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The peculiarities of the LPE technique in obtaining multilayer AlGaAs heterostructures are considered. The internal quantum efficiency of radiative recombination close to 100% and record values (up to 45%) for the external quantum efficiency have been achieved due to the reduction of the active defects at heteroboundaries. The peculiarities of selective LPE of AlGaAs heterostructures and LPE on profiled substrates are also considered. The method developed was used for improving the characteristics of LEDs and for the fabrication of LED monolitic arrays.

The thermal decompositions of the even silver dicarboxylates from silver oxalate to silver sebacate were studied. In vacuum, the dicarboxylates decomposed to give metallic silver, CO2 and organic diradicals as primary products, and polymers as secondary products. The higher silver dicarboxylates were much more stable to thermal treatment than silver oxalate, probably due to the initiation of decomposition of all carboxylates except silver oxalate by the rupture of a Ag-O and not a C-C bond.

1. The 7-methoxy-1,2-bis-(hydroxymethyl)-hydrophenanthrenes (VI), (VIII), (IX), and (X) have been synthesized by the lithium aluminium hydride reduction of the dimethyl esters of cis-cis-Δ4- and cis-Δ4a(10a)-7-methoxyhexahydrophenanthrene-1,2-dicarboxylic acids (V) and (VII) and the dimethyl esters of cis-syn-cis- and cis-anti-cis-7-methoxyoctahydrophenanthrene-1,2-dicarboxylic acids (XI) and (XIII). 2. The hydrogenation of the 7-methoxy-1,2-bis-(hydroxymethyl)-hexahydrophenanthrenes (VI) and (VIII) over 30%Pd/SrCO3 takes place spatially non-selectively and leads to a mixture of the two possible geometrical isomers of 7-methoxy-1,2-bis-(hydroxymethyl)-octahydrophenanthrene.

1. A study was made of the oxidation of the anhydride and diester of syn-cis-1,2,3,5,6,7,8,8a-octahydro-1,2-naphthalenedicarboxylic acid (I) and (XXIV) by peroxyacetic acid and it was shown that this reaction proceeds in the two possible steric directions with the formation of equal amounts of the corresponding isomericα- andβ -oxides. 2. The configurations of the isomeric oxides (II), (III) and (XXVI) were demonstrated by a series of chemical conversions and a study was made of some of their stereospecific conversions, which were con firmed by an examination of molecular models. 3. It was shown that theα-oxide (II) is capable of ready trans-diaxial opening of the oxide ring at the C-O bond at C10 with the formation of the 4-hydroxy-γ -lacto acid (IV), while theβ -oxide (III) is more stable and during a similar reaction undergoes opening of the oxide ring at the C4 bond with inversion of the configuration at this carbon atom. 4. An investigation was made of the reactions ofβ -oxides (III) and (XXVI) with hydrogen chloride, leading to the formation of trans-chlorohydrins (XVI) and (XIX), capable of lactonization into the corresponding 4-chloro-γ -lacto acids (XVII) and (XVIII) of the trans-decahydronaphthalene series, whose configurations corresponded to the 4-hydroxy-γ -lacto acid (IV).

1. A study has been made of the lactonization of the cis-1,2,3,5,6,7,8,8a-octahydromethyl-1,2-naphthalene-dicarboxylic acids (I) and (II), and also of the cis diesters (VI) and (VII), and evidence relating to the structures of the resulting cis lactone acids (III) and (XV) has been presented. 2. It has been shown that, of the epimeric trans acids (VIII) and (XX), only the trans acid (VIII) is capable of undergoing lactonization — a result in accord with the spatial configuration of (VIII)_. The trans acid (XX) and the trans acids (IX) and (XIX), which have inter-ring double bonds, are incapable of lactonization. 3. An examination of molecular models has provided an explanation of the experimentally observed steric hindrance to the lactonization of the trans-octahydromethyl-1,2-napthalenedicarboxylic acids (IX), (XIX), and (XX).

