Synthesis and mesomorphism of mixed ether-ester tail triphenylene discotic liquid crystals with long alkyloxy peripheral chains

Symmetrical and asymmetrical triphenylene discotic liquid crystals with two kinds of different peripheral chains, sym-TP(OC₁₁H₂₃)₃(O₂CR)₃ and asym-TP(OC₁₁H₂₃)₃(O₂CR)₃, (R=CH₂OC₂H₅, CH₂OC₃H₇, CH₂OC₄H₉, CH₂OC₅H₁₁, C₃H₇, C₄H₉, C₅H₁₁, C₆H₁₃, C₇H₁₅) were synthesized. Their thermotropic liquid crystalline properties were studied by polarizing optical microscopy (POM) and differential scanning calorimetry (DSC). The results showed that the asymmetrical compounds had higher melting and clearing points than that of their corresponding symmetrical compounds. For the same series of compounds, TP(OC₁₁H₂₃)₃(O₂CR)₃, their melting points decrease and clearing points increase gradually with the lengthening of ester chains. Most of the β-oxygen containing esters of triphenylene derivatives, TP (OC₁₁H₂₃)₃(O₂CR)₃, (R=CH₂OC₂H₅, CH₂OC₃H₇, CH₂OC₄H₉, CH₂OC₅H₁₁), symmetrically or asymmetrically attached on triphenylene cores, have higher melting and clearing points than those of triphenylene derivatives, TP(OC₁₁H₂₃)₃(O₂CR)₃, (R=C₄H₉, C₅H₁₁, C₆H₁₃, C₇H₁₅), with the same length of peripheral chains. The triphenylene derivatives with longer peripheral chains have shown mesophase at room temperature. __________ Translated from Chemical Research and Application, 2007, 19(10) (in Chinese)     

Molecular aggregation in selected crystalline 1:1 complexes of hydrophobic d‐ and l‐amino acids. IV. The l‐phenylalanine series

The amino acid l ‐phenylalanine has been cocrystallized with d ‐2‐aminobutyric acid, C₉H₁₁NO₂·C₄H₉NO₂, d ‐norvaline, C₉H₁₁NO₂·C₅H₁₁NO₂, and d ‐methionine, C₉H₁₁NO₂·C₅H₁₁NO₂S, with linear side chains, as well as with d ‐leucine, C₉H₁₁NO₂·C₆H₁₃NO₂, d ‐isoleucine, C₉H₁₁NO₂·C₆H₁₃NO₂, and d ‐allo‐isoleucine, C₉H₁₁NO₂·C₆H₁₃NO₂, with branched side chains. The structures of these 1:1 complexes fall into two classes based on the observed hydrogen‐bonding pattern. From a comparison with other l :d complexes involving hydrophobic amino acids and regular racemates, it is shown that the structure‐directing properties of phenylalanine closely parallel those of valine and isoleucine but not those of leucine, which shares side‐chain branching at C^γ with phenylalanine and is normally considered to be the most closely related non‐aromatic amino acid.     

Synthesis and properties of dicyclopentadienyltantalum hydride olefin compounds

Reactions of Cp₂TaCl₂ with RMgCl (R = n-C₃H₇, i-C₃H₇, n-C₄H₉, s-C₄H₉, n-C₅H₁₁ and C₅H₉) give tantalum hydride π-olefin complexes Cp₂Ta(H)L (L = C₃H₆, C₄H₈, C₅H₁₀ and C₅H₈). Two isomers of Cp₂Ta(H)C₃H₆ were obtained. The complexes are useful starting materials for the synthesis of other tantalum hydride species, e.g. Cp₂Ta(H)PEt₃ and Cp₂TaH₃.     

Relations between the electrosorption and the inhibition behaviour of homologous dialkyl-phenyl-phosphine oxides

The electrode transfer reaction of Cd²⁺ has been studied under the influence of the homologous dialkyl-phenyl-phosphine oxides (R)₂·C₆H₅·PO (R=CH₃, C₂H₅, C₃H₇, C₄H₉, C₅H₁₁) using d.c. polarography. The rate constants were correlated with the adsorption data. The comparison of the rate constants with the surface pressure values shows that the rate constants decrease linearly with increasing surface pressure values. It could also be shown that the inhibitory effect grows as the length of the alkyl groups increases.     

Synthesis and properties of dicyclopentadienyltantalum(III) carbonyl compounds

Reaction of Cp₂Ta(H)L (L = C₃H₆, C₄H₈, C₅H₁₀ and C₅H₈) with CO under mild conditions gives alkyltantalum carbonyl complexes Cp₂Ta(CO)R (R = C₃H₇, C₄H₉, C₅H₁₁ and C₅H₉, respectively). Depending upon the position of the olefin relative to the hydride ligand in the hydride-olefin complex, Cp₂Ta(CO)H is also formed during the carbonylation reaction. Reduction of Cp₂TaCl₂ by potassium or t-BuMgCl under one atmosphere of CO affords the very stable compound Cp₂Ta(CO)Cl in moderate yields. Reaction of Cp₂Ta(CO)Cl with RLi or RMgX does not give the Cp₂Ta(CO)R complex.     

