea. The effects due to acidity, solvents, reagent concentration and diverse ions are reported. The complex is probably of 1 ∶ 1 composition.

The Karl Fischer reagent reacts with many low valent transition metal complexes to bring about oxidation of the metal. The reaction can be used for the oxidimetric determination of these complexes in solution and must be taken into account when PIII ligands are determined in low valent metal complexes.

Silver carbonate on Celite (the Fetizon reagent) was shown to be selective as an oxidizing agent, and convenient for the preparation of various aldonolactones. Whereas substituted aldoses having the 1-hydroxyl group free were readily converted into the corresponding lactones, partially protected 2-acetamido-2-deoxypyranoses having more than one free hydroxyl group were selectively oxidized at C-1. The oxidation was carrried out in boiling benzene or 1,4-dioxane. A series of partially protected 2-acetamido-2-deoxy-1,5-aldonolactones [2-acetamido-4,6- O -benzylidene-2-deoxy- D -mannono-1,5-lactone ( 13 ),2-acetamido-4,6- O -benzylidene-2-deoxy- D -glucono-1,5-lactone ( 15 ), 2-acetamido-2-deoxy-4,6- O -isopropylidene- D -glucono-1,5-lactone ( 18 ), 2-acetamido-2-deoxy-4,6- O -isopropylidene- D -mannono-1,5-lactone ( 20 ), 2-acetamido-2-deoxy-3,4-di- O -methyl- D -mannono-1,5-lactone ( 24 ), and 2-acetamido-2-deoxy-3,4-di- O -methyl- D -glucono-1,5-lactone ( 25 )] was thus prepared; for these, the oxidation was accompanied by two side-reactions: ( a ) an elimination (dehydration) that gave the unsaturated lactones [2-acetamido-4,6- O -benzylidene-2,3-dideoxy- D - erythro -hex-2-enono-1,5-lactone ( 12 ), 2-acetamido-2,3-dideoxy-4,6- O -isopropylidene- D - erythro -hex-2-enono-1,5-lactone ( 17 ), and 2-acetamido-2,3-dideoxy-4- O -methyl- D - erythro -hex-2-enono-1,5-lactone ( 23 )], and ( b ) partial gluco -to- manno epimerization occurring during the oxidation of 2-acetamido-4,6- O -benzylidene-2-deoxy- D -glucopyranose ( 14 ), 2-acetamido-2-deoxy-4,6- O -isopropylidene- D -glucopyranose ( 16 ), and 2-acetamido-2-deoxy-3,4-di- O -methyl- D -glucopyranose ( 22 ). The free unsaturated lactone, 2-acetamido-2,3-dideoxy- D - erythro -hex-2-enono-1,5-lactone ( 26 ), was obtained on hydrolysis of the isopropylidene group in lactone 17 .

35 S-Labeled dithio-bis(2-nitrobenzoate) has been prepared and its usefulness for the measurement of protein sulfhydryl groups has been investigated. The technique is at least 20 times more sensitive than when dithio-bis(2-nitrobenzoate) is used colorimetrically. The adduct formed between the reagent and sulfhydryl groups is stable between pH 3–9 which should enable use of the reagent for the tagging of sulfhydryl-containing proteins in a wide variety of biochemical procedures. Removal of the adduct from a protein is achieved simply by treatment with a thiol reagent, with concomitant restoration of enzymic activity of the protein. The procedure has been successfully tested on alcohol dehydrogenase and mammalian ribosomes.

It was found that common ketones were prepared in good yields by the reaction of grignard reagents with mixed carboxylic anhydrides composed of o-substituted benzoic acids or pivalic acid and commo...

Quinalizarin reacts very sensitively with molybdenum and uranium to form colored chelates having λmax at 520 and 630 nm, respectively. The molar ratio for both the chelates is 1:1 (metal:reagent). Optimum conditions including the range for adherence to Beer's law, effect of pH on color intensity, effect of excess of the reagent, sensitvity, and interference of the foreign ions has been reported for the photometric determination of these metal ions using quinalizarin, in 50% ethanolic medium and at 30 °C.

The quinuclidine ring in the reaction of 2-ethoxycarbonyl-3-oxoquinuclidine with nucleophilic reagents under mild conditions is cleaved at the C2-C3 bond to give 1-carboxymethylisonipecotic acid and its derivatives.