1. An apparatus for investigating the kinetics of rapid reactions in solution by the stopped-jet method, permitting the recording of reactions with half-conversion times greater than 1 msec according to the change in the optical density in the ultraviolet or visible region, was described. The jet portion is made as an attachment to an SF-4 spectrophotometer. 2. An example of measurement of the rate of complex formation between molybdate and propyl gallate on this apparatus was cited.

1. Theγ-aldehydic acids prepared from the diene-synthesis adduct formed in the condensation of 4-ethoxy-2-buten-4-olide (the ethylψ-ester of malealdehydic acid) with butadiene exist as mixtures of tautomeric forms (lactol and aldehydic acid) in benzene, methanolic, and aqueous solutions. 2. Like theγ-aldehydic acids themselves, theirψ-esters react with hydrazine hydrate with formation of the corresponding hydrogenated phthalazinones. 3. The hydrogenated phthalazinones so obtained can serve as starting substance for the synthesis of apressine analogs.

1. Oxidation of the anhydride of 1, 2, 3, 5, 6, 7, 8, 8a-octahydro-1,2-naphthalenedicarboxyltc acid (III) with peroxyacetic acid gave the syn-cis 4-hydroxy y-lactone acid (V), formed by intramolecular lactonization of the epoxide (IV), which is formed intermediately. 2. Chromium trioxide oxidation of the syn-cis 4-hydroxy y-lactone acid (V) gave the syn-cis 4-oxo γ-lactone acid (VIII), and this product and its ester (IX) were used in the synthesis of trans -syn-cis-decahydro1, 2-naphthalenedicarboxylic acid (1), The latter was obtained in good yield by the hydrogenolysis of the 4=oxo γ-lactone acid (VIII), brought about by treatment at the boil with zinc in a mixture of hydrochloric acid and methanol. 3. The trans-syn-cis acid (I) that we have now synthesized is the seventh of the eight possible isomers of decahydro-1,2-naphthalenedicarboxyUc acid to be discovered. Its steric transformations were studied with the aid of molecular models. The question of the configuration and stability of the last (eighth) trans-syn-trans isomer (II) was discussed; it is very unlikely to exist under ordinary conditions.

1. We synthesized the pure cis-trans isomers of Δ4-octalin-1-carboxylic acid, its methyl ester, 1-hydroxymethyl-Δ4-octalin, and Δ4-1-octalinaldehyde, and also the methyl ester of cis-Δ4-1-octalylacetic acid and cis-1-(2-hydroxyethyl)-Δ4-octalin. 2. A study was made of the epimerization of Δ4-1-octalinaldehyde.

1. The diene condensation of 4-ethoxy-2-buten-4-olide (the ethylψ-ester of malealdehydic acid) (I) with cyclopentadiene goes sterically selectively with formation of an adduct (II) of endo configuration, the hydrogenation product (IV) of which is incapable of thermal isomerization into the exo form. 2. Comparison of the results of the hydrogenation of the unsaturatedψ ester (II), theγ-aldehydic acid (III), and the normal methyl ester of (III) [ (VI) ] proves the cyclic (lactol) structure of the γ-aldehydic acids (III) and (V). 3. The isomerization of theψ-esters (II) and (IV) under the influence of concentrated sulfuric acid in methanol leads not to the corresponding transγ-aldehydic esters of normal structure, but to their dimethyl acetals (XIII) and (XIV).