Studies on the Preparation and Properties of Thiol Derivatives of Biscyclopentadienyl Molybdenum (VI) and Bisindenyl Molybdenum (VI) Oxide Dichloride

Biscyclopentadienyl molybdenum (VI) oxide dichloride (I) and bisindenyl molybdenum (VI) oxide dichloride (II) react with various thiols in tetrahydrofuran and from the complexes of the type (C₃H₅)₂MoO (R₂) and (C₉H₇)₂MoO (R₂) wherein R may be S CH₈, S C₂H₅, S C₃H^N₇, S C₃H₇, S C₄Hⁿ₉, or S C₄H₃ or S C₃H₁₁. The preparation, thermal stabilities, physical characteristics and infrared spectra of these complexes have been studied in this paper.     

Carbon-13 chemical shift assignment of some organophosphorus compounds: 1—Dialkyl and diaryl (alkylamido)phosphates with general formula Y2P(X)NHR

Carbon-13 chemical shifts and the POC, POCC, PNC and PNCC coupling constants of 18 compounds containing the amine moiety, and with the general formula Y₂P(X)NHR [Y=C₂H₅O, C₆H₅O, CH₂O, Y₂=1,2-dioxybenzene; X = O or S; R = H, CH₃, C₂H₅, PhCH₂CH₂, (CH₃)₂CH, C(CH₃)₃, C₆H₁₁, C₆H₅, C₆H₅NH] have been determined. The Y₂P(X) group shows a sterically induced effect on the amine moiety; the ¹³C chemical shift of the Y group is, however, almost unaffected on replacing P(O) by a P(S) group.     

Nitrosyl derivatives of group VI metals containing monodentate amines

Summary Passage of a slow stream of nitric oxide through a benzene solution of M(CO)₅(Am), (M = Mo and W; Am = BuNH₂, C₆H₁₁NH₂, PhCH₂NH₂, C₅H₁₁N, C₅H₅N and BuNO) yielded dimeric [M(NO)₃(Am)]₂ complexes which have been characterized by elemental analysis, magnetic data and i.r. spectra. The i.r. data indicate the presence of terminal as well as of bridging nitric oxide in the complexes.     

The electrophilic addition of thiols to olefins: A theoretical and experimental study

Density functional theory with the B3LYP hybrid functional and 6–31G* basis set was used to study the geometric and electronic structure of H₂C = CHR (R = H, CH₃, C₂H₅, C₃H₇, C₄H₉, and C₅H₁₁) olefins, their carbocations formed in the addition of the proton to the olefins, R′-S-H aliphatic thiols (R′ = H, CH₃, C₂H₅, and C₃H₇), the products of the addition of thiols to carbocations, and the final products of the addition of thiols to olefins. The proton affinity of the olefins and the products of the addition of thiols to olefins was calculated. The conclusion was drawn that the limiting stage in the nonradical addition of thiols to olefins catalyzed by acids was proton transfer from the protonated reaction product to the olefin. The theoretical results were compared with the experimental data on the electrophilic addition of polymercaptan to heptene-1.     

Alcoholysis of (2-methoxycarbonyl)ethyltin compounds

Under acid or base catalysis, di(2-alkoxycarbonylethyl)tin dichlorides of various R groups, (ROCOCH₂CH₂)₂SnCl₂, can be prepared conveniently in high yield by alcoholysis of (CH₃OCOCH₂CH₂)₂SnCl₂ in various alcohols, ROH (R = C₂H₅, C₄H₉, iso-C₄H₉, C₅H₁₁, C₆H₅CH₂, C₄H₉CH(C₂H₅)CH₂). When excess acid or base is present in the aqueous solution, (ROCOCH₂CH₂)₂SnCl₂ eliminate ROH and precipitate as C₆H₈O₄Sn regardless of the R group. C₆H₈O₄Sn can be converted into various (ROCOCH₂CH₂)₂SnCl₂ derivatives on dissolving in alcoholic HCl solutions.     

Quenching of electronically-excited UF6 emission by selected organics

Rate constants at 25°C have been evaluated for the quenching of electronically excited UF6 by selected organic molecules. Values for the rate constants at 25°C (units of 10¹¹ ρ/mole s) for CH₄, C₂H₆, C₂F₆, CHF₂CHF₂, C₂H₂, and C₂H₄ are 0.061, 3.8, 0.022, 0.072, 6.0, and 5, respectively.     

