Squaraine chemistry. Synthesis of bis(4-dimethylaminophenyl)squaraine from dialkyl squarates. Mechanism and scope of the synthesis

1986 ◽  
Vol 64 (12) ◽  
pp. 2267-2273 ◽  
Author(s):  
Kock-Yee Law ◽  
F. Court Bailey
Keyword(s):  
Steric Effect ◽  
Alkyl Chain ◽  
Material Balance ◽  
Squaric Acid ◽  
Side Reactions ◽  
Key Factors ◽  
Product Analysis ◽  
Good Material ◽  
Two Factors ◽  
Optimized Conditions

The mechanism and the scope of the synthesis of bis(4-dialkylaminoaryl)squaraines from di-n-butyl squarate and N,N-dialkylanilines have been studied. Results show that water and acid are key factors of the synthesis, and these two factors have been optimized. Yields of squaraine are also found to be sensitive to the steric effect provided by the alkyl chain in dialkyl squarates as well as to the concentration of the aniline reagent used in the synthesis. Mechanistic results suggest that alkyl squarate is the precursor of the synthesis, and that squaraine is formed by diarylation of alkyl squarate with an N,N-dialkylaniline derivative. Under optimized conditions, a number of squaraines have been synthesized. Yields, which are comparable to those synthesized from squaric acid, are obtained. Product analysis with good material balance has been achieved, and results show that arylation and diarylation of the starting di-n-butyl squarate are major side reactions in the squaraine synthesis.

Determination of the Bond Dissociation Energy D(C2H5Hg—C2H5) by the Toluene Carrier Method

1971 ◽  
Vol 49 (20) ◽  
pp. 3367-3374 ◽  
Author(s):  
A. C. Lalonde ◽  
S. J. W. Price
Keyword(s):  
Excellent Agreement ◽  
Arrhenius Equation ◽  
Flow System ◽  
Material Balance ◽  
Partial Solution ◽  
Complete Analysis ◽  
Product Analysis ◽  
Good Material ◽  
Good Agreement

The pyrolysis of diethylmercury has been studied in a toluene carrier flow System from 601 to 673 °K using total pressures of 1.04 to 7.75 mm. The progress of the reaction was followed by measuring the amounts of unreacted alkyl. Partial solution of butane in the toluene condensed at the outlet of the reactor made full product analysis difficult. Complete analysis in a number of runs did yield a good material balance between alkyl decomposed and [Formula: see text].[Formula: see text][Formula: see text][Formula: see text][Formula: see text]The Arrhenius equation for reaction 1, log k1(s−1) = 15.4 − (45 700 ± 1 000)/2.3 RT, is in excellent agreement with that estimated by Benson and O'Neal. Based on a number of simplifying approximations, log k3(cm3mol−1s−1) = 10.9 − (9 300 ± 2 000)/2.3 RT. The estimated disproportionation to combination ratio, K5/K4 = 0.09 – 0.12 is in good agreement with earlier work.Approximate correction of E1 to absolute zero yields D(C2H5Hg—C2H5) = 43.7 kcal mol−1 and therefore by difference D(Hg—C2H5) = 6.5 kcal mol−1.

Phenylalanine: Its ˙OH and SO4˙⁻-Induced Oxidation and Decarboxylation. A Pulse Radiolysis and Product Analysis Study

1993 ◽  
Vol 48 (6) ◽  
pp. 761-770 ◽  
Author(s):  
Degui Wang ◽  
Heinz-Peter Schuchmann ◽  
Clemens von Sonntag
Keyword(s):  
Radical Cation ◽  
Pulse Radiolysis ◽  
Side Reactions ◽  
Intramolecular Electron Transfer ◽  
Oh Radical ◽  
Product Analysis ◽  
Water Elimination ◽  
Deprotonation Reaction ◽  
Type Radical ◽  
Radical Yield

Phenylamine has been oxidized by radiolytically generated hydroxyl and sulfate radicals, the ensuing intermediates and their reactions have been studied by pulse radiolysis and product analysis in the absence and presence of oxidants such as Fe(CN)63- and O2. Upon OH radical attack, hydroxycyclohexadienyl-type radicals are mainly formed while Η-abstraction reactions can be neglected. In the presence of Fe(CN)63- these radicals are for the most part oxidized to the corresponding tyrosines (80%), except for the ipso-OH-adduct radicals (≈ 20%). It is concluded that ˙OH-addition is almost random, but with a slight avoidance of the metaposition relative to the ortho-, para- and ipso-positions. Oxygen adds reversibly to the OH-adduct radicals (kf = 1.8 × 108 dm3 mol-1 s-1, kr = 5.4 × 104 s-1). In this case, tyrosine formation occurs by HO2˙-elimination. However, due to side reactions, tyrosine formation only reaches 52% of the OH radical yield. The tyrosine yield drops to 10% in the absence of an oxidant.Upon SO4˙⁻-attack, decarboxylation becomes a major process (33% of SO4˙⁻) alongside the production of tyrosines (43%). Here, with Fe(CN)63- as the oxidant the formation of p-Tyr (18.5%) and m-Tyr (16.5%) is preferred over o-Tyr formation (8.5%). It is believed that in analogy to other systems a radical cation is formed immediately upon SO4˙⁻-attack which either reacts with water under the formation of hydroxycyclohexadienyl-type (“OH-adduct”) radicals, or decarboxylates after intramolecular electron transfer. The radical cation can also arise indirectly through H+-catalysed water elimination from the ˙OH-adduct radicals. At pH 2 and a dose rate of 0.0046 Gy s-1 CO2 formation matches the OH radical yield when ˙OH is the attacking radical. Below pH 2, G(CO2) decreases with falling pH. This indicates the occurrence of another, unimolecular, pathway under these conditions competing effectively with decarboxylation. This appears to be a relatively slow deprotonation reaction of the carboxylprotonated phenylalanine radical cation which gives rise to the benzyl-type radical.

scholarly journals Using a Novel Grey DANP Model to Identify Interactions between Manufacturing and Logistics Industries in China

2018 ◽  
Vol 10 (10) ◽  
pp. 3456 ◽  
Author(s):  
Peng Jiang ◽  
Yi-Chung Hu ◽  
Ghi-Feng Yen ◽  
Hang Jiang ◽  
Yu-Jing Chiu
Keyword(s):  
Manufacturing Industry ◽  
Multiple Criteria Decision Making ◽  
Value Added ◽  
Manufacturing Industries ◽  
Direct Influence ◽  
Key Factors ◽  
Logistics Industry ◽  
Influence Matrix ◽  
Factors Affecting ◽  
Two Factors

As a crucial part of producer services, the logistics industry is highly dependent on the manufacturing industry. In general, the interactive development of the logistics and manufacturing industries is essential. Due to the existence of a certain degree of interdependence between any two factors, interaction between the two industries has produced a basis for measurement; identifying the key factors affecting the interaction between the manufacturing and logistics industries is a kind of decision problem in the field of multiple criteria decision making (MCDM). A hybrid MCDM method, DEMATEL-based ANP (DANP) is appropriate to solve this problem. However, DANP uses a direct influence matrix, which involves pairwise comparisons that may be more or less influenced by the respondents. Therefore, we propose a decision model, Grey DANP, which can automatically generate the direct influence matrix. Statistical data for the logistics and manufacturing industries in the China Statistical Yearbook (2006–2015) were used to identify the key factors for interaction between these two industries. The results showed that the key logistics criteria for interaction development are the total number of employees in the transport business, the volume of goods, and the total length of routes. The key manufacturing criteria for interaction development are the gross domestic product and the value added. Therefore, stakeholders should increase the number of employees in the transport industry and freight volumes. Also, the investment in infrastructure should be increased.

Uncertainty Is Inherent in Science

Uncertainty ◽  
2019 ◽  
pp. 149-165
Author(s):  
Kostas Kampourakis ◽  
Kevin McCain
Keyword(s):  
Nature Of Science ◽  
Climate Science ◽  
Natural Phenomena ◽  
Key Factors ◽  
Scientific Methods ◽  
Absolute Certainty ◽  
Two Factors

At times people seem to have a mythical view of science as an infallible source of absolute certainty. Despite the prevalence of such a view, it is deeply misguided. All science is inherently uncertain. Two key factors that contribute to science’s inherent uncertainty are the complexity of natural phenomena and human limitations. Although the challenges posed by these two factors can be somewhat mitigated by way of scientific methods of investigation and the use of precise mathematical formulations, neither can be fully done away with. As a result, all science, no matter how precise or careful the methods it employs, is inherently uncertain. This is important to realize not only for truly understanding the nature of science, but also for appreciating that pointing out uncertainties that exist in domains like climate science, evolution, and vaccination in no way undercuts their claims to being legitimate, trustworthy science.

Experimental Study on Pedestrians' Perception of Human-Induced Vibrations of Footbridges

2018 ◽  
Vol 18 (10) ◽  
pp. 1850116 ◽  
Author(s):  
Rujin Ma ◽  
Lu Ke ◽  
Dalei Wang ◽  
Airong Chen ◽  
Zichao Pan
Keyword(s):  
Experimental Studies ◽  
Shaking Table ◽  
Key Factors ◽  
Crucial Issue ◽  
Lateral Vibrations ◽  
Acceleration Amplitude ◽  
Vibration Serviceability ◽  
People’S Perception ◽  
Two Factors ◽  
Comfort Criteria

Owing to the slenderness and lightness of most modern footbridges, vibration serviceability assessment becomes a crucial issue in the design process. As one of the key factors, the vibration comfort criterion has an important influence on the assessment of the final result. However, there is an obvious lack of experimental studies in this field, especially regarding the pedestrians' perception of the induced vibrations. In this study, an experiment was conducted to investigate the pedestrians' perception of human-induced vibrations of footbridges. During the experiment, the subjects walked on a pathway that was mounted on top of a shaking table. By imposing sinusoidal excitations with different amplitudes and frequencies, the experiment aimed to determine the influence of the two factors on the walking people's perception. Based on the data collected, perception scales were proposed for both the vertical and lateral vibrations of the footbridge. The established scales comprise five levels that depend on the acceleration amplitude and the frequency. Finally, a comparison between the proposed scales, existing comfort criteria in the literature and international codes was carried out.

Running Uphill: Political Opportunity in Non-democracies

2003 ◽  
Vol 2 (4) ◽  
pp. 605-629 ◽  
Author(s):  
Cristina Corduneanu-Huci ◽  
Maryjane Osa
Keyword(s):  
Social Networks ◽  
High Risk ◽  
Sufficient Conditions ◽  
Political Opportunity ◽  
Key Factors ◽  
Media Access ◽  
Qualitative Comparison ◽  
Two Factors ◽  
Parsimonious Model

AbstractThis study analyzes twenty-four cases of occurrence/non-occurrence of mobilization in non-democratic states to determine conditions of political opportunity in high-risk authoritarian contexts. Ragin's (1987) Boolean method of qualitative comparison (QCA 3.0) is used to identify specific configurations of conditions that constitute political opportunity in non-democracies. We find that political opportunity is sensitive to conditions created by divided elites, changes in repression, media access, influential allies, and social networks. Our analysis identifies four configurations that create an opening for mobilization under authoritarian conditions. The key factors, identified by QCA in the most parsimonious model, are media access and social networks. These two factors are sufficient conditions for producing mobilization in non-democratic states.

THE RADIOLYSIS OF ETHANOL: I. VAPOR PHASE

1961 ◽  
Vol 39 (9) ◽  
pp. 1836-1842 ◽  
Author(s):  
J. M. Ramaradhya ◽  
G. R. Freeman
Keyword(s):  
Carbon Monoxide ◽  
Vapor Phase ◽  
Material Balance ◽  
Ethanol Vapor ◽  
Reaction Products ◽  
Marked Contrast ◽  
Single Product ◽  
Good Material ◽  
Alpha Radiolysis ◽  
Methane Carbon

The alpha radiolysis of ethanol vapor at 108 °C produced hydrogen as the major single product, with smaller amounts of methane, carbon monoxide, ethylene, ethane, acetaldehyde, formaldehyde, water, 2,3-butanediol, 1,2-propanediol, propanol, and butanol. The initial yield of hydrogen was G(H2) = 8.9 ± 0.4, which is much higher than the values reported for the liquid phase (G(H2) ≈ 4).A mechanism is proposed to account for the formation of the products. However, the observed value of G(H2O) = 5.4 is over four times larger than can be explained by the mechanism.There is a good material balance in the observed reaction products, which indicates that little polymerization occurred during the radiolysis. This is in marked contrast with the vapor phase radiolysis of cyclohexane.

scholarly journals Assessing causes and associated water levels for an urban flood using hydroinformatic tools

2019 ◽  
Vol 22 (1) ◽  
pp. 61-76 ◽  
Author(s):  
J. L. S. Pinho ◽  
L. Vieira ◽  
J. M. P. Vieira ◽  
S. Venâncio ◽  
N. E. Simões ◽  
...  
Keyword(s):  
River Flow ◽  
Warning System ◽  
Water Levels ◽  
Flood Event ◽  
Flood Events ◽  
Key Factors ◽  
Hydrodynamic Models ◽  
Urban Flood ◽  
River Stretch ◽  
Two Factors

Abstract Flood events are dependent on meteorological conditions but also depend on several other factors that are case specific, with relevance for reservoir operation. Hydrological and hydrodynamic models are valuable tools for understanding complex river hydrodynamics during flood events. These tools have been applied to improve understanding of the causes for an urban flood event that occurred between 9 and 11 January 2016 in the Mondego river basin, at Coimbra city (Portugal). Seven different factors that can, independently, influence the river flow at the study site were identified: three of them can be associated with the operational discharge schemes of the three upstream dams; two factors with the runoff flows from uncontrolled contributing sub-basins; another one related to discharge measurement uncertainty at a downstream dam; and finally, the seventh studied factor was sedimentation occurring in the main channel of the flooded river stretch. Hydroinformatic tools were applied in different scenarios allowing the characterization and identification of each one of the identified key factors responsible for the flood event. A proposal for a flood early warning system is presented based on the knowledge resulting from the studied flood event.

Key Factors to Prepare Polyelectrolytes Showing Temperature-Sensitive Lower Critical Solution Temperature-type Phase Transitions in Water

2012 ◽  
Vol 65 (1) ◽  
pp. 91 ◽  
Author(s):  
Yuki Kohno ◽  
Hiroyuki Ohno
Keyword(s):  
Phase Transition ◽  
Lower Critical Solution Temperature ◽  
Alkyl Chain ◽  
Alkyl Chain Length ◽  
Phase Behaviour ◽  
Solution Temperature ◽  
Temperature Sensitive ◽  
Key Factors ◽  
Critical Solution Temperature ◽  
Type Phase

Tetrabutylphosphonium styrenesulfonate and its homopolymer showed a lower critical solution temperature-type phase transition in water. As the hydrophobicity of these monomeric and polymeric salts affects phase behaviour, the phase transition temperature of the polyelectrolyte was changed by the introduction of monomers having different alkyl chain length on the phosphonium cations.

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