1. A study has been made of the diene condensation of 1-vinylcyclohexene (I) with citraconic anhydride (II), and it has been shown that in this reaction the ortho and meta adducts (III) and (IV) are formed in the proportions of 5 : 1 and in an overall yield of 92%. Hydrolysis of the cis anhydrides (III) and (IV) yielded the corresponding cis-1,2,3,5,6,7,8,8a-octahydromethyl-1,2-naphthalenedicarboxylic acids (V) and (VI), and the structures and spartial configurations of these have been proved. 2. The unsaturated cis anhydrides (III) and (IV), and also the corresponding cis acids (V) and (VI), are readily hydrogenated in a sterically selective manner at a platinum catalyst into the corresponding saturated compounds (VII), (VIII), (XV), and (XVI), the direction of the reaction being determined by the screening effect of the cis substituents at (C-1)-(C-8a) on the double bond. 3. By the isomerization of the cis diesters (IX), (X), and (XVII) with the aid of sodium methoxide, the corresponding trans acids (XI), (XII), and (XIX) have been obtained in good yield, and this reaction may provide a convenient method for their synthesis. The hydrogenation of the unsaturated trans acid (XIX), unlike that of the isometric trans acid (XI), is not sterically selective. 4. By treatment with acetyl chloride in a mixture of acetic anhydride and acetic acid, the cis diesters (IX) and (XVII) have been caused to undergo isomerization with displacement of the double bond to give the cis diesters (XIII) and (XXI). Further isomerization of these in presence of sodium methoxide yields the trans acids (XIV) and (XXII), which have an inter-ring double bond. These acids, as also the esters (XIII) and (XXI), cannot be hydrogenated over a platinum catalyst under the usual conditions. 5. Irrespective of the temperature (within the range 100–230°), the condensation of 1-vinylcycohexene with citraconic anhydride proceeds by exo-addition.

1. The synthesis of the four possible geometric isomers of 7-methoxy-l,2,3,4,4a,9,10,10a-octahydrophenanthrene-l, 2-dicarboxylic acid with a cis-connection of cycles has been achieved, and their configurations have been proved. 2. The possibility of conversion transformations of the cis-syn-cis-acid (III) has been established; this possibility explains the formation of two isomeric trans-acids (VI) and (V), and the cis-syn-cis-diester (XII).

1. The condensation of 1-(1-ace toxyvinyl)cyclohexene (I) with maleic anhydride was studied: it results in an 80% yield of the anti-cis anhydride (III), which is quantitatively hydrolyzed by water to anti-cis-4-acetoxy 1,2,3,5,6,7,8,8a-octahydro-1,2-naphthalenedicarboxylic acid (IV), which gives the anti-cis acetoxy diester (V) with diazomethane. 2. By hydrolysis of the acetoxy group in the acid (IV) and the diester (V) we prepared the traps-anti-cis keto acid (VI) and the traps-anti-traps keto diester (X), and Clemmensen reduction of these gave the previously described traps-anti-cis decahydro-1,2-naphthalenedicarboxylic acid (IX) and the traps-anti-traps-decahydro 1,2-naphthalenedicarboxylic diester (XI), thus confirming the configurations of these last compounds. 3. The steric transformations of some monoesters of this series were studied, and it was shown that they readily undergo isomerization at the 2-alkoxycarbonyl group.

1. A. detailed investigation has been made of the conditions for the condensation of 2-methyl-2-cyclohexen-1-one (II) with 2-methoxy-1,3-butadiene (I). 2. It has been shown that this condensation proceeds in two directions with formation of 2,3,4a,5,8,8a-bexahydro-6-methoxy-8a-methyl-1(2H)-naphthalenone (III), and 2,3,4a,5,8,8a-hexahydro-7-methoxy-8a-methyl-1(2H)-naphthalenone (IIIa) in a ratio of approximately 5:1. The yield of condensation products has been increased from 25 to 45–50%. 3. A detailed study has been made of the condensation of the compounds III and IIIa with alkali-metal acetylides in liquid ammonia. By this means yields of 50–55% of the acetylenic hydroxy ketones (V) and (Va) have been obtained, and these have been hydrogenated selectively in the presence of a Pd catalyst, yielding the vilyl hydroxy ketones (VI) and (VIa), which have been dehydrated with potassium hydrogen sulfate to give the d?enomes (VII) and (VIIa). The structures of these dienones and related compounds have been rigorously proved by converting them into known methylchrysenes (XX and XXa), and also by converting the dienone (VII) into the known 2-methylphenanthrene.

The extent of phenotypic reversal by 5-fluorouracil of an amber mutation of the phage T4D increases at high pH. The magnitude of the increase depends strongly on the composition of nutritive medium.

1. A study was made of the dependence of the lactonization reaction on steric structure for all four isomeric 1,2,3,5,6,7,8,8a-octahydro-1,2-naphthalenedicarboxylic acids (I), (X), (XIII), and (XIX). 2. It was shown that the syn-cis dicarboxylic acid (I) and the syn-traps dicarboxylic acid (X) are lactonized to the corresponding isomeric γ-lactone acids (II) and (XI), which contain γ-lactone rings. The acid (X) is lactonized considerably less readily than the isomeric acid (II). 3. Lactonization of the anti-cis dicarboxylic acid (XIII) proceeds with difficulty and gives a mixture of the chloro dicarboxylic acid (XV) and the anti-cis S-lactone (XIV), the structure of which, as a σ-lactone acid, was confirmed by various chemical reactions and by the infrared spectrum. The anti-traps dicarboxylic acid (XIX) was found to be quite incapable of lactonization. 4. It was shown that, as a result of double-bond displacement, the isomeric syn-cis and anti-cis dicarboxylic acids (I) and (XIII) give the same cis-dicarboxylic acid (VIII), which has an intercycle double bond, this being further confirmation of our previous results on the configurations of the acids (I) and (XIII) as epimers with respect to hydrogen at C-8a. 5. The stereochemical peculiarities of the lactonization of the isomeric, 1,2,3,5,6,7,8,8a-octahydro-1,2-naphthalenedicarboxylic acids as a function of their spatial configurations were examined and explained with the aid of molecular models.

1. When 1-vinylcyclohexene was condensed with dimethyl mesaconate, three is trans-1,2,3,5,6,7,8,8a-octahydromethyl-1,2-naphthalenedicarboxylic acids (I), (II), and (III)_were isolated in the proportions of 7 : 7 : 1. The structures and spatial configurations of these acids have been proved. 2. The trans acids (I) and (II), which were obtained in equal amount, are of ortho structure and differ from one another only in the position of the hydrogen atom at C-8a. The trans acid (III), which was obtained in small amount, is a meta isomer in which the hydrogen at C-8a is trans with respect to the carboxyl at C-1. 3. It has been shown that the hydrogenation of the trans acid (I) and of its anhydride (VIII) in presence of platinum oxide proceeds in a selective manner with formation of the individual compounds (IX) and (X), whereas the trans acids (II) and (III) are not hydrogenated selectively under these conditions, but gibe mixtures of stereoisomers. 4. Such sterically selective hydrogenation of 1,2,3,5,6,7,8,8a-octahydromethyl-1,2-naphthalenedicarboxylic acids and their derivatives occurs only when the 8a-hydrogen and the 1-carboxyl are arranged cis to one anothers this view is supported by an examination of atomic models. 5. The trans diesters (XI) and (XVI) are unable to undergo isomerization with displacement of the double bond to the inter-ring position, such as occurs in the case of the corresponding esters of the cis series.

1. Six of the eight theoretically possible isomers of decahydro-1,2-naphthalenedicarboxylic acid (I), (II), (VI), (X), (XIV), and (XX) are described, and in each case a rigorous determination of spatial configuration is made. 2. A study is made of the chemical transformations of all the synthesized isomeric decahydro-1,2-naphtha - lenedicarboxylic acids and of the cis-trans isomerization of the corresponding mono- and di-esters in presence of sodium methoxide. It is shown th t the isomers obtained are relatively stable both to heat and to alkaline reagents. 3. On the basis of the theory of equatorial-polar bonds in the cyclohexane molecule and of an examination of molecular models, all the peculair features of the mutual transofrmations of the six isomeric decahydroacids and their esters can be explained.

1. The alkenyl carbonium ions that are formed on the surface of H-mordenite when alkylbenzenes are alkylated with propylene are secondary products, and do not take part in the alkylation reaction. 2. The alkylation reaction and the hydrogen redistribution can proceed with the involvement of the same alkyl carbonium ions.

1. 1-Vinyl-4-tert-butyl-1-cyclohexene (I) was synthesized for the first time, and it enters into the diene condensation with more difficulty than does 1-vinyl-1-cyclohexene. 2. The yield of the adduct of 1-vinyl-4-tert-butyl-1-cyclohexene with methyl acrylate is increased substantially by running the reaction in the presence of aluminum chloride.