Reduction of methyl 4,6-O-benzylidene-α- and β-d-glycopyranosidulose derivatives with sodium borohydride was carried out. From the yield of the axial and equatorial epimers, a possible mechanism of the borohydride reduction and factors determining the directions of the reagent’s attack to a carbonyl group are discussed.

Biogenetic oxidations of α-pinene along three different routes in Scheme 1 were conducted in vitro, and the activities of the oxidation products in attraction of the pine beetle, Cryphalus fulvus, were compared in field tests. Oxidation with selenium dioxide along route A in Scheme 1, resulting in production of myrtenal and myrtenol, revealed increased activity compared to that of the parent hydrocarbon. A greater increase of activity was observed when β-pinene was oxidized with the same reagent. Detection of myrtenal and myrtenol in host volatiles revealed their contribution to host attraction, but the presence or absence of pinocarvone and trans-pinocarveol in the host remained uncertain.

Two synthetic routes to compounds of the type π-Cp 2 Ti III R (R=CH 3 , CH 2 Si(CH 3 ) 3 , C 6 F 5 ) have been investigated: (a) chemical reduction of π-Cp 2 Ti IV (R)Cl by zinc or aluminum metal in tetrahydrofuran, and (b) conventional organometallic syntheses using organo-lithium or -magnesium reagents and [π-Cp 2 Ti III Cl] 2 . The preferred route is via an organolithium reagent, since chemical reduction gives a mixture of products. Green, monomeric complexes (R = CH 2 Si(CH 3 ) 3 , C 6 F 5 ) were isolated and characterised. From the reaction of π-Cp 2 Ti IV Cl 2 and trimethylsilylmethyllithium in a 1/1 ratio, π-CpTi IV [CH 2 Si(CH 3 ) 3 ] 3 was obtained. Unlike π-Cp 2 Ti III C 6 F 5 , π-Cp 2 Ti III CH 2 Si(CH 3 ) 3 does not form a blue complex with molecular nitrogen.

The synthesis of the new rhenium nitrosyls Re(CO)2 (NO)(PPh3)2 and Re(H)(NO)2 (PPh3)2, and the reactions of these low-oxidation state complexes with reagents such as X2 (X = Cl, Br, I) and RX (X = halogen; R = H, CH3, CH3 CO, C6H5CO) are described. The products include some new rhenium halonitrosyl derivatives.

A quantitative determination by a simple detection system for carbohydrates with elution chromatography was developed. This method depends upon the detection of ultraviolet absorbing chromophere, with absorption maximum in the 260-270 mμ region, produced by heating the carbohydrates in the eluent solution without reagent. In the product from fructose, the existence of furfural and formic acid was confirmed . The heating condition and eluant buffer (conc., pH) affected the intensity of ultraviolet absorption produced. Under the condition of heating below 190°C and shorter than 20 min, the greater efficiency was obtained at higher temperature and longer period . Higher concentration and neutral pH of borate buffer were more effective . The molar absorption coefficient at 260 mp of mono- and oligosaccharides heated in a solution of 0.8 M borate buffer pH 7.0 for 9.5 min at 190°C was 500-3000 . The coefficient of variation of this method was less than 3.5%. A heating period was obtained by adjusting the diameter and length of teflon tube connected with the chromatographic column. In order to decrease the extra column effect, it was effective to decrease the diameter of tube (0.5 mm) and heating period, and increase the heating temperature . Several examples for mono- and oligosaccharides and oligodextrines were shown.

6′- O -Trityl-α-maltose heptaacetate ( 1 ) was prepared by detritylation of 6,6′di- O -trityl-α-maltose hexaacetate ( 5 ) with 80% acetic acid at 100°, followed by retritylation with an equimolar ratio of reagent, and subsequent acetylation. When 5 was prepared by tritylation of maltose with a 3-molar equivalent of reagent followed by acetylation, the β- D anomer ( 6 ), of 5 was also isolated. A mixture of the six possible 6- and 6′-mono-, and 6,6′-di- O -tritylmaltose peracetates was obtained by direct tritylation of maltose with a 1:1 molar ratio of reagent and subsequent acetylation. All six products were isolated by chromatography on silica gel and by precise fractional crystallization; the yields of each were very different. The main product was 6′- O -trityl-β-maltose heptaacetate ( 2 ). The isomers having the trityl group on the nonreducing residue were much more dextrorotatory than those having the trityl group on the reducing residue. Studies on the molecular rotations suggested that changes in conformation at the glycosidic linkage, as expressed in torsional angles about the C—O and O—C bonds, may influence the magnitude of the optical rotations of these compounds. All of the six trityl derivatives gave positive, plain o.r.d. curves. An analog of 6′- O -trityl-α-maltose heptaacetate ( 1 ) having a trideuterioacetyl group at C-6, and an analog of 6- O -trityl-α-maltose heptaacetate ( 3 ) having a trideuterioacetyl group at C-6′, were synthesized to permit assignments of the 6-acetoxyl group signal in the n.m.r. spectrum of 1 and the 6′-acetoxyl group signal in the n.m.r. spectrum of 3 . The discrepancy in the chemical shifts of these acetyl methyl protons substantiated the foregoing postulates based on optical rotation.

