The Infrared Carbonyl Stretching Bands of Ring Substituted Acetophenones

Jones, Richard N.; Forbes, W. F.; Mueller, William A.

doi:10.1139/v57-071

Cited by 132 publications

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“…These data show that the carbonyl band doublet occurs in all the $-substituted benzoyl chlorides investigated. Somewhat surprisingly, although carbonyl band frequencies of ringsubstituted acetophenones showed a direct relationsl~ip with Ilammett's u values (14), no sinlilar simple relationship is obtained between these u values and either of the carbonyl band frequencies listed in Table I1 or with the arithmetic meall of the two carbonyl band frequencies. Plots of the carbonyl band frequencies against the functions u* and (a,-a'), derived by Taft, Roberts, and Moreland (15), lilcewise all failed t o show significant linearity.…”

Section: ) the Iil-isomer Would Be Eapected To Show Truo B-bandsmentioning

confidence: 84%

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Light Absorption Studies: Part Xx. The Ultraviolet Absorption Spectra and Infrared Carbonyl Bands of Benzoyl Chlorides

Forbes¹,

Myron²

1961

Can. J. Chem.

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The ultraviolet absorption spectra and infrared carbonyl bands of a number of s~~b s t i t~l t e d benzoyl chlorides are determined. It is found that as a first approximation the B-bands of the ultraviolet spectra are similar for benzoyl chlorides and for the corresponding be~~zalde-hydes and acetophenones. T h e spectra are discussed in terms of previo~~sly stated hypotheses.In this wav the order of the aDDarent nerative mesomeric effect is deduced t o be -NO. > -COCI >--CHO > -COCI~;, and theYeffective size of these substituents is confir~nid t o be in the order -NO2

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Section: ) the Iil-isomer Would Be Eapected To Show Truo B-bandsmentioning

confidence: 84%

“…ref. 14). Secondly, in m-substituted benzoyl chlorides the peal; a t lower frequel~cy is frequently more intense (cf .…”

Section: )mentioning

confidence: 99%

Light Absorption Studies: Part Xx. The Ultraviolet Absorption Spectra and Infrared Carbonyl Bands of Benzoyl Chlorides

Forbes¹,

Myron²

1961

Can. J. Chem.

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“…The models' reliability was evaluated through external validation experiments. Nine aryl/alkyl ketones (24)(25)(26)(27)(28)(29)(30)(31)(32) and three alkyl/alkyl ketones (33)(34)(35) were subjected to ATH conditions and enantiomeric ratios were subsequently determined. Using the developed models for each ketone class, predictions of enantioselectivity were made.…”

Section: Predict the Performance Of New Substratesmentioning

confidence: 99%

“…For instance, the commonly used Hammett σ value (the acidity of benzoic acid derivatives) could not be used to parameterize this library, because σ values are limited to describing electronic changes on phenyl rings at meta and para positions, also precluding description of heteroaromatic arenes and alkyl chains (23). Although σ values are too limited a descriptor for this library, these values are well correlated to carbonyl IR stretching frequencies (24,25). IR bond vibrational frequencies originate from differential charges and masses across a bond and therefore inherently describe, without limitation, carbonyl electronics and the groups bonded to the carbonyl carbon (9,18,26).…”

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Designer substrate library for quantitative, predictive modeling of reaction performance

Bess

Bischoff

Sigman

2014

Proc. Natl. Acad. Sci. U.S.A.

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Assessment of reaction substrate scope is often a qualitative endeavor that provides general indications of substrate sensitivity to a measured reaction outcome. Unfortunately, this field standard typically falls short of enabling the quantitative prediction of new substrates' performance. The disconnection between a reaction's development and the quantitative prediction of new substrates' behavior limits the applicative usefulness of many methodologies. Herein, we present a method by which substrate libraries can be systematically developed to enable quantitative modeling of reaction systems and the prediction of new reaction outcomes. Presented in the context of rhodium-catalyzed asymmetric transfer hydrogenation, these models quantify the molecular features that influence enantioselection and, in so doing, lend mechanistic insight to the modes of asymmetric induction.asymmetric catalysis | free-energy relationships | computational chemistry H uman brains are highly experienced at recognizing patterns in observed data. Organizing information and drawing connections between data enables general conclusions to be made, whether fast or slow, good or bad, or high or low. Although these qualitative assessments are routinely crafted they are subject to biases, causing evaluations to differ from one individual to another (1). The examination of a reaction's substrate scope often takes on a similarly qualitative air (2-5). A substrate scope for a developed synthetic method typically provides an indication of functional group tolerance and general trends in reaction outcomes for sterically and/or electronically varied substrates. This qualitative approach, which lacks quantitation of how substrate features will influence a reaction's outcome, particularly product selectivity, often limits a reaction's application to contexts with high degrees of similarity to the initial scope library. Additionally, it can be difficult to predict, beyond generalities such as poorly versus well-behaved, how a new substrate will perform under the reaction conditions. Addressing this limitation through quantitative prediction of reaction outcomes would significantly affect how one both develops and applies a new synthetic method while simultaneously imparting fundamental mechanistic insight (6).To accomplish this goal, an entirely new approach to examining a reaction's substrate scope is required. Because the ultimate goal is to mathematically predict a broad range of reaction outcomes, an initial library of substrates would need to be carefully designed to represent many of the impactful features influencing the reaction. Specifically, one would need to include systematic variation of steric and electronic features of a given substrate class while also limiting the initial size of the substrate library to make this a practical venture. With this in mind, the tenets of design of experiments (DoE) and regression modeling will need to be exploited, where broadly descriptive models are built from data that systematically sample the experimen...

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“…Aus (9) 10 In einer demnächst in dieser Zeitschrift erscheinenden Arbeit gehen wir auf grundsätzliche Schwierigkeiten ein, die mit der Hermitezität der yn verbunden sind. Wir werden zeigen, daß der Verzicht auf Hermitezität diese Komplikationen vermeiden läßt.…”

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Zur Axiomatik der Diracschen γ-Operatoren im Riemannschen Raum

Schmutzer¹

1962

Zeitschrift Für Naturforschung A

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The Infrared Carbonyl Stretching Bands of Ring Substituted Acetophenones

Cited by 132 publications

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Light Absorption Studies: Part Xx. The Ultraviolet Absorption Spectra and Infrared Carbonyl Bands of Benzoyl Chlorides

Light Absorption Studies: Part Xx. The Ultraviolet Absorption Spectra and Infrared Carbonyl Bands of Benzoyl Chlorides

Designer substrate library for quantitative, predictive modeling of reaction performance

Zur Axiomatik der Diracschen γ-Operatoren im Riemannschen Raum

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