Oxidation of γ-stannyl sulfides by monochloramine CB and hydrogen peroxide

The first γ-trimethylstannyl sulfimide, Me³Sn(CH₂)₃S(=NSO₂Ar)C₅H₁₁-n, was synthesized by oxidative imination of Me₃Sn(CH₂)₃SC₅H₁₁-n with ArSO₂(Na)Cl (Ar=C₆H₄Cl-4). Oxidation of γ-trimethylstannyl sulfimide by an alkaline solution of H₂O₂ gave γ-trimethylstannyl sulfoximide, Me₃Sn(CH₂)₃S(O)(=NSO₂Ar)C₅H₁₁-n, and γ-trimethylstannyl sulfone, Me₃Sn(CH₂)₃SO₂C₅H₁₁-n, the latter compound resulting from hydrolysis of the arylsulfimide group. Oxidation of stannyl sulfide by hydrogen peroxide yielded γ-trimethylstannyl sulfoxide, Me₃Sn(CH₂)₃S(O)C₅H₁₁-n (under mild conditions) or γ-trimethylstannyl sulfone (under more severe conditions). Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 2, pp. 371–374, February, 1997.     

有玻璃态和液晶态的胆甾烯基苯并菲的合成及介晶性

将盘状液晶基元苯并菲与手性向列型液晶基元胆甾烯基结合的化合物, 可望出现全新的性质. 合成了含有胆甾烯基的苯并菲化合物C₁₈H₆(OC₅H₁₁)₅(OC₅H₁₀COOCh) (2), 2,7-C₁₈H₆(OC₅H₁₁)₄(OC₅H₁₀COOCh)₂ (4), C₁₈H₆(OR)₃(OC_nH_{2nCOO- Ch)3 (R＝C5H11, C7H15, C9H19, C11H23, n＝1, 5, 10) (6a～6f), C18H6(OC5H10COOCh)6 (Ch: cholesteryl) (8). 偏光显微镜和差示扫描量热法对这些化合物的热致介晶性研究结果显示, 化合物 4, 6a～6e具有手性盘状向列相和玻璃态, 8呈现近晶B相(SB)和玻璃态. 随间隔基长度n和烷基链R碳原子数的增加, 化合物玻璃化温度和清亮点呈下降趋势. 随着胆甾烯基数目减少, 化合物的玻璃化温度和清亮点降低.}     

Synthesis and mesomorphic properties oftrans-[1,4-bis(5-R-pyrimidin-2-yl]-cyclohexanes and 1,2-bis-(5-R-pyrimidin-2-yl)ethanes

New trans-bis(5-R-pyrimidin-2-yl)-1,4-cyclohexanes and-1,2-ethanes (R=C₇H₁₅, C₆H₄OR¹, where R¹=H, COCH₃, C₄H₉, C₅H₁₁, C₈H₁₇) have been synthesized. Only nematic mesophases are found from a study of their mesomorphic properties, except for bis[5-(4-octyloxyphenyl)- and-(4-acetoxyphenyl)pyrimidin-2-yl)-cyclohexanes, which also exhibit smectic properties.Novosibirsk Institute of Organic Chemistry of the Siberian Division of the Russian Academy of Sciences, Novosibirsk 630090, Russia; e-mail: benzol@nioch.nsc.ru. Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 3, pp. 355–360, March, 1999.     

Thermokinetic studies of organotin(IV) carboxylates derived from para-methoxyphenylethanoic acid

Thremogravimetric (TG) studies of a new series of organotin(IV) carboxylates of the general formula R_nSnL_4-n (where R = CH₃, C₂H₅, C₄H₉, C₆H₅, C₆H₁₁ and C₈H₁₇, n = 2, 3 and L = para-methoxyphenylethanoate anion) have been carried out. Horowitz and Metzger method has been used to calculate thermokinetic parameters. It has been found that diorganotin dicarboxylates have larger activation energy than those of corresponding triorganotin carboxylates. Furthermore, the activation energy, Gibb’s free energy, entropy and enthalpy of diorganotin compounds shows the following trend, (CH₃)₂SnL₂ < (C₂H₅)₂SnL₂ < (C₄H₉)₂SnL₂ < (C₈H₁₇)₂SnL₂. This is attributed to steady increase in chain length of the alkyl groups. However, triorganotin compounds do not show such behavior.     

Synthesis of heterylamines

N-Substituted (CH₃, CH₂C₆H₅, C₆H₅) 2-aminoimidazoles, 2-aminobenzothiazoles, and 2-aminopyridine were obtained by cleavage of heterylphenyltriazenes formed from organolithium and organosodium compounds of heterocycles and phenyl azide.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 11, pp. 1552–1554, November, 1972.     

Acidity of organic sulfides

The rate of base-catalyzed hydrogen exchange (bases KNH₂ in NH₃. t-C₄H₃OK in t-C₄H₃OH) has been used to mesure the acidity of sulfides RSCD₃, in which R is CH₃, C₆H₆, C₆H₁₁, or C₅H₈, The cycloalkyli are found to act as electron acceptors. The effects of one and two CH₈ and SC₆H₆ are examined. The sulfides are compered with hydrocarbons and also with 3CH₃, OCH₁ and NCH₃ attached to benzene. The vacant 3d levels of the sulfur stabilize the sulfide carbanions; deuterium exchange shows that the charge distribution ir.p-dimethylaminothiazole is due to pd conjugations. Synthesis routes are described for compounds tagged with deuterium in specified positions: C₆H₁₁SCD₃, C₆H₈SCD₁, C₆H₅SCD₁CH₃, C₆H₃SCD(CH₃)₂, p-(CH₃)₂NC₅H₄SCD₃, and p-(CD₃)₂NC₅H₄SCH₃.     

Carbon skeletal rearrangements in 2-phenylthiophene and 2,5-diphenylthiophene under conditions of electron-impact

The mass spectra of ¹³C-labelled 2-phenylthiophenes and 2,5-diphenylthiophenes were studied. The label distributions for the [HCS]⁺, [C₂H₂S]^+·, [C₈H₆]^+·, [C₉H₇]⁺ and [C₇H₅]S⁺ ions from 2-phenylthiophene and the [HCS]⁺, [C₉H₇]⁺, [C₇H₅S]^+·, and [C₁₅H₁₁]⁺ ions from 2,5-diphenylthiophene were interpreted in terms of both carbon skeletal rearrangements in the thiophene ring and migration of the phenyl substituent. The degree of carbon scrambling in the thiophene ring appeared to be almost independent of the electron beam energy. The formation of some of the fragment ions studied seems to be so fast that no carbon scrambling could be detected at all; in neither case was complete scrambling of the carbon atoms of the thiophene ring observed.     

Dialkylamino-bis(trimethylsilyl)amino-chlorborane und ihre Reaktion mit Natrium-bis(trimethylsilyl)amid

Zusammenfassung Verbindungen des Typs R₂NBCIN(Sime ₃)₂ ^* (R=C₂H₅,ⁱC₃H₇, C₆H₁₁, C₆H₅) bleiben bis zu hohen Temperaturen beständig. Sie reagieren jedoch mit NaN(Sime ₃)₂ unter Übertragung einer Methylgruppe von einem Silicium-zu einem Boratom zu N,N-Bis(trimethylsilyl)-tetramethylcyclodisildiazan und R₂NBmeN(Sime ₃) (R=C₂H₅,ⁱC₃H₇).

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Compounds of the type R₂NBClN(Sime ₃)₂ ^* were prepared. (R=C₂H₅,ⁱC₃H₇, C₆H₁₁, C₆H₅. They do not show any tendency to condense thermally under elimination of trimethylchlorosilane. When these silylaminoboranes were allowed to react with NaN(Sime ₃)₂, complicated rearrangements were observed. The compounds in which R=C₂H₅ orⁱC₃H₇ rearranged under formation of N,N-bis(trimethylsilyl)-tetramethylcyclodisildiazane and R₂NBmeN(Sime)₂. In this reaction a migration of a methyl group from silicon to boron occurs.

     

Mass spectrometry of homoadamantane derivatives

Homoadamantane derivatives can be divided into two groups according to their mass spectra. To the first group belong compounds with electron attracting substituents (COOH, CI, COOCH₃, Br); compounds with electron releasing substituents (OCH₃, OH, NH₃, NHCOCH₃) constitute the second group. The most characteristic feature of the first group compounds is the splitting off of the substituent. The hydrocarbon fragment [C₁₁H₁₇]⁺ thus formed then loses olefin molecules with the formation of corresponding ionic species C_11?nH_17?2n. The 3-substituted compounds of this group undergo thermal Wagner-Meerwein type rearrangements into adamantane derivatives, resulting in the [C₁₀H₁₅]⁺ (m/e 135) ion formation; this is the main difference between 1- and 3-substituted homoadamantanes. The series of [C_nH_2n?6X]⁺ ions (where X = OCH₃, OH, NH₂, NHCOCH₃, n = 6 to 10) are characteristic of the mass spectra of the second group compounds, the ion [C₆H₆X]⁺, [M ? C₅H₁₁]⁺ being the most abundant. The intensity ratio of [M ? C₅H₁₁]⁺ to [M ? C₄H₉]⁺ ions is 10:1 for 1-substituted and 3:1 for 3-substituted compounds of this group, allowing the location of the substituent. Some individual features of the spectra are also reported.