Both cis - and trans -crotyltrimethyltin react with n-butyl- and methyllithium in ether to give crotyllithium in high yield. In each case, reaction of the reagent solution with trimethylchlorosilane gives an approximately 3 2 mixture of trans - and cis -crotyltrimethylsilane. These transmetalation equilibria permit the isomerization of cis - and trans -crotyltrimethyltin to a 3 2 trans / cis mixture by small amounts of n-butyl- or methyllithium. Metallic lithium also causes isomerization of the cis - and trans -crotyllithium isomers via a metal displacement process which generates a small amount of crotyllithium which is capable of exchanging crotyl groups with unconverted crotyltrimethyltin. The possible mechanism of the isomerization reactions observed is discussed.

The stereochemistry of β-fragmentation products formed in the oxidation of cis-and trans-4-t-butylcyclohexaanemethanol with lead tetraacetate and with lead tetraacetate-metal chloride combinations, under various reaction conditions, has been investigated, and the results compared with those obtained, under similar conditions, in the oxidative decarboxylation of cis-and trans-4-t-butylcyclohexanecarboxylic acid with the same reagents. It was found that all four substrates afford, under comparable conditions, identical cis-trans proportions of the respective fragmentation products, and that, therefore, so far as steric course is concerned, both the initial homolytic and subsequent heterolytic processes involved in the lead tetraacetate fragmentation reaction are independent of the nature and configuration of the starting material.

The radical anion of sodium 9,10-anthraquinone-2-sulfonate, which was produced by the photolysis of the quinone in aerobic aqueous solution (pH 8.0) containing appropriate amounts of anionic and/or non-ionic surfactants, was detected by means of ESR and UV spectroscopy. The formation of the radical anion was observed above pH 6.8. Relationship between the concentration of surfactant and that of the radical anion gave a profile which showed the typical micellar effects. It is suggested that the micelles protect the radical anion from quenchers, such as oxygen, water, and other reagents, because the radical anion is incorporated into the micellar interior.

Summary The best reagent for displacing adsorbed NH, for the measurement of cation exchange capacity of soils is a mixed ZN nitrate solution of potassium and calcium. The equivalent ratio of K to Ca should be in the range from 1 to 3. This mixture is better than simple solutions of Li, Na, K, Mg, Ca, Sr, and Ba nitrates and mixtures of KNO3 with any one or two of these other nitrates.

Lithium phosphoramides are fairly unreactive with respect to alkylating agents. Their action is shown by the formation of a β-lithium amide. This bimetallic structure undergoes either bisalkylation or cyclisation according to experimental conditions; a cyclic intermediate is postulated to account for these observations.

The published methods for fluorometric determination of Se in plants are reviewed, with particular attention to those using 2,3-diaminonaphthalene as the fluorometric reagent. Two steps in the analysis are shown to be critical: the final stages of the digestion and the complete conversion of the Se to Se(IV). A modified experimental procedure is given.

La combinaison de l'etude directe des spectres de RMN du proton et des deplacements induits par le complexe Eu(fod)3 a permis d'etudier les phenomenes d'isomerie syn-anti (Z-E) dans un certain nombre d'imines cycliques et acycliques. Un cas d'equilibration syn ⇌ anti par addition d'Eu(fod)3 a pu etre mis en evidence. Analysis of NMR spectra of different cyclic and acyclic imines, together with those obtained with the lanthanide shift reagent Eu(fod)3, allowed the characterisation of the syn-anti (Z-E) isomerism of these compounds. In one case, it was possible to demonstrate a syn-anti equilibration by adding Eu(fod)3.

