Pyryliumverbindungen. 38. Zur Ringtransformation von 2,4,6-Triaryl-thiopyryliumsalzen mit Essigsäureanhydrid zu Arylbenzenen und Thiobenzophenonen

Pyrylium Compounds. 38. About the Ring Transformation of 2,4,6-Triarylthiopyrylium Salts by Acetic Acid Anhydride to Arylbenzenes and Thiobenzophenones 2,4,6-Triarylthiopyrylium salts 5 react in the presence of an appropriate condensing agent (sodium acetate, carbonate, methoxide, tert-butoxide or potassium acetate) with acetic acid anhydride to yield arylbenzenes 3 and thiobenzophenones 6 . This ring transformation represents the first example of the conversion of the moiety into the thiocarbonyl group Under the same conditions 3,5-dimethyl-2,4,6-triphenylthiopyrylium perchlorate ( 13 ) forms via [1,5]-sigmatropic rearrangement the thiobenzophenone 15 . The structure of the new compounds 6 was proved by spectroscopic methods as well as by degradation reactions. Thus, hydrogen peroxide converts 6a to the known benzophenone 4 . Alkaline saponification gives the 2-hydroxy-benzophenone 8 , whereas heating with hydrochloric acid causes a selective cleavage of the acetoxy group to the 2-hydroxy-thiobenzophenone 7 .     

Pyryliumverbindungen. XVIII, 2-Alkoxy-2H-pyrane aus tetra- und pentasubstituierten Pyryliumsalzen

Pyrylium Compounds. XVIII. 2-Alkoxy-2H-pyrans from Tetra- and Pentasubstituted Pyrylium Salts Alkali alkoxides add regioselectively to 2,3,4,6-tetrasubstituted pyrylium salts 7 (R' H), affording high yields of colourless crystalline 2-alkoxy-2H-pyrans 9 . The latte are also formed simply on refluxing 7 in the corresponding alcohol with triethylamine as proton acceptor. 3,5-Dialkylsubstituted 2,4,6-triarylpyrylium salts react analogously. The 2H-pyran structure of the adducts obtained follows from their n.m.r., i.r., u.v. and mass spectra as well as from their reaction with tetracyanoethylene to cycloadducts of type 10 . Acids regenerate from 9 the original pyrylium cations, whereas reaction of 9 with nitromethane or ethyl cyanoacetate provides benzene derivatives. -- The novel starting pyrylium salts 7b--o are characterized by u.v./vis data and by transformation into the corresponding pyridine derivatives     

Pyryliumverbindungen. 37. Arylbenzene aus 2,4,6-Triaryl-pyryliumsalzen und Carbonsäureanhydriden

Pyrylium Compounds. 37. Arylbenzenes from 2,4,6-Triarylpyrylium Salts and Carboxylic Acid Anhydrides Refluxing 2,4,6-triarylpyrylium salts 1 with excess carboxylic acid anhydrides (RCH₂CO)₂O ( 2a : R = H, 2b : R = Me) in the presence of condensing agents like sodium or potassium acetate, sodium carbonate or methoxide, triethylamine or pyridine results in 1,3,5-triarylbenzenes 3 (R = H, Me). Under similar conditions, phenylacetic acid anhydride ( 2c ), generated in situ from sodium phenylacetate and excess 2a or 2b , yields 1,2,3,5-tetraarylbenzenes 3 (R = Ph). Thus, the reaction 1 + 2 → 3 represents a new and simple method for replacing the pyrylium heteroatom =O^⊕– by the =CR– moiety (R = H, Me, Ph). The structure of the arylbenzenes 3 was proved by spectroscopic methods, by comparison with literature data or by independent synthesis. As by-products 2-acyloxy-benzophenones 10 are formed. Reaction of 3,5-dimethyl-2,4,6-triphenyl-pyrylium perchlorate ( 11 ) with acetic acid anhydride/sodium acetate (or sodium phenylacetate) takes another course leading to 2-acetoxy-3,5-dimethyl-4,6-diphenyl-benzophenone ( 15 ), whereas treatment of 11 with propionic acid anhydride/sodium acetate follows the reaction scheme 1 + 2 → 3 giving 1,3,5-trimethyl-2,4,6-triphenylbenzene ( 16 ). The mechanisms of the different pyrylium ring transformations are discussed.     

Untersuchungen zur Tautomerie von o,o'-Dihydroxy-azofarbstoffen der Eriochrom-Reihe

Investigations on the Tautomerism of o,o'-Dihydroxy Azo Dyes of the Eriochrome Type Investigation of the u.v.-vis-, ¹H- and ¹³C-n.m.r. spectra of the title substances and the isomers 3 and 3p at different pH-values and in different solvent mixtures as well as of O,O'-dimethyl derivatives of 2 and 3 show that in aqueous solution as well the monoanions as the trianions exist in the azo forms only. The dianions exist in dependence on the solvents as mixtures of tautomers. The results of PPP calculations for different prototropic structures are in good accordance with the experimental results.     

Pyryliumverbindungen. 31 [1]. Reaktion 3-alkylsubstituierter 2,4,6-Triaryl-pyryliumsalze mit 1,3-Diketonaten: Ein Weg zur Darstellung 3-acylsubstituierter Benzophenone

Pyrylium Compounds. 31. Reaction of 3-Alkyl-2,4,6-triarylpyrylium Salts with 1,3-Diketonates: A Method for the Preparation of 3-Acylsubstituted Benzophenones Reaction of 3-alkyl-2,4,6-triarylpyrylium salts with 1,3-diketones in the presence of one equivalent of triethylamine or potassium tert-butoxide does not lead — as originally suspected — to the primary adducts of 2H-pyran structure 6 , but to the open-chain valence isomers 7 . Treatment of the latter with one equivalent of tert-butoxide in tert-butyl alcohol gives the same 3-alkyl-2,4,6-triarylacetophenones 9 which are obtained directly from 5 , 1,3-diketones and two equivalents of potassium tert-butoxide. However, on treating 7 with aqueous ethanolic sodium hydroxide 3-acylsubstituted benzophenones 10 are formed in good yields. The reaction sequence 5→7→10 can also be performed through a one-pot-procedure. — The i.r., u.v., n.m.r. and mass spectroscopic data of the novel products 7, 9 , and 10 are reported.     

针织物平幅丝光整理

针织物丝光工艺能使针织物的性能更好.光泽度、尺寸稳定性和顶破强度的提高是针织物丝光处理的主要目的.另一优点则是提高染色效率.特别是织物的光泽、清晰和平整的外观会迎合消费者.对于消费者,即使从初次水洗开始就可明显地看出尺寸稳定性的提高.此后,还会注意到顶破强度也大大改善.最重要的是,消费者将惊喜地发现用丝光棉制成的衣服可长期保持"崭新"的外观.     

Ringöffnungs- und SubstitutionsReaktionen von 4,4-Dihalogen-pyrazolin-5-onen durch Nucleophile

Ring Opening and Substitution Reactions of 4,4-Dihalo-pyrazolin-5-ones with Nucleophiles 1-Aryl-4,4-dihalo-3-methyl-pyrazolin-5-ones ( 1a – c ) undergo ring opening with alkoxides and form alkyl 3-arylazo-2-halo-2-butenoats ( 2a – d ). Analogous reactions take place with ammonia and amines. 4-Nitro-phenoxide reacts with substitution of both halogens to the 4,4-bis(4-nitro-phenyl)-compound ( 5 ). Phenols are selectively orthobrominated by the title compounds 1a and b .     

Effect of load reduction mechanisms on loads and blade bearing movements of wind turbines

The power control of wind turbines is usually realized via a change in the pitch angle of the rotor blades. Pitching facilitates the exact control of the turbines and the reliable deceleration of the rotor when required. Pitch movements can moreover be used for load control. One of these methods is called individual pitch control (IPC). IPC controls the blades individually and brings about a significant reduction in the fatigue loads and extreme loads placed on the structural components, while at the same time reducing the yield of the turbine only slightly. The lower loads reduce material costs, and thus, the cost of energy (CoE) is reduced, despite the slight reduction in yield. The method is nevertheless not used everywhere since the additional movement cycles put the rotor blade bearings in particular under stress. Special attention must be paid to small amplitude oscillating movements, which carry a high risk of inducing surface damage in the rolling contacts of the blade bearings. This paper uses a cycle analysis of the IWT7.5‐164 reference turbine to illustrate the differences in the movement patterns of wind turbine blade bearings with and without IPC. Moreover, model calculations with single contacts are used to show which of the movement patterns carries a risk of inducing surface damage. The use of IPC leads to the expected load reduction at the blade root. In current literature, IPC is usually assumed to have a negative influence on the life expectancy of blade bearings, but the findings of this study contradict this. The summed blade bearing movement is increased, although the number of very small pitch angles occurring is reduced. This reduction reduces the risk of wear in the blade bearings.     

Correlation of Ⅲ/Ⅴ semiconductor etch results with physical parameters of high-density reactive plasmas excited by electron cyclotron resonance

Reactive ion etching is the interaction of reactive plasmas with surfaces. To obtain a detailed understanding of this process, significant properties of reactive composite low-pressure plasmas driven by electron cyclotron resonance(ECR) were investigated and compared with the radial uniformity of the etch rate. The determination of the electronic properties of chlorine-and hydrogen-containing plasmas enabled the understanding of the pressure-dependent behavior of the plasma density and provided better insights into the electronic parameters of reactive etch gases. From the electrical evaluation of I(V) characteristics obtained using a Langmuir probe,plasmas of different compositions were investigated. The standard method of Druyvesteyn to derive the electron energy distribution functions by the second derivative of the I(V)characteristics was replaced by a mathematical model which has been evolved to be more robust against noise, mainly, because the first derivative of the I(V) characteristics is used. Special attention was given to the power of the energy dependence in the exponent. In particular, for plasmas that are generated by ECR with EM modes, the existence of Maxwellian distribution functions is not to be taken as a self-evident fact, but the bi-Maxwellian distribution was proven for Ar-and Kr-stabilized plasmas. In addition to the electron temperature, the global uniform discharge model has been shown to be useful for calculating the neutral gas temperature. To what extent the invasive method of using a Langmuir probe could be replaced with the noninvasive optical method of emission spectroscopy, particularly actinometry, was investigated,and the resulting data exhibited the same relative behavior as the Langmuir data. The correlation with etchrate data reveals the large chemical part of the removal process—most striking when the data is compared with etching in pure argon. Although the relative amount of the radial variation of plasma density and etch rate is approximately ?5%, the etch rate shows a slightly concave shape in contrast to the plasma density.