ISSN:0021-2148    

DOI:10.1002/ijch.197100015

出版商:WILEY‐VCH Verlag    

年代:1971

数据来源: WILEY

ISSN:0021-2148    

DOI:10.1002/ijch.197100016

出版商:WILEY‐VCH Verlag    

年代:1971

数据来源: WILEY

摘要:

AbstractThe preparation of fully protected derivatives of DL‐α‐hydroxyalanine is described. Several possible routes leading to protected DL‐α‐hydroxyalanine and α‐hydroxyglycine were explored. Attempts to remove the protecting groups led in most cases to the disruption of the molecule. The N‐carboxyanhydride of O‐benzyl‐DL‐α‐hydroxyalanine was prepared and trimerised to give dehydroalanyl‐O‐benzyl‐DL‐α‐hydroxyalanyldehydroalanine. This is a novel type of polymerization of N‐carboxyanhydrides concurrent with elimination of benzyl alcohol. A generally useful method of purification of oily half esters of dicarboxylic acids through their crystalline di

ISSN:0021-2148    

DOI:10.1002/ijch.197100017

出版商:WILEY‐VCH Verlag    

年代:1971

数据来源: WILEY

摘要:

AbstractThe N‐carboxy‐anhydrides of β ‐ benzyl O‐t‐butyl‐threo‐β‐hydroxy‐DL‐ and L‐aspartate were polymerized. The two protecting groups, i. e., t‐butyl and benzyl groups, could be removed stepwise without degr

ISSN:0021-2148    

DOI:10.1002/ijch.197100018

出版商:WILEY‐VCH Verlag    

年代:1971

数据来源: WILEY

摘要:

AbstractSeveral halogen derivatives of isoquinoline were prepared and their electric dipole moments determined. The dipole moment of isoquinoline forms an angle of approximately 110° with the bond common to both rings of the molecule

ISSN:0021-2148    

DOI:10.1002/ijch.197100019

出版商:WILEY‐VCH Verlag    

年代:1971

数据来源: WILEY

摘要:

AbstractThe experimental results of the photochemical transformation of purine, adenine, hypoxanthine and caffeine were tested by using two different sets of parameters in the HMO formalism. Net charges and bond orders are in accord with the photochemical reactivities of caffeine and purine, while for the other cpds. examined the agreement is less satisfactory. The perturbation index ASP (atom ‐self‐polarisability) gives a good estimate of the reaction site, while predictions with Fukui's frontier orbital theory are less adequ

ISSN:0021-2148    

DOI:10.1002/ijch.197100020

出版商:WILEY‐VCH Verlag    

年代:1971

数据来源: WILEY

摘要:

AbstractThe temperature dependence of the polymerization rate is investigated using the NCA's of β‐benzyl L‐aspartate and γ ‐benzyl L‐glutamate. Activation energies for polymerizing the above NCA's are 13 and 9 Kcal per mole, respectively. Entropies of activation and Arrhenius constants, A, are also calculated and discussed in terms of the polymerization mechanism. The significance of the proton‐transfer reaction in the “active monomer” mechanism is recognized through a kinetic isotope effect and also by comparing the polymerization rates of L‐alanine NCA and its structural analog L‐alanine N‐thiocarboxyanydride. It is theorized that a changing position of equilibrium of the neutralization step decreases the concentration of “active monomer”, thereby slowin

ISSN:0021-2148    

DOI:10.1002/ijch.197100021

出版商:WILEY‐VCH Verlag    

年代:1971

数据来源: WILEY

摘要:

AbstractHückel‐type calculations are used to rationalize the known properties of fused benzothiophenes and to predict behavioral trends which have not been investigated as y

ISSN:0021-2148    

DOI:10.1002/ijch.197100022

出版商:WILEY‐VCH Verlag    

年代:1971

数据来源: WILEY

摘要:

AbstractThe adsorption of iodine and bromine by polyethylene sulfide‐containing fabrics was investigated. It was found that the halogens could be adsorbed from aqueous solution as well as from a saturated halogen atmosphere. Adsorption was attributed to complexation by the sulfide bonds in the polymer. Adsorption from aqueous solution led to the formation of a complex with a molar ratio of halogen molecules (X2) to ethylene sulfide units of 1:1, while that from gaseous iodine a ratio of 2 was obtained. Complexation was accompanied by a little degradation of the polysulfide which was attributed to halogenation of the polyethylene sulfide. High adsorption of bromine led to complete degradation of the cotton fabric due to oxidation of the cellulose. The adsorption of polyethylene sulfide in the fabric was much higher than that of homopolyethylene sulfide itself under comparable condition

ISSN:0021-2148    

DOI:10.1002/ijch.197100023

出版商:WILEY‐VCH Verlag    

年代:1971

数据来源: WILEY

摘要:

AbstractGraft polymers of Nylon‐6, 6 on cellulose acetate were obtained by successive alternate controlled addition of adipoyl chloride followed by 1,6‐hexane diamine to the potassium alkoxide derivative of cellulose diacetate in tetrahydrofuran. The graft polymers were fractionated and isolated from homopolymer fractions. Their Nylon‐6, 6 content increased upon increasing the monomer concentr

ISSN:0021-2148    

DOI:10.1002/ijch.197100024

出版商:WILEY‐VCH Verlag    

年代:1971

数据来源: WILEY