Replacement of a carbonyl ligand by a PPh 3 ligand stabilizes isolable σ-propargylic compounds of molybdenum. By consecutive reaction with some nucleophilic reagents π-allyl derivatives are obtained.

Crystals of human carbonic anhydrase C were reacted with [14C] bromoacetazolamide and an alkylation was found to occur at the 3′-nitrogen of histidine-64, which is known to be located in the active site region. This reaction requires that the bromomethyl group of the reagent move from its initial binding position, phenylalanine-129, within bonding distance of histidine-64 without significantly disturbing the interaction of the sulfonamide moiety with the active site zinc ion. Since the same histidine has been found previously to react with bromoacetazolamide when the enzyme was in solution, it can be concluded that the conformation of the active site histidine is the same in the two states.

2,3,4,5-Tetrahydro-benzo[b]thiepin-5-one, its 7-methyl derivative, and their S, S-dioxides condense with aromatic aldehydes to give the corresponding 4-arylidene derivatives 3 and 4. Compounds 4 react with hydrazine and phenylhydrazine to yield 3, 3a, 4, 5-tetrahydro-2 H-benzo-[b]thiepino[4, 5-c]pyrazole S, S-dioxide derivatives 5 and 6. Some of the arylidene derivatives 4 add GRIGNARD reagents to give 7. The IR spectra of representative examples are discussed.

The phase transition in the firing of compositions based on the system Mg(Al1−XCrX)2O4-(Fe2O3, SiO2) consist essentially of the formation of solid solutions of spinels and the ferrous component of the reagent, and the solution of the spinel in the iron-silica melt.

The use of 1,3-dichloro-1,1,3,3-tetrafluoroacetone for derivatization of α-amino acids offers two important advantages. Firstly, the amino group, which is coupled with the carboxylic group in a five membered ring, does not require further treatment with an anhydride or silyl reagent and, secondly, the next reaction step, the esterification of the remaining protonic groups, can be performed immediately after the first reaction without evaporation of the reaction medium. Moreover, the oxazolidinones show very good chromatographic properties and a high response to the electron capture detector (ECD) comparable with that of lindane. The response to the flame ionization detector (FID) is nearly the same as that of trifluoroacetylated methyl esters of amino acids. The oxazolidinones of tyrosine and mono- and diiodotyrosines were prepared and, after treatment with acetic, trifluoroacetic, heptafluorobutyric or pivalic anhydride or with hexamethyldisilazane, they were chromatographed on silicone phases. The relative molar responses to hexadecane (FID) and lindane (ECD) were determined.

Brief exposure of rat bone matrix to highly charged electrochemicals had profound but reversible effects on its competence to transform fibroblasts into chondroblasts and osteoblasts. Suppression and subsequent reactivation of this function were influenced critically by the charge of the electrochemical reagent and the pH of the reaction mixture. In dilute acids, Evans Blue, a long electronegative molecule, suppressed transforming competence, whereas hexadimethrine, a polycationic quaternary ammonium base, failed to do so. A cycle of inactivation-restoration of transforming competence was achieved by sequential treatment of bone matrix with Evans Blue followed by hexadimethrine; an electrochemical complex was demonstrated by histochemistry. In dilute alkalies, hexadimethrine inhibited, whereas, Evans Blue did not suppress the transforming function of the bone matrix. Electric charge characteristics on the surface of the bone matrix are of crucial significance for the fibroblast-transforming attribute.

The reduction of alkylidenemalononitriles by Cervinka's reagent (LiAlH 4 complexes of chiral amino alcohols) yields the same asymmetric induction as the reduction of ketones. But the reduction by these same reagents of the Z and E isomers of alkylidenecyanoacetic esters gives opposite induction. These last results suggest the formation of an intermediate complex between the electrophilic reagent, the hydride and the chiral amino alcohol. ab]La reduction de l'alcoylidene malononitrile par les reactifs LiAlH 4 /aminoalcools chiraux suit la correlation empirique etablie par Cervinka pour la reduction des cetones. L'induction asymetrique de sens oppose obtenue pour la reduction des deux isomeres Z et E de l'alcoylidene cyanacetate indique une complexation entre l'hydrure et le reactif electrophile.

The kinetic study of monomolecular or pseudomonomolecular reactions is easily followed by microcalorimetry and the analysis of the thermograms is straight-forward. We describe the conductimetric and calorimetric study of the hydrolysis of ethyl chloroformiate. Measurements at various temperatures in different water—dioxane mixtures yield the thermodynamic data of the reaction. For ethanolysis of benzoyl chloride, the thermokinetic measurements are the only ones which give good results, because the hydrochloric acid which is released during the reaction is a weak electrolyte in non-aqueous media.

Summary Alkyltin trialkoxides, RSn(OR′)3 (R = Et, n-Bu and R′= CH3, C2H5, i-C3H7, n-C4H9 and t-C4H9) have been synthesised from alkyltin trichlorides and the corresponding sodium alkoxide. Mixed derivatives of the type BuSnXn(OPr-i)3 (X = Cl, CH3CO2 and C2H5CO2) were obtained by exchange reactions. Reactions of butyltin triisopropoxide with protic reagents (e.g., H2O, (CH3)2C=NOH, o-HOC6H4OH, C6H5CH2NH2, NH2CH2CH2NH2, i-PrNHCOCH3, n-BuNHCOCH3, HCONH2 and CH3CONH2) have been studied. Dialkyltin acetamido derivatives have also been synthesised. IR and NMR spectra and molecular weights of the new products are reported and discussed.

A systematic 3D classical-trajectory study has been made of the effect of reagent energy distribution and mass combination on the dynamics of endothermic reaction. The potential-energy hypersurface was endothermic by 35.7 kcal mole−1. Reagent translation, T′, and vibration, V′, was varied in the range up to T′ + V′ = 90 kcal mole−. Among the principal findings for the equal-mass case were the following. (i) There is an orders-of-magnitude increase in reaction cross section when energy is transferred from T′ to V′, until an optimal distribution over T′ and V′ is achieved at V′ ⪖, T′. There is a qualitative difference between the forms of the reactive cross section dependences S(T′) V′ and S(V′)T′. (ii) The greater efficacy of V′ than T′ in promoting endothermic reaction is marked even at total reagent energies ≈ 3 x the endothermic barrier height. (iii) The total reactive cross section for endothermic reaction increases to large values (≈ gas kinetic) as V′ increased to several times the barrier height. (iv) Reagent energy in excess of that required to cross the endothermic barrier is subject to the same “adiabatic” transformation into product energy as was previously observed for exothermic reactions: ΔT′ → ΔT + ΔR (where R is enhanced product rotational energy), and ΔV′ → ΔV. This is explained in terms of induced repulsive energy release in the former case, and induced attractive energy release in the latter. (v) The molecular product is backwards or sideways scattered. Enhanced V′ at constant T′ diminishes product repulsion, giving rise to more-forward scattering. (vi) These findings remain qualitatively unchanged when extreme mass combinations H H + L and L H + H (L = 1 amu, H = 80 amu) are substituted for the equal-mass combination, L L + L. Effects ascribable to a “late” barrier are accentuated for HH + L. and diminished for L H + H. (vii) The total reactive cross section at a given reagent energy increases in the sequence H H + L, L L + L, L H + H, for simple kinematic reasons. (viii) The dynamics on this endothermic potential-energy surface resemble, in all the points listed above, the dynamics on a thermoneutral surface which has its barrier crest in the coordinate of separation (surface II of part I of this series).

When rapid gas-liquid chromatography methods for determination of bacterial fatty acids were compared, results showed that saponification was required for total fatty acid analysis. Transesterification with boron-trihalide reagents (BF 3 -CH 3 OH, BCl 3 -CH 3 OH) caused extensive degradation of cyclopropane acids and was less effective than saponification in releasing cellular hydroxy fatty acids. Digestion of cells with tetramethylammonium hydroxide was unsatisfactory because of extraneous gas-liquid chromatography peaks and because of lower recovery of branched-chain and hydroxy fatty acids. A simple, rapid saponification procedure which can be used for total cellular fatty acid analysis of freshly grown cells is described.

Pro-tRNA synthetase from D. regia and P. aureus lost enzymic activity more rapidly at 0° than at room temperature. The enzyme from a number of higher plants that produce azetidine-2-carboxylic acid (A2C) was more rapidly inactivated in the cold than the enzyme from plants which do not contain A2C. The rate of cold inactivation was dependent on temperature and on the concentration of glycerol, protein and sulphydryl-reducing reagents. Substrates of Pro-tRNA synthetase also stabilized the enzyme against cold inactivation. Enzyme which had been completely inactivated by storage in the cold, could be reactivated by warming in the presence of a sulphydryl-reducing reagent. The rate of reactivation was dependent on temperature, pH and the concentration of sulphydryl-reducing reagent. Kinetic analysis indicated the existence of more than one molecular form of the enzyme. It is suggested that the cold-lability of Pro-tRNA synthetase may be due to dissociation of the active enzyme molecule into inactive subunits.

An enzymatic method is described for determination of total serum cholesterol by use of a single aqueous reagent. The method requires no prior treatment of sample and the calibration curve is linear to 600 mg/dl. Cholesterol esters are hydrolyzed to free cholesterol by cholesterol ester hydrolase (EC 3.1.1.13). The free cholesterol produced is oxidized by cholesterol oxidase to cholest-4-en-3-one with the simultaneous production of hydrogen peroxide, which oxidatively couples with 4-aminoantipyrine and phenol in the presence of peroxidase to yield a chromogen with maximum absorption at 500 nm. The method is reproducible, and the results correlate well with those obtained by automated Liebermann—Burchard procedures (AA-2 and SMA 12/60) and the method of Abell et al. The present method affords better specificity than those previously reported and has excellent precision.

The conditions for sorption and elution of neptunium(IV) from nitric acid solutions on zirconiumphosphosilicate (ZPS) have been examined in batch and column experiments. Batch experiments have indicated that the fixation depends strongly on the acid concentration. The separation of Pu and Np can be performed on ZPS by a selective reduction of Pu(III) and Np(IV), respectively, with Fe(II) sulphamate in 0·35 M HNO 3 . Only Np(IV) is retained on the ZPS column and can be eluted with 8·0 M HNO 3 .

Malic enzyme of pigeon liver (l-malate:NADP+ oxidoreductase (decarboxylating) EC 1.1.1.40) contains a total of approximately 10 —SH groups per subunit, reactive with 5,5'-dithiobis(2-nitrobenzoic acid) (DTNB). Two or more exposed groups (Class I) are highly reactive with DTNB; alteration of these groups does not impair the oxidative decarboxylase activity. This activity, however, is lost upon reaction of a less accessible —SH group (Class II), the alteration of which also results in concomitant increase in the ability of this enzyme to reduce pyruvate in the presence of NADPH. The remaining —SH groups (Class III) in the undenatured enzyme are largely unreactive with this reagent. The alkylating reagent N-ethylmaleimide (NEM) induced similar changes in the over-all and reductase activities of this enzyme. These effects by NEM are also attributed to the alteration of Class II —SH group, since they are prevented by reversible attachment of a thionitrobenzoate substituent (from DTNB) to this —SH group prior to reaction with NEM. Modification of Class II —SH group by either reagent is promoted by carboxylic acid substrates, and partially prevented by Mn2+. This group appears to be located at or near the active center of this enzyme, but is not directly involved in the binding of reactants nor in the catalytic process. An —SCN derivative was prepared by reacting the DTNB-modified enzyme with KCN. This derivative was found to be completely active in oxidative decarboxylation. Apparently, the geometry of the active center is such that this activity is impaired by the attachment of a relatively bulky or charged substituent to the Class II —SH group. Furthermore, our experimental data implicate that modification results in the blockage of the reversible C—C bond cleavage step, thereby accounting for the loss of oxidative decarboxylase and decarboxylase activities.

The reaction of vinyllithium with (CO) 5 CrC(OCH 3 )C 6 H 5 (Ic) at−78° followed by the treatment with HCl at −78° gave 43% ( Z )-1-methoxy-1-phenylpropene (IIIa) and 21% 1,4-dimethoxy-1,4-diphenyl-1,3-butadiene (IVa) and no trace of a vinylphenylcarbene complex or its expected decomposition products. IIIa and IVa are proposed to arise from electrophilic attack at the carbon-carbon double bond of a σ-allychromium intermediate. The reaction of phenyllithium with (CO) 5 CrC(OCH 3 )CH=CHC 6 H 5 (V) gave 9% (CO) 5 CrC(OCH 3 )CH 2 CH- (C 6 H 5 ) 2 (VI) and 17% ( E )-1-methoxy-1,3-diphenylpropene (VII). Reaction of V with lithium diphenylcuprate gave 30% of the conjugate addition product VI.

The chemical ionisation mass spectra of a number of representative explosives have been obtained using hydrogen as reagent gas. Fragmentation modes of the protonated molecular ions tend to be simple although some rearrangements have been noted. Loss of a radical from an even electron parent ion has been observed. The use of ‘ghost spectra’ for confirmation of the molecular weight of the sample is stressed: these consist of ions of low abundance resulting from reactions between sample ions and sample molecules. Labelling studies were carried out using deuterium as reagent gas.

Metabolism of 3, 5-dimethylphenyl N-methylcarbamate (Cosban) was examined. Cosban was administered to rabbits during 1 week and urine was collected and extracted daily. From the ether extract under acidic condition, 5-hydroxytoluic acid and (3-carboxy-5-methyl) phenyl N-methylcarbamate were isolated and identified with authentic samples by mixed melting point determination, and infrared and nuclear magnetic resonance spectra. 3, 5-Dimethylphenol was detected by thin-layer chromatography (TLC) and gas chromatography. The aqueous layer left after ether extraction was extracted with a mixed solvent of ether and ethanol (2 : 1) and, from this extract, glucuronides of both 5-hydroxytoluic acid and 3, 5-dimethylphenol, and sulfate of 3, 5-dimethylphenol were obtained. To 100 ml of human urine, 1 mg each of Cosban, (3-carboxy-5-methyl) phenyl N-methylcarbamate, 5-hydroxytoluic acid, and 3, 5-dimethylphenol were added and the mixture was kept overnight. These substances were well separated and detected by silica gel TLC using a developing solvent of hexane-ethyl acetate-formic acid (75 : 25 : 5) and a coloration reagent of 2, 6-dibromoquinone chloroimide.

Bei den Umsetzungen von (CO)5CrC(OCH3)CHR1R2 (R1 = H, R2 = H, CH3, C2H5 und R1 = R2 = CH3) 1–4 mit verschiedenen tertiaren Stickstoffbasen wurden in guten Ausbeuten Enolather vom Typ CH3OCHCR1R2 erhalten. Diese Beobachtungen werden durch die Spaltung der Chrom-Carbenkohlenstoff-Bindung durch das freie Elektronenpaar des Stickstoffs der Base und eine 1,2-Wasserstoffverschiebung eines zum Carbenkohlenstoff-Atom α-standigen H-Atoms verstandlich. Da die entsprechenden Umsetzungen mit p-Dioxan und 1-Methyl-2-pyrrolidon keine eindeutigen Reaktionsprodukte ergeben, hangt diese 1,2-H-Verschiebung offenbar masgeblich von der Basizitat des Reagens ab. Dagegen gab die thermische Abspaltung des Carbenliganden in Decalin das Dimere des Carbenliganden. Transition Metal Carbene Complexes, LXXVII. Cleavage of the Carbene Ligands from Pentacarbonyl(methoxyalkylcarbene)chromium(0) Complexes in some Tertiary Nitrogen Bases, p-Dioxan and Decalin (CO)5CrC(OCH3)CHR1R2 (R1 = H, R2 = H, CH3, C2H5, C2H5, and R1 = R2 = CH3) 1 — 4 reacts with various tertiary nitrogen bases to give enolethers of the type CH3OCHCR1 R2 in good yields. An explanation for these observations is the cleavage of the chromium-carbene-C-bond by the lone electron pair of the nitrogen base and a 1,2-shift of an H-atom in an α-position to the carbene C-atom. Analogous reactions with p-dioxan and 1-methyl-2-pyrrolidone give no definite products. Therefore the 1,2-H-shift seems to depend on the basicity of the reagent. On the other hand the thermal cleavage of the carbene ligand in decalin gave the dimer of the carbene ligand.

Basic phenomena of H+and H− ion concentration process are considered, and state apace models are derived for a basic continuous flow system. Inherent non-linearity of the system can he avoided by a change of variables, hut due to the logarithmic measurement via pH the corresponding feedback control system is highly nonlinear. A basic feedback system is proved to be globally asymptotically stable. Through an augmentation of the basic model it is shown that a relatively small non-ideality in a real system is sufficient to make it unstable. On the other hand, a steady state analysis show that the concentration equilibrium is highly sensitive to deviations of parameters related to the controlling chemical reagent, if a concentrated acid or base is being neutralized in a single stage.

Experimental data concerning the effect of varying reagent vibrational, rotational and translational energy on the rates of endothermic reactions can be obtained from the application of microscopic reversibility to the corresponding exothermic processes. A 3D classical trajectory computation has been performed to test this procedure. On the basis of this study we conclude that the ‘triangle plots’ of endothermic detailed rate constants published previously can be depended on to 5–10% theoretical accuracy (expressed as a percentage of the maximum endothermic rate constant).

In several synthetic problems in our laboratory it became essential to react a basic nitrogen atom with a suitable protecting group which could be subsequently removed under very mild conditions. The presence of sensitive functionality elsewhere in the molecule prevented serious consideration of most of the reagents which have been developed for dealkylation of quaternary ammonium salts2–12. One of the most recent methods involving the highly nucleophilic system, lithium n-propylmercaptide in hexamethylphosphoramide12 (HMPA) was thought to be most desirable but even in this instance demethylation of the quaternary system provided difficulties. For example, demethylation of the methiodide derivative of 18β-carbomethoxycleavamine (II, R [dbnd] CH3, 3,4-double bond) provided only a 5% yield of the desired product. It was clear that a protecting group more susceptible to nucleophilic displacement was essential. During our studies directed to this end it has been established that the benzyl group sati...

Citrate synthase of wheat (Triticum aestivum L.), bean (Phaseolus vulgaris L.), cauliflower (Brassica oleracea L.), and a marine blue-green alga (Coccochloris elabens) is inhibited by sulfhydryl binding reagents. The inhibitions are partially reversed by dithiothreitol. Pig heart citrate synthase is only slightly inhibited by the same reagents and this is completely reversed by dithiothreitol. All citrate synthases in this study are inhibited by adenosine triphosphate. The inhibition is relieved by increasing the concentration of acetyl coenzyme A. Citrate synthase of wheat, cauliflower, bean, and pig heart was estimated by gel filtration to have a molecular weight of 100,000 daltons. The Coccochloris citrate synthase was estimated to have a molecular weight greater than 250,000 daltons. The evolutionary implications of these findings are discussed. This enzyme is comparable in size to the 100,000 dalton mammalian enzyme (Singh et al. 1970) making it somewhat larger than the 65,000 dalton mango enzyme (Srere et al. 1971). The PHMB-treated enzyme also shows changes in its electrophoretic properties (Greenblatt and Sarkissian unpublished). The evidence presented here demonstrates that citrate synthase of various plants is sensitive to sulfhydryl reagents suggesting that sulfhydryl reactivity is a not unusual property of plant citrate synthase. In addition we show that molecular weight as large as or larger than that reported in microbial systems can occur in a blue-green alga.

Inorganic minerals in coals can be identified advantageously if they are concentrated by removal of the organic matter of the coal. The concentrating method involves the use of 30–35% hydrogen peroxide. Several days of treatment with this reagent at 20–80°C are required, depending on the substance; anthracite, the most difficult material, requires a few weeks. Under the conditions used most minerals are stable with the exception of carbonates and pyrites which slowly become oxidized to sulfate. Calcium oxalate was found to form in the peroxidation of lignite which contains appreciable amounts of calcium; no other coal residue studied contained oxalates. Carbon analyses indicated the extent of removal of the organic material. Infrared and X-ray techniques were used to identify the minerals present. Some portions of a bituminous coal were found to be intimate mixtures of organic and mineral matter and were quite resistant to peroxidation.

The reactivity of diethylmagnesium and ethylmagnesium bromide towards 2-cyclohexenone in various solvents is studied. The 1,2 addition is always predominant, but diethylmagnesium adds almost exclusively in 1,2 manner to this ketone while ethylmagnesium bromide gives both 1,2 and 1,4 addition products with a ratio dependent of the solvent basicity. Thus, in hydrocarbons (hexane, benzene), the magnesium reagents behave similary; and with more basic solvents, for EtMgBr the yield of the 1,4 addition product increases and that of the 1,2 addition product decreases. With another α,β-ethylenic ketone, trans-3-penten-2-one, 1,4 addition occurs predominantly with both magnesium reagents, diethylmagnesium and ethylmagnesium bromide, but diethylmagnesium gives again much more 1,2 addition product than ethylmagnesium bromide.