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

1960 ◽  
Vol 38 (7) ◽  
pp. 1092-1098 ◽  
Author(s):  
K. U. Ingold
Keyword(s):  
Carbon Tetrachloride ◽  
Benzene Ring ◽  
Hydroxyl Group ◽  
Steric Repulsion ◽  
Substituted Phenols ◽  
Tert Butyl ◽  
Carbon Tetrachloride Solution ◽  
Butyl Group ◽  
Tert Butyl Group ◽  
Infrared Frequencies

The infrared frequencies, intensities, and apparent half band widths of the O—H stretching band of a series of 2,6-di-tert-butyl-4-substituted phenols have been measured in carbon tetrachloride solution and compared with the corresponding 4-substituted phenols. The frequencies of the former are 36 cm−1 higher than the latter and the intensities are also slightly higher. Both the frequency and intensity follow a Hammett ρσ relation. It is shown that the O—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 group.

The hydroxyl stretching frequencies and conformations of Flavan-4-ols and Thiaflavan-4-ols

1969 ◽  
Vol 22 (11) ◽  
pp. 2337 ◽  
Author(s):  
GF Katekar ◽  
AG Moritz
Keyword(s):  
Carbon Tetrachloride ◽  
Benzene Ring ◽  
Hydroxyl Group ◽  
Hydroxyl Groups ◽  
Frequency Shifts ◽  
Characteristic Frequencies ◽  
Carbon Tetrachloride Solution ◽  
Free Hydroxyl ◽  
Related Compounds

The hydroxyl stretching frequencies of some 2,4-cis and 2,4-trans flavan-4-ols, thiaflavan-4-ols, and related compounds have been measured in dilute carbon tetrachloride solution. Characteristic frequencies are observed at 3626�2 cm-1 (free hydroxyl), 3616�1, and 3597�2 cm-1. The 3616 and 3597 cm-1 bands are assigned to pseudo-axial and pseudo-equatorial hydroxyl groups respectively. Evidence is presented to show that the frequency shifts arise from differences in the interaction of the hydroxyl group with the π-electrons of the fused benzene ring, and that these flavans and thiaflavans exist in half- chair, rather than sofa conformations.

Medium-sized cyclophanes. part 51. Acylation of [2.2]metaparacyclophanes: through-space electronic interactions between two benzene rings

2000 ◽  
Vol 78 (2) ◽  
pp. 238-247 ◽  
Author(s):  
Takehiko Yamato ◽  
Kiwamu Tokuhisa ◽  
Hirohisa Tsuzuki
Keyword(s):  
Benzene Ring ◽  
Acetyl Chloride ◽  
Electrophilic Aromatic Substitution ◽  
Electronic Interaction ◽  
Aromatic Substitution ◽  
Reaction Conditions ◽  
Tert Butyl ◽  
Butyl Group ◽  
Tert Butyl Group ◽  
Sigma Complex

The acylation of 8-methyl- (1b) and 8-methoxy[2.2]metaparacyclophane 1c with 1.1 equiv. of acetyl chloride in CS2 solution in the presence of aluminum chloride afforded 15-acetyl-8-methyl- (2b) and 12-acetyl-8-methoxy[2.2]metaparacyclophanes (3c) with 65 and 41% yields, respectively. The different orientations for the electrophilic substitution were observed to be dependant on the substituent at the 8 position. On the other hand, when the same reaction was carried out under the same reaction conditions with the corresponding 5-tert-butyl derivatives (11), ipso-acetylation at the tert-butyl group was observed along with acetylation on the para-benzene ring. The substituent effect on the 8-position was also observed in the present ipso-acetylation. The ipso-acylation at the tert-butyl group of 5-tert-butyl-8-methoxy[2.2]metaparacyclophane (11c) is attributed to the highly activated character of the aryl ring and the increased stabilization of a sigma-complex intermediate arising from the dienone-type sigma-complex intermediate possible in the case of a internal methoxy substituent. However, the present ipso-acetylation has not been observed in mild reaction conditions such as acetyl chloride in the presence of TiCl4 catalyst due to deactivation of the second aromatic ring by the introduced acetyl group on the para-benzene ring. The mechanism of these novel reactions is also discussed.Key words: cyclophanes, electrophilic aromatic substitution, regioselectivity, through-space electronic interaction, ipso-acylation.

Hydroxyl stretching vibration in 2,6-dimethyl- and 2,6-dichloro-4-substituted phenols

1968 ◽  
Vol 46 (11) ◽  
pp. 1831-1833 ◽  
Author(s):  
Gordon Leary
Keyword(s):  
Carbon Tetrachloride ◽  
Band Width ◽  
Published Data ◽  
Frequency Data ◽  
Substituted Phenols ◽  
Carbon Tetrachloride Solution ◽  
Steric Factors ◽  
Stretching Vibration ◽  
Infrared Frequencies

The infrared frequencies and apparent half band widths of the O—H stretching band of a series of 2,6-dimethyl-4-substituted phenols and a series of 2,6-dichloro-4-substituted phenols have been measured in carbon tetrachloride solution. The slopes of the Hammett plots for the frequencies and half band widths of both these series are compared with those calculated from published data for 2,6-di-t-butyl-4-substituted phenols and 3- or 4-substituted phenols. Significant differences are found in ρ obtained from the frequency data for the four series. The 2,6-dimethyl-4-substituted phenols, unlike the unhindered phenols, are found to parallel the 2,6-di-t-butyl-4-substituted phenols in having a negative ρ for the frequency data and a negative ρ for the half band width correlation. It is concluded that the negative ρ from the half band widths of 2,6-di-t-butyl-4-substituted phenols is primarily a result of electronic rather than steric factors.

Medium-sized cyclophanes, part 59:1 Nitration of [3.3]- and [3.3.3]metacyclophanes — Through-space electronic interactions between two or three benzene rings

2002 ◽  
Vol 80 (2) ◽  
pp. 207-215 ◽  
Author(s):  
Takehiko Yamato ◽  
Koji Tsuchihashi ◽  
Noriko Nakamura ◽  
Mai Hirahara ◽  
Hirohisa Tsuzuki
Keyword(s):  
Acetic Anhydride ◽  
Electronic Interaction ◽  
Reaction Conditions ◽  
Tert Butyl ◽  
Mixed Acid ◽  
Butyl Group ◽  
Tert Butyl Group ◽  
Starting Compound ◽  
Nitration Product ◽  
Fuming Nitric Acid

The two tert-butyl groups of anti-6,15-di-tert-butyl-9,18-dimethoxy[3.3]metacyclophane (anti-4) are both ipso-nitrated even under mild reaction conditions such as copper(II) nitrate in an acetic anhydride solution because of the decreased deactivation of the second aromatic ring by the introduced nitro group. On the other hand, anti-5,13-di-tert-butyl-8,16-dimethoxy[2.2]metacyclophane (anti-1) undergoes replacement of only one tert-butyl group under the same reaction conditions. The higher yields of the twofold ipso-nitration product anti-7 were obtained in nitration of anti-4 with fuming nitric acid or mixed acid (HNO3–H2SO4). Thus, the number of ipso-nitrations at the tert-butyl groups of anti-4 was strongly affected by the reactivity of the nitration reagent. Nitration of the corresponding syn-conformer syn-4 with copper(II) nitrate in an acetic anhydride solution, however, led only to the recovery of the starting compound. The presently developed procedure was further applied to the direct removal of the tert-butyl group by electrophilic substitution of the larger-sized ring macrocyclic metacyclophanes, cone- and partial-cone-tri-tert-butyl[3.3.3]metacyclophanes 11.Key words: [3n]metacyclophanes, conformation, ipso-nitration, through-space electronic interaction, crystal structure.

Reactions of benzyl methyl substituted-benzyl phosphites with tert-butyl hypochlorite: "balanced TS" validating reactivity/selectivity principle

1998 ◽  
Vol 76 (6) ◽  
pp. 836-842
Author(s):  
Sung Soo Kim ◽  
Yu Zhu ◽  
In Seok Oh ◽  
Chang Gyeong Lim
Keyword(s):  
Benzyl Chloride ◽  
Activation Parameters ◽  
Differential Activation ◽  
Tert Butyl ◽  
Benzyl Chlorides ◽  
Butyl Group ◽  
Tert Butyl Group ◽  
Polar Transition ◽  
Isokinetic Relations ◽  
Selectivity Principle

Reactions of a series of several benzyl methyl substituted-benzyl phosphites with tert-butyl hypochlorite were investigated. The reactions produced phosphates, isobutene, alkyl chlorides, and benzyl chlorides via phosphonium chlorides as intermediates. Furthermore, the phosphates bearing a tert-butyl group underwent fragmentation to yield isobutene and another phosphates. Relative rates of formations of substituted benzyl and benzyl chloride (kY/kH) were measured at the temperatures (-20, 0, 20, 40°C). Logarithms of the rates (log kY/kH) were plotted against sigma + and 1/T, respectively. The former gave Hammett correlations to suggest a polar transition state (TS). The latter yielded differential activation parameters (ΔΔ Hdouble daggerY-H and ΔΔ Sdouble daggerY-H ), which indicate isokinetic relations and enthalpy control of rates. The selectivities (kY/kH) decrease with higher temperatures and thereby follow the reactivity/selectivity principle.Key words: phosphites, tert-butyl hypochlorite, Hammett correlations, differential activation terms, reactivity/selectivity principle.

Evaluation of the tert-butyl group as a probe for NMR studies of macromolecular complexes

2021 ◽  
Author(s):  
Rashmi Voleti ◽  
Sofia Bali ◽  
Jaime Guerrero ◽  
Jared Smothers ◽  
Charis Springhower ◽  
...  
Keyword(s):  
Nmr Studies ◽  
Macromolecular Complexes ◽  
Tert Butyl ◽  
Butyl Group ◽  
Tert Butyl Group

Michael addition of amines to sterically crowded ortho-benzoquinone completed with unprecedented 1,2-shift of a tert-butyl group

Tetrahedron ◽  
2021 ◽  
Vol 79 ◽  
pp. 131841
Author(s):  
Eugeny Ivakhnenko ◽  
Vasily Malay ◽  
Galina Romanenko ◽  
Oleg Demidov ◽  
Pavel Knyazev ◽  
...  
Keyword(s):  
Michael Addition ◽  
Tert Butyl ◽  
Butyl Group ◽  
Tert Butyl Group

Tri(Terf-Butyl)plumbyl-phosphanes, Synthesis and Multinuclear Magnetic Resonance

2000 ◽  
Vol 55 (10) ◽  
pp. 939-945 ◽  
Author(s):  
Max Herberhold ◽  
Christian Köhler ◽  
Volker Tröbs ◽  
Bernd Wrackmeyer
Keyword(s):  
Magnetic Resonance ◽  
Phosphorus Atom ◽  
Coupling Constants ◽  
Tert Butyl ◽  
Nmr Data ◽  
Butyl Group ◽  
Tert Butyl Group ◽  
Multinuclear Magnetic Resonance

AbstractThe reaction of tri(tert-butyl)plumbyl-lithium (1) with various phosphorus chlorides was studied. With diphenyl- and amino(phenyl)phosphorus chlorides the formation of hexa(tertbutyl) diplumbane (2) and tetraphenyldiphosphane (3) or the respective 1,2-bis(am ino)-1,2-diphenyl- diphosphanes [e. g. 5: amino = PhCH2(tBu)N] was dominant. The presence of at least one tert-butyl group at the phosphorus atom gave access to tri(tert-butyl)plumbyl-di(tert-butyl) phosphane (4) and to tri(tert-butyl)plumbyl-amino(tert-butyl)phosphanes [amino = tBu(H)N (6), Me(Ph)N (7), PhCH2(Me)N (8), PhCH2(tBu)N (9)] via the reaction of 1 with the corresponding phosphorus chlorides. Side products were again 2 and the corresponding diphosphanes, unidentified compounds, and in two cases, bis(phosphanyl)-di(tert-butyl)plumbanes [phosphanyl = tBu(H)N(tBu)P (10), Me(Ph)N(tBu)P (11)]. Trimethylplumbyl-benzyl(methyl)- amino(tert-butyl)phosphane (12) was prepared for comparison. All compounds were characterized by their 1H , 13C, 15N (9 ),31P and 207Pb NMR data. The coupling constants 1J(207Pb,31P) are large and negative, whereas the coupling constants 1J(207Pb, 13C) are small and can be of either sign. The coupling constants 2J(31P-N-13C) of 6 - 12 indicate a preferred conformation of the substituents at phosphorus and nitrogen

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