Targeted and Systematic Approach to the Study of pKa Values of Imidazolium Salts in Dimethyl Sulfoxide

2017 ◽  
Vol 82 (14) ◽  
pp. 7324-7331 ◽  
Author(s):  
Michelle H. Dunn ◽  
Nicholas Konstandaras ◽  
Marcus L. Cole ◽  
Jason B. Harper
Keyword(s):  
Dimethyl Sulfoxide ◽  
Systematic Approach ◽  
Imidazolium Salts ◽  
Pka Values

The pKa values of N-aryl imidazolinium salts, their higher homologues, and formamidinium salts in dimethyl sulfoxide

2020 ◽  
Vol 18 (10) ◽  
pp. 1910-1917 ◽  
Author(s):  
Nicholas Konstandaras ◽  
Michelle H. Dunn ◽  
Ena T. Luis ◽  
Marcus L. Cole ◽  
Jason B. Harper
Keyword(s):  
Dimethyl Sulfoxide ◽  
Ring Size ◽  
Pka Values ◽  
Imidazolinium Salts

The effects of substitution, ring size and cyclisation on the pKa values of imidazolinium salts, higher homologues and formamidinium salts in DMSO are quantified, considering structural and electronic motifs along with crystallographic analyses.

Acid-Base Equilibria of Substituted Pyridine N-Oxides in N,N-Dimethylformamide and Dimethyl Sulfoxide

1993 ◽  
Vol 46 (2) ◽  
pp. 185 ◽  
Author(s):  
L Chmurzynski ◽  
Z Warnke
Keyword(s):  
Dimethyl Sulfoxide ◽  
Linear Relationship ◽  
Aprotic Solvent ◽  
Heterocyclic Amines ◽  
Aprotic Solvents ◽  
Acid Base ◽  
Acidity Constants ◽  
Pka Values ◽  
Weak Tendency

Acidity constants have been determined potentiometrically for a variety of conjugate acids of substituted pyridine N-oxides in N,N- dimethylformamide ( dmf ) and dimethyl sulfoxide ( dmso ). The pKa values in these solvents varied in the same direction and correlated with the pKa values of these species in water and in the protophobic aprotic solvent acetonitrile. Further, a linear relationship has been established between the pKa values in the two protophilic aprotic solvents under study. The most basic substituted pyridine N-oxides exhibited a weak tendency towards cationic homoconjugation in dmf , whereas in the more basic dmso the homoconjugation equilibrium was not established for any of the heterocyclic N-oxides. The phenomenon of cationic homoconjugation was also not observed with pyridine as a representative of heterocyclic amines, both in dmf and dmso. This finding complies with the results obtained in other polar aprotic solvents.

The SN1CB Mechanism in Non-Aqueous Solution

1988 ◽  
Vol 41 (9) ◽  
pp. 1369 ◽  
Author(s):  
WG Jackson ◽  
RL Angel
Keyword(s):  
Aqueous Solution ◽  
Dimethyl Sulfoxide ◽  
Primary Amines ◽  
Tertiary Amines ◽  
Pka Values ◽  
First Order ◽  
Rate Laws ◽  
General Base ◽  
First Order Kinetics ◽  
Conjugate Base

The reaction between (NH3)5Co-NCMe3+ and dimethyl sulfoxide (Me2SO) to produce (NH3)5Co-OSMe23+ and MeCN in Me2SO solvent is general base-catalysed. The rates and rate laws have been determined for 10 substituted amines. First-order kinetics are observed, and the rates show a dependence which is less than first order on base (B) concentration. These facts are rationalized in terms of a common, reactive conjugate base (NH3)4(NH2)CoNCMe2+, the solvolysis of which occurs at a rate competitive with its rate of reprotonation by BH+. Alternative mechanisms are considered. The measured rates, which span two orders of magnitude, do not correlate with base nucleophilicity, steric features of the amines, nor pKa values as measured for aqueous solution. Primary amines are very effective catalysts; secondary and especially tertiary amines are poorer catalysts. There appears to be no reaction at the bound nitrile function as there is in aqueous solution.

Reading Longer Words: Insights Into Multisyllabic Word Reading

2017 ◽  
Vol 2 (1) ◽  
pp. 86-94 ◽  
Author(s):  
Lindsay Heggie ◽  
Lesly Wade-Woolley
Keyword(s):  
Systematic Approach ◽  
Word Reading ◽  
Explicit Instruction ◽  
Working Memory Capacity ◽  
Reading Difficulties ◽  
Instructional Programs ◽  
Morphological Knowledge ◽  
Morphological Complexity ◽  
Reading Accuracy ◽  
Grade 3

Students with persistent reading difficulties are often especially challenged by multisyllabic words; they tend to have neither a systematic approach for reading these words nor the confidence to persevere (Archer, Gleason, & Vachon, 2003; Carlisle & Katz, 2006; Moats, 1998). This challenge is magnified by the fact that the vast majority of English words are multisyllabic and constitute an increasingly large proportion of the words in elementary school texts beginning as early as grade 3 (Hiebert, Martin, & Menon, 2005; Kerns et al., 2016). Multisyllabic words are more difficult to read simply because they are long, posing challenges for working memory capacity. In addition, syllable boundaries, word stress, vowel pronunciation ambiguities, less predictable grapheme-phoneme correspondences, and morphological complexity all contribute to long words' difficulty. Research suggests that explicit instruction in both syllabification and morphological knowledge improve poor readers' multisyllabic word reading accuracy; several examples of instructional programs involving one or both of these elements are provided.

Coming Together Through Falling Apart

2019 ◽  
Vol 40 (2) ◽  
pp. 151-168
Author(s):  
Heather Churchill ◽  
Jeremy M. Ridenour
Keyword(s):  
Data Analysis ◽  
Qualitative Data ◽  
Structural Changes ◽  
Systematic Approach ◽  
Qualitative Approach ◽  
Psychological Assessments ◽  
Transference And Countertransference ◽  
Testing Data ◽  
Psychoanalytically Oriented Psychotherapy

Abstract. Assessing change during long-term psychotherapy can be a challenging and uncertain task. Psychological assessments can be a valuable tool and can offer a perspective from outside the therapy dyad, independent of the powerful and distorting influences of transference and countertransference. Subtle structural changes that may not yet have manifested behaviorally can also be assessed. However, it can be difficult to find a balance between a rigorous, systematic approach to data, while also allowing for the richness of the patient’s internal world to emerge. In this article, the authors discuss a primarily qualitative approach to the data and demonstrate the ways in which this kind of approach can deepen the understanding of the more subtle or complex changes a particular patient is undergoing while in treatment, as well as provide more detail about the nature of an individual’s internal world. The authors also outline several developmental frameworks that focus on the ways a patient constructs their reality and can guide the interpretation of qualitative data. The authors then analyze testing data from a patient in long-term psychoanalytically oriented psychotherapy in order to demonstrate an approach to data analysis and to show an example of how change can unfold over long-term treatments.

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