摘要:

AbstractThe anodic behavior of the manganese electrode in borate buffer solutions have been studied by potentiostatic and galvanostatic electrochemical techniques. Three distinct steps determined on the charging curves are attributed to the formation of Mn (OH)2, MnOOH and MnO2. The manganese dioxide formed anodically in pH 11 borate solution may be reduced cathodically with high faradaic efficiency.

ISSN:0018-019X    

DOI:10.1002/hlca.19730560402

出版商:WILEY‐VCH Verlag GmbH    

年代:1973

数据来源: WILEY

摘要:

AbstractThe reaction of tris‐crotyl‐boron with vinylic olefins in the presence of triethyl‐aluminium, results in the addition of an α‐methylallyl group and an aluminium atom to the double bond, as indicated by the hydrolysis products. The stereochemical aspect of the reaction is discussed and a mechanism is proposed to explain the preferential formation of one diaster

ISSN:0018-019X    

DOI:10.1002/hlca.19730560403

出版商:WILEY‐VCH Verlag GmbH    

年代:1973

数据来源: WILEY

摘要:

AbstractThe substoichiometric extraction of Hg2+using diethyldithiocarbamic acid and203Hg tracer was studied. Chloroform was employed to remove the complexes from the aqueous media which were 0.5MH2SO4or 1MHClO4and 0 to 5MNaCL. ‐ Systems containing Cl−allowed extraction of Hg2+for all DDC/Hg molar ratios, the extracted complexes being HgCl(DDC) and Hg(DDC)2. Their exchange constant was determined. ‐ In the absence of Cl−, no extraction could be effected in either system if the DDC/Hg molar ratio was1, the extraction of Hg2+increased linearly with the addition of DDC, the extracted complex being H

ISSN:0018-019X    

DOI:10.1002/hlca.19730560404

出版商:WILEY‐VCH Verlag GmbH    

年代:1973

数据来源: WILEY

摘要:

AbstractA new procedure for the synthesis of peptides on a soluble carrier is described. It relies on gel filtration for the removal of low molecular weight reactants from the peptide‐polymer complex after each cycle. The advantages of the method are assessed and the insight into the problematics of the carrier synthesis which it provides are discussed. Finally, the use of a monovalent, soluble carrieer molecule of defined chemistry is proposed. Such a carrier should reduce the problems of carrier synthesis to the purely chemical ones commonly associated with peptide synthesi

ISSN:0018-019X    

DOI:10.1002/hlca.19730560405

出版商:WILEY‐VCH Verlag GmbH    

年代:1973

数据来源: WILEY

摘要:

AbstractThe synthesis of rac. N‐t‐butyloxycarbonylthiobenzylglycyl‐thiobenzylglycine is described. Cyclisation experiments to the corresponding 3,6‐epi‐dithio‐piperazindion(2,5) were u

ISSN:0018-019X    

DOI:10.1002/hlca.19730560406

出版商:WILEY‐VCH Verlag GmbH    

年代:1973

数据来源: WILEY

摘要:

AbstractIsopterin (1), its 6,7‐diphenyl (2) and 4‐dimethylamino derivative (3) react after silylation by hexamethyldisilazane with halogenoses7and8to the blocked isopterin‐N‐1‐nucleosides9,10,11,20and22, which form the free ribosides12,13and14and 2‐desoxyribosides21and23on saponification. The easy nucleophilic substitution of the 4‐amino substituents allows the synthesis of further derivatives (15) as well as formation of lumazine nucleosides (17and18) by alkaline hydrolysis. The structures of the new compounds have been elucidated by UV. and NMR. spectroscopic i

ISSN:0018-019X    

DOI:10.1002/hlca.19730560407

出版商:WILEY‐VCH Verlag GmbH    

年代:1973

数据来源: WILEY

摘要:

AbstractThe formation ofD‐penicillamine‐L‐cysteine mixed disulfide from benzylpenicilloic acid, benzylpenilloic acid and benzylpenicilloyl amide derivatives inL‐cysteine suspensions at pH 7,6 and 37° was studied. The reaction is faster than direct penicilloylation of proteins known to be a route to penicilloyl antigenic determinants. The production of S‐bound penicillamine on protein from penicilloyl compounds must therefore definitely be considered as a potential antigenforming step. The reaction may be partly if not fully blocked by acylation of the thiazolidine nitrogen of penicilloyl compounds. When formylation is applied a considerable reduction of the capacity of penicilloyl antigenic determinants to interact with anti‐penicilloyl antibody is noted. AD‐penicillamine‐specific test antigen was prepared by bindingD‐penicillamineviathioether links to a partly succinylated poly‐L‐lysine. Clinical test reactions elicited with this conjugate and with penicilloic acid cannot be well correlated. Penicilloic acid probably detects reactions of undefined specificity in addition toD‐pen

ISSN:0018-019X    

DOI:10.1002/hlca.19730560408

出版商:WILEY‐VCH Verlag GmbH    

年代:1973

数据来源: WILEY

摘要:

AbstractThe dehydrogenation of 1,4‐cyclohexadiene (1)cis‐3,6‐dimethyl‐1,4‐cyclohexadiene (2) andtrans‐3,6‐dimethyl‐1,4‐cyclohexadiene (3) with triphenylmethylfluoroborate in acetonitrile or 2,3‐dichloro‐5,6‐dicyanobenzoquinone (DDQ) proceeds in the same reactivity sequences2>1>3. The mechanism of the dehydrogenation of 1,4‐cyclohexadienes with triphenylmethylfluoroborate and DDQ is discussed in the light of these results and in view of th

ISSN:0018-019X    

DOI:10.1002/hlca.19730560409

出版商:WILEY‐VCH Verlag GmbH    

年代:1973

数据来源: WILEY

摘要:

AbstractThe reaction of elemental white phosphorus with N‐alkyl acrylamides and N,N‐dialkyl acrylamides in the presence of a base is described and the physical properties of 8 new tertiary phosphine oxides of general formula (R2NCOCH2CH2)3PO (R = H, CH3, C2H5,(CH2)4, (CH2)5, and C2H4OC2H4, CH2CHCH2) are reported. Interaction of white phosphorus with RNCS, RNCO, azo‐bis‐isobutyronitrile, Ph2NNPh2, vinyl acetate, vinyl ethyl ether, and expoxides h

ISSN:0018-019X    

DOI:10.1002/hlca.19730560410

出版商:WILEY‐VCH Verlag GmbH    

年代:1973

数据来源: WILEY

摘要:

AbstractNitrilo‐tri(methylenephosphonic acid) and hydroxyethylidenediphosphonic acid are esterified in high yield when treated with excess orthoformic acid ester under reflux. Because of the high temperature necessary to effect esterification a partial isomerization of hydroxyethylidenediphosphonate to the phosphate‐phosphonate isomer V takes place. Chlorination of N(CH2PO3H2)3or a mixture of the ester and the acid with PCl5yields tris(chloromethyl)amine, N(CH2Cl)3. Interaction of N(CH2Cl)3and (EtO)3P yields nitrilo‐tri(methylenephosphonate), which on hydrolysis with HCl conc. produces N(CH2PO3H2)3. Chlorination of a mixture of hydroxyethylidene‐diphosphonic acid and the corresponding ethyl ester IV which contained the phosphate‐phosphonate isomer V gave the products VII to XI. Chlorination of the acid III with PCl5gave 4 products,i.e., VIII, IX, XI and Cl2(O)POP(O)Cl2. The1H‐ and31P‐NMR. spectra of the products

ISSN:0018-019X    

DOI:10.1002/hlca.19730560411

出版商:WILEY‐VCH Verlag GmbH    

年代:1973

数据来源: WILEY