cas 499-06-9, 3,5-Dimethylbenzoic acid | Articles data

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Ferric ion concentration-controlled aerobic photo-oxidation of benzylic C–H bond with high selectivity and conversion
A Fe(III)-promoted highly selective photo-oxidation of benzylic C–H bond delivering relative carbonyl products is reported. By altering the concentration of ferric salt, methylarenes can be selectively oxidized under UV irradiation to furnish aromatic aldehydes or acids, respectively. By this protocol, the oxidation of ethylarenes provides the corresponding acetophenones. The reaction is inferred to involve divergent pathways in different concentrations of catalyst for the alternative selectivity between aldehydes and aicds. The reusable catalyst, high conversion and selectivity make this oxidation a green and economic protocol for the synthesis of aromatic carbonyl compounds.
Bu, Hongzhong,Gu, Jiefan,Li, Yufeng,Ma, Hongfei,Wan, Yuting,Wu, Zheng-Guang,Zhang, Weijian,Zhou, Ying'ao,Zhu, Hongjun
(2021/07/16)

Reaction method for selectively synthesizing aromatic aldehyde or aromatic carboxylic acid
The invention provides a reaction method for selectively synthesizing aromatic aldehyde or aromatic carboxylic acid. Toluene aromatic hydrocarbon without substituent or with substituent on a benzene ring is used as a raw material, an inorganic salt of ferric iron is used as a catalyst, air or oxygen is used as an oxidizing agent, a mixed solution of acetonitrile and water is used as a solvent, theraw material is oxidized by adjusting the dosage of the catalyst to obtain aromatic aldehyde or aromatic carboxylic acid, and the aromatic aldehyde or aromatic carboxylic acid is irradiated by ultraviolet light for 10-16 hours. Aromatic carboxylic acid obtained under the condition that the dosage of the catalyst is 5-50% mol of aromatic hydrocarbon is used as a main product, wherein the use amount of the catalyst is 70-200% mol of aromatic hydrocarbon. The reaction method provided by the invention has the characteristics of atom economy and high selectivity, uses the metal iron salt with richearth content for catalysis, and has the advantages of mild conditions, recyclable catalyst and solvent and the like.
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Paragraph 0035-0036

(2020/12/05)

Cobalt-catalyzed carboxylation of aryl and vinyl chlorides with CO2
The transition-metal-catalyzed carboxylation of aryl and vinyl chlorides with CO2 is rarely studied, and has been achieved only with a Ni catalyst or combination of palladium and photoredox. In this work, the cobalt-catalyzed carboxylation of aryl and vinyl chlorides and bromides with CO2 has been developed. These transformations proceed under mild conditions and exhibit a broad substrate scope, affording the corresponding carboxylic acids in good to high yields.
Wang, Yanwei,Jiang, Xiaomei,Wang, Baiquan
supporting information
p. 14416 - 14419
(2020/12/01)

Green synthesis method of aromatic acid
The invention discloses a green synthesis method of aromatic acid. Nickel-catalyzed carbonyl insertion is carried out on aryl iodine in the presence of formate, acid anhydride, a phosphine ligand andan organic solvent by using a nickel catalyst to obtain the aromatic acid. Efficient catalytic conversion is realized by utilizing the cheap nickel catalyst, the reaction conditions are mild, and theoperation is simple.
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Paragraph 0048-0122; 0241-0245; 0271-0272

(2020/05/01)

Nickel-catalyzed carboxylation of aryl iodides with lithium formate through catalytic CO recycling
A protocol for the Ni-catalyzed carboxylation of aryl iodides with formate has been developed with good functional group compatibility for the synthesis of a variety of aromatic carboxylic acids under mild conditions. The reaction tolerates other functionalities for cross-coupling, such as aryl bromide, aryl chloride, aryl tosylate, and aryl pinacol boronate. The reaction proceeds through a carbonylation process with in situ generated carbon monoxide in the presence of a catalytic amount of acetic anhydride and lithium formate, avoiding the use of gaseous CO. The strategy of CO recycling in catalytic amounts is critical for the success of the reaction.
Fu, Ming-Chen,Fu, Yao,Shang, Rui,Wu, Ya-Nan
supporting information
p. 4067 - 4069
(2020/04/20)

Aliphatic amines modified CoO nanoparticles for catalytic oxidation of aromatic hydrocarbon with molecular oxygen
The surface modification of metal oxides using organic modifiers is a potential strategy for enhancing their catalytic performances. In this study, a hydrophobic surface amine-modified CoO catalyst with a water contact angle of 143° was fabricated. The catalyst was characterized by XRD, TGA, FT-IR, HR-TEM, and XPS. The results showed that the fabricated catalyst performed better than the hydrophilic commercial CoO nanoparticle in the process of aromatic hydrocarbon oxidation. After the amines modification, commercial CoO also became hydrophobic and improved conversion of ethylbenzene was achieved. The surface modification of CoO with amines induced the hydrophobicity property, which could serve as a reference for the design of other hydrophobic catalysts.
Liu, Meng,Shi, Song,Zhao, Li,Chen, Chen,Gao, Jin,Xu, Jie
p. 1488 - 1493
(2019/09/09)

Efficient catalytic oxidation of methyl aromatic hydrocarbon with: N -alkyl pyridinium salts
A series of N-alkyl pyridinium salts were synthesized and employed as metal-free catalyst for the selective oxidation of methyl aromatic hydrocarbon with molecular oxygen. The electronic effect of the substitutes was found to be an important factor for the catalytic performance. With the introduction of electron-donating substitute -N(CH3)2, the conversion of p-xylene and selectivity of p-toluic acid could be simultaneously increased. 1-Benzyl-4-N,N-dimethylaminopyridinium salt showed the highest catalytic activity, and 95% conversion with 84% of selectivity to p-toluic acid could be obtained for the selective oxidation of p-xylene. Several methyl aromatic hydrocarbons could all be efficiently oxidized with the reported catalyst at the absence of any metal species.
Zhang, Qiaohong,He, Honghao,Wang, Huibin,Zhang, Zhan,Chen, Chen
p. 38891 - 38896
(2019/12/11)

Assessing the effectiveness of oxidative approaches for the synthesis of aldehydes and ketones from oxidation of iodomethyl group
Owing to excellent selectivity, high yield and stability towards over-reduction and over-oxidation, one of the impressive approaches to synthesize aldehydes and ketones is the oxidation of halomethyl groups. Numerous halomethyl oxidation-based methodologies to afford aldehydes and ketones are disclosed in the literature. Mostly, chloromethyl or bromomethyl group containing substrates have been used in the literature for performing oxidation. There are negligible data available in the literature that addresses the use of iodomethyl group containing substrates for transformation to aldehydes and ketones. In this research work, 110 reactions have been carried out to construct aldehydes and ketones from oxidation of iodomethyl group in benzylic iodides and allylic iodides using numerous well-known approaches reported in the literature. The classical approaches under observation include Sommelet oxidation, Kr?hnke oxidation, sodium periodate-mediated oxidative protocol, manganese dioxide-based oxidative approach, Kornblum oxidation and Hass–Bender oxidation. The eco-friendly approaches under observation include periodic acid-based IL protocol, periodic acid in vanadium pentoxide-mediated IL method, hydrogen peroxide in vanadium pentoxide-based approach and bismuth nitrate-promoted IL technique. In this investigation, yield, recyclability, cost-effectiveness, eco-friendliness and over-oxidation are the main parameters which are under observation. Among all these investigated techniques, periodic acid-based IL protocol, periodic acid in vanadium pentoxide-mediated IL method and hydrogen peroxide in vanadium pentoxide-based approach (aka. Chunbao oxidation protocol) were found to be highly efficient due to the following reasons: these approaches (1) provide excellent yields, (2) do not lead towards over-oxidation, (3) show good recyclability, (4) demonstrate high thermal stability and negligible flammability, and (5) require no special handling.
Faisal, Muhammad,Hussain, Sarwat,Haider, Azeem,Saeed, Aamer,Larik, Fayaz Ali
p. 1053 - 1067
(2019/04/25)

Nickel-catalyzed carboxylation of aryl and heteroaryl fluorosulfates using carbon dioxide
The development of efficient and practical methods to construct carboxylic acids using CO2 as a C1 synthon is of great importance. Nickel-catalyzed carboxylation of aryl fluorosulfates and heteroaryl fluorosulfates with CO2 is described, affording arene carboxylic acids with good to excellent yields under mild conditions. In addition, a one-pot phenol fluorosulfation/carboxylation is developed.
Ma, Cong,Zhao, Chuan-Qi,Xu, Xue-Tao,Li, Zhao-Ming,Wang, Xiang-Yang,Zhang, Kun,Mei, Tian-Sheng
p. 2464 - 2467
(2019/04/10)

An efficient approach for enhancing the catalytic activity of Ni-MOF-74: Via a relay catalyst system for the selective oxidation of benzylic C-H bonds under mild conditions
Although nickel-based materials exhibit similar catalytic activity to palladium in organic synthesis, the selective oxidation of inert C-H bonds in the absence of other co-catalysts remains a largely unsolved challenge. This paper introduces a facile and efficient approach for enhancing the catalytic activity of Ni-MOF-74 with [bmim]Br via a relay catalysis strategy, which is excellent for the selective oxidation of benzylic C-H bonds. Notably, the catalyst recycling and scale up experiments demonstrated the practicability of the protocol. This method combines the catalytic advantages of MOFs and ionic liquids (ILs), and provides an insight into oxidation reactions by cheap and efficient Ni-based catalysts.
Guo, Changyan,Zhang, Yonghong,Zhang, Yi,Wang, Jide
supporting information
p. 3701 - 3704
(2018/04/17)

A method for producing 3, 5 - dimethyl benzoic acid and trimesitinic acid method
The invention discloses a method for co-producing 3,5-dimethylbenzoic acid and trimesic acid. The method comprises the steps that mesitylene is taken as raw materials and processed through first-time oxidizing, first-time separating, secondary oxidizing, secondary separating, curing and third-time separating, and then the 3,5-dimethylbenzoic acid and the trimesic acid are obtained. The method has the advantages of being simple in technology, low in cost, high in yield, good in selectivity, green and environmentally friendly.
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Paragraph 0080-0103; 0104-0115; 0116-0125; 0127-0135

(2017/08/31)

Aerobic Oxidation of Diverse Primary Alcohols to Carboxylic Acids with a Heterogeneous Pd-Bi-Te/C (PBT/C) Catalyst
Heterogeneous catalytic aerobic oxidation methods represent a near-ideal approach for the conversion of primary alcohols to carboxylic acids. Here, we report that a heterogeneous catalyst composed of Pd, Bi, and Te supported on activated carbon is highly effective for the oxidation of diverse benzylic and aliphatic primary alcohols, including 5-(hydroxymethyl)furfural (HMF) and substrates bearing heterocycles and other important functional groups. In many cases, the desired carboxylic acid product is obtained in >90% yield. Additionally, the catalyst has been demonstrated in a continuous-flow packed-bed reactor for the oxidation of benzyl alcohol, achieving near-quantitative yield while undergoing over 30 000 turnovers.
Ahmed, Maaz S.,Mannel, David S.,Root, Thatcher W.,Stahl, Shannon S.
supporting information
p. 1388 - 1393
(2017/09/22)

Oxalic acid as the: In situ carbon monoxide generator in palladium-catalyzed hydroxycarbonylation of arylhalides
An efficient palladium-catalyzed hydroxycarbonylation reaction of arylhalides using oxalic acid as a CO source has been developed. The reaction features high safety, low catalyst loading, and a broad substrate scope, and provides a safe and tractable approach to access a variety of aromatic carboxylic acid compounds. Mechanistic studies revealed the decomposition pattern of oxalic acid.
Shao, Changdong,Lu, Ailan,Wang, Xiaoling,Zhou, Bo,Guan, Xiaohong,Zhang, Yanghui
supporting information
p. 5033 - 5040
(2017/07/10)

Combined production method for substituted benzaldehyde, substituted benzyl alcohol and substituted benzoic acid
The invention discloses a combined production method for substituted benzaldehyde, substituted benzyl alcohol and substituted benzoic acid. The method comprises the following steps: (1) oxidation: a step of continuously introducing substituted toluene, a catalyst and oxygen-contained gas into an oxidation reactor and carrying out reaction so as to obtain oxidation reaction liquid; (2) hydrolyzation: a step of allowing the oxidation reaction liquid to continuously enter a hydrolysis reactor, and continuously adding water into the hydrolysis reactor and carrying out reaction so as to obtain a hydrolysis reaction mixture; (3) liquid-liquid layering: a step of layering the hydrolysis reaction mixture so as to obtain an oil phase and an aqueous phase; and (4) separation of products: a step of subjecting the oil phase to distillation so as to respectively obtain incompletely-reacted substituted toluene, substituted benzyl alcohol and substituted benzaldehyde, and subjecting the aqueous phase to cooling, crystallizing and filtering so as to obtain filtrate and substituted benzoic acid. The combined production method provided by the invention has the advantages of high raw material conversion rate, few by-products, good selectivity of target products, greenness and environmental protection.
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Paragraph 0069; 0070

(2017/01/31)

Preparation and characterization of nanosized copper (II) oxide embedded in hyper-cross-linked polystyrene: Highly efficient catalyst for aqueous-phase oxidation of aldehydes to carboxylic acids
Preparation and catalytic properties of nanosized copper (II) oxide embedded in hypercrosslinked polystyrene (HPS) were investigated in this article. The CuO@HPS nanocomposite was characterized by inductively coupled plasma optical emission spectrometry (ICP-OES), Fourier transform infrared spectroscopy (FT-IR), N2-sorption analysis, X-ray powder diffraction (XRD), energy dispersive X-ray spectroscopy analysis (EDS), and transmission electron microscopy (TEM). The TEM analysis showed that the mean diameter of the resulted particles is ~ 4 nm. The nanocomposite was found to be efficient and durable catalyst in the oxidation of aldehydes to the corresponding carboxylic acids in water. The catalyst can be recycled and reused in 4 reaction runs.
Saadati, Fariba,Khani, Neda,Rahmani, Mohammad,Piri, Farideh
p. 26 - 30
(2016/04/04)

Synchronous reactor based on reaction and separation using air oxidation of substituted toluene method for producing substituted phenyl formic acid (by machine translation)
The invention discloses a synchronous reaction and separation-based reactor utilizing air oxidizing substituted toluene method for producing substituted phenyl of formic acid, the reaction separation synchronous reactor comprises a bubbling gravity reaction tower or stirring the reaction tower and constant temperature sedimentation tower; the upper part of the gas phase area including reaction tower tower , and the reaction zone of the middle lower part of the reaction gas outlet at the top of the; reaction region of the bubbling gravity reaction tower on the tower wall is provided with a plurality of groups of alternating distribution of the gravity sedimentation plate; stirring reaction tower is provided with a stirrer within the reaction zone; the bottom of the reaction zone of the reaction tower is provided with a gas inlet and the gas distributor; the reaction tower and the constant temperature sedimentation tower through the flange connection; is arranged in the constant temperature sedimentation tower can be used for the liquid through the microporous filter plate, constant temperature sedimentation tower in a microporous filter plate is arranged at the lower part of the circulation pipeline is connected to the upper part of the reaction zone of the reaction tower; using the separated synchronization reactor device for air oxidizing substituted toluene producing substituted benzoic acid, can not only reduce the excessive reaction to the product in the reactor, to obtain the high purity product substituted benzoic acid, prevent sedimentation tower reactor is connected between the pipeline and the blockage of the circulation pipeline, but also can realize at the same time in the reaction of the substituted benzoic acid in a timely and effective separation. (by machine translation)
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Paragraph 0051; 0052

(2016/12/01)

[Ru(bpy)3]Cl2-catalyzed aerobic oxidative cleavage β-diketones to carboxylic acids under visible light irradiation
A mild and highly efficient method for the preparation of carboxylic acids is developed through a visible-light-mediated aerobic oxidative cleavage of β-diketones. This process provides a potential general, practical and scalable protocol for both laboratory synthesis and industrial production of carboxylic acids in a green manner.
Wang, Xiao-Yan,Shang, Zhen-Peng,Zha, Gao-Feng,Chen, Xiao-Qing,Bukhari, Syed Nasir Abbas,Qin, Hua-Li
supporting information
p. 5628 - 5631
(2016/11/23)

Activation and Oxidation of Mesitylene C-H Bonds by (Phebox)Iridium(III) Complexes
A pincer iridium(III) complex, (Phebox)Ir(OAc)2OH2 (1) (Phebox = 3,5-dimethylphenyl-2,6-bis(oxazolinyl)), selectively cleaves the benzylic C-H bond of mesitylene to form an isolable iridium mesityl complex, (Phebox)Ir(mesityl)(OAc) (3), in >90% yield. The trifluoroacetate analogue, (Phebox)Ir(OCOCF3)2OH2 (2), was synthesized to compare with complex 1 for C-H activation, and (Phebox)Ir(mesityl)(OCOCF3) (4) was synthesized by ligand exchange of complex 3. Both complexes 1 and 2 catalyze H/D exchange between mesitylene and D2O at 180 °C, exclusively at the benzylic position; 2 gave a higher turnover number (11 TO) than 1 (6 TO) in 12 h. Using d4-acetic acid as the source of deuterium, up to 92 turnovers of benzylic H/D exchange of mesitylene were obtained with complex 1. (Phebox)Ir(OCOCF3)2OH2 catalyzed the benzylic C-H oxidation of mesitylene using Ag2O as a terminal oxidant at 130 C, to form 3,5-dimethylbenzaldehyde and 3,5-dimethylbenzoic acid in 35% ± 4% yield (5.1 ± 0.6 TO). DFT calculations were used to investigate two possible pathways for the catalytic oxidation of mesitylene: (1) C-H activation followed by oxy-functionalization and (2) Ir-oxo formation followed by outer-sphere C-H hydroxylation. Results of calculations of the C-H activation pathway appear to be the more consistent with the experimental observations. (Chemical Equation Presented).
Zhou, Meng,Johnson, Samantha I.,Gao, Yang,Emge, Thomas J.,Nielsen, Robert J.,Goddard, William A.,Goldman, Alan S.
supporting information
p. 2879 - 2888
(2015/06/30)

Ligand-Free Palladium-Catalyzed Hydroxycarbonylation of Aryl Halides under Ambient Conditions: Synthesis of Aromatic Carboxylic Acids and Aromatic Esters
Aryl halides were readily converted into their corresponding aromatic carboxylic acids in high yields with high selectivity by ligand-free palladium-catalyzed hydroxycarbonylation at room temperature and atmospheric pressure. The new method is operationally simple and scalable. In addition, aromatic esters were easily synthesized through one-pot hydroxycarbonylation/alkylation with alkyl halides.
Han, Wei,Jin, Fengli,Zhou, Qing
p. 1861 - 1868
(2015/06/30)

A Strained Disilane-Promoted Carboxylation of Organic Halides with CO2 under Transition-Metal-Free Conditions
By using a strained four-membered ring disilane (3,4-benzo-1,1,2,2-tetraethyldisilacyclobutene) and CsF, a wide range of aryl, alkenyl, alkynyl, benzyl, allyl, and alkyl halides was successfully carboxylated under an ambient CO2 atmosphere (CO2 balloon) at room temperature within 2 h. In this carboxylation, a highly reactive silyl anion, which is generated from the disilane and CsF, is a key to facilitating the formation of a carbanion equivalent. The resulting anionic species can be trapped with CO2 to produce carboxylic acids with high efficiency.
Mita, Tsuyoshi,Suga, Kenta,Sato, Kaori,Sato, Yoshihiro
supporting information
p. 5276 - 5279
(2015/11/18)

Direct carboxylation of simple arenes with CO2 through a rhodium-catalyzed C-H bond activation
Direct carboxylation of simple arenes under atmospheric pressure of CO2 is achieved through a rhodium-catalyzed C-H bond activation without the assistance of a directing group. Various arenes such as benzene, toluene, xylene, electron-rich or electron-deficient benzene derivatives, and heteroaromatics are directly carboxylated with high TONs. This journal is
Suga, Takuya,Mizuno, Hajime,Takaya, Jun,Iwasawa, Nobuharu
supporting information
p. 14360 - 14363
(2015/02/19)

Inclusion complex containing epoxy resin composition for semiconductor encapsulation
The invention is an epoxy resin composition for sealing a semiconductor, including (A) an epoxy resin and (B) a clathrate complex. The clathrate complex is one of (b1) an aromatic carboxylic acid compound, and (b2) at least one imidazole compound represented by formula (II): wherein R2 represents a hydrogen atom, C1-C10 alkyl group, phenyl group, benzyl group or cyanoethyl group, and R3 to R5 represent a hydrogen atom, nitro group, halogen atom, C1-C20 alkyl group, phenyl group, benzyl group, hydroxymethyl group or C1-C20 acyl group. The composition has improved storage stability, retains flowability when sealing