Infrared Intensities And Molecular Structure

Brown, Theodore L.

doi:10.1021/cr50021a005

Cited by 79 publications

(20 citation statements)

References 52 publications

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“…In Fig. 2 the intensities relative to pheilol aild to 2,6-di-tert- butyl phenol have been plotted against u. I t is obvious that a good straight line call be obtainecl without the necessity of plotting log .-I against u (4,11). With regards to the deter~lli~latio~l of band intensities, Ramsay (10) has suggested a simple formula for computing the true intensity i l l terms of the observed peak absorbance ancl apparent half band width.…”

Section: Resultsmentioning

confidence: 99%

THE INFRARED FREQUENCIES AND INTENSITIES OF THE HYDROXYL GROUP IN 2,6-DI-tert-BUTYL-4-SUBSTITUTED PHENOLS

Ingold¹

1960

Can. J. Chem.

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The infrared frequencies, intensities, and apparent half band widths of the 0-H stretching band of a series of 2,6-di-terl-buty1-4-s~1bstituted phe~lols have bcen measured in carbon tetrachloride solution and compared with the corresponding 4-substituted phenols. The freq u e~~c i e s of the former are 36 cm-I higher than the latter and the intensities are also slightly higher. Both the frequency and intensity follow a Harnnlett p u relation. I t is shown that the 0-H bond lies in the plane of the benzene ring, the increase in frequency and intensity being ascribed to a steric repulsion of the phenolic hydrogen by the adjacent tert-butyl g r o~~p . INTRODUCTIONPrevious work on the frequencies and intensities of the hydroxyl group of substituted phenols has dealt mainly with meta-and para-monosubstitution (1, 2, 3, 4), although some work has been done on the effects of orthosubstituents (5) and the frequencies of a few 2,6-di-tert-butyl phenols have been measured, but not with high precision (6, 7).The present work was devoted mainly to the changes in frequency, intensity, and half band width produced by various 4-substituents on the 0-H band in 2,6-di-tert-butyl phenols. The corresponding monosubstituted phenols were also examined. E X P E R I M E N T A LA Becliman I.R.4 spectrophotometer with lithium fluoride optics was used to measure the 0-H bands, the frequencies being calibrated by the standard absorption lines of \\later vapor. The effective slit width was about 4 cm-I. Band areas ivere obtained by graphical integration. Solution concentrations in the range 0.01-0.005 molar were employed and the cell thickness was 1.0 mm. At this concentration even the sterically non-hindered phenols show no evidence of hydrogen bonding in carbon tetrachloride.The preparation of most of the compounds employed has been described previously (8)* but the preparation of 2,6-di-tert-butyl--J--n~ethox).phenol deserves some discussion a s the present data in the literature are sonle\vhat misleading. First attempts to prepare this compound by the butylation of p-methoxyphenol in petroleum ether with isobutylene and sulphuric acid a t 50' C (9) gave, after recrystallization from n-hexane, a GOY0 yield of a product, n1.p. 103.5-104.5" C. Analysis: Found: C, 76.5; H , 10.1; CI-130, 13.4. Calculated for ClSH2402: C, 76.22; H , 10.24; C H 3 0 , 13.13. The melting point agrees with a previously reported value (6), but both the frequency and intensity of the 0-H band were much lower than expected. The required phenol has also been reported by iVIiiller and Ley (7), who prepared it from 4-rnethoxy-2,4,6-tri-tert-butyl-2,5-cyclohexadiene-1-one. Their product melted a t 106-107" and they also obtained an identical compound by the butylation of P-methoxyphenol in 84% yield, but with recrystallization from methanol.An examination of the spectrum of the raw product obtained by butylating p-~neth-oxyphenol showed two bands, the larger corresponcling t o the product already separated (m.p. 103.5-104.5) and the smaller having the frequenc...

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Section: Resultsmentioning

confidence: 99%

THE INFRARED FREQUENCIES AND INTENSITIES OF THE HYDROXYL GROUP IN 2,6-DI-tert-BUTYL-4-SUBSTITUTED PHENOLS

Ingold¹

1960

Can. J. Chem.

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“…Such empirical or semie~npirical relations give a better insight into the structure and behavior of organic ~nolecules, particularly when the chemist cannot yet disentangle the various structural factors into finer and more fundamental contributions. Considerable interest has been exhibited, in recent years, in correlating the infrared group frequencies and band intensities of related groups of organic molecules wit11 substituent constants (3)(4)(5)(6)(7)(8)(9). The infrared frequencies and intensities are contl-olled by dirferent factors.…”

Section: Introductionmentioning

confidence: 99%

“…I t is therefore important to correlate the frequencies and intensities of groups with substituent constants to ullderstand the mechanism(s) involved. Although there have been several reports of such correlatioi~s with substituent constants in the literature (3)(4)(5)(6)(7)(8)(9), there has been no systeinatic evaluation of these correlations. We have now carried out a statistical evaluation (10) of the correlations of group frecluencies and band intensities of aliphatic and benzene derivatives, in order to test the validity and utility of the correlations.…”

Section: Introductionmentioning

confidence: 99%

Correlations of Infrared Group Frequencies and Band Intensities in Organic Molecules With Substituent Constants: A Statistical Evaluation

Rao¹,

Venkataraghavan²

1961

Can. J. Chem.

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A statistical evaluation of the e~npirical linear correlations of infrared group frecl~~encies and band intensities in aliphatic and ben~ene derivatives with substituent constants has been carried out. The correlations of frequencies \\,it11 substituent constants generally give low standard deviations and acceptable correlatio~l coefficie~its, and may thus be employed for the estimatio~i of substituent constants. The correlatioi~s of band intensities with substituent constants sho\v an interesting trend of the sig11 and magnitude of the slopes ( p values) \vith the electrical property of the bond or group involi-ed in the \.ibratlon. 'The p value clecreases with the increasing electroll-n,ithcIrai\.ing power of the group.

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“…При измерении интенсивности изолированной инфракрасной полосы необходим учет влия-ния Δν β на величину истинного коэффициента поглощения в ее максимуме ) и истинное значение органических соединений является одной из самых основных задач со-временной инфракрасной спектроскопии 4 . Наиболее трудной эта задача оказывается для паров, спектры кото-рых состоят из большого числа отдельных тонких линий, далеко не всегда разрешимых с помощью обычной инфракрасной аппаратуры.…”

Section: в ж чулановскийunclassified

“…Разумеется, при этом происходит перестройка всей внешней части его электронной оболочки (образование гибридных электронных состояний). Так же происходит образование устойчивой группы (NH 4 ) + . В атоме кислорода при образовании молекулы воды также образуется гибридное состояние электронной оболочки с тетраэдрическим распределе-нием электронной плотности.…”

Section: Dwunclassified

Intensity measurements in infrared spectra

Chulanovskii¹

1959

Usp. Fiz. Nauk

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Infrared Intensities And Molecular Structure

Cited by 79 publications

References 52 publications

THE INFRARED FREQUENCIES AND INTENSITIES OF THE HYDROXYL GROUP IN 2,6-DI-tert-BUTYL-4-SUBSTITUTED PHENOLS

THE INFRARED FREQUENCIES AND INTENSITIES OF THE HYDROXYL GROUP IN 2,6-DI-tert-BUTYL-4-SUBSTITUTED PHENOLS

Correlations of Infrared Group Frequencies and Band Intensities in Organic Molecules With Substituent Constants: A Statistical Evaluation

Intensity measurements in infrared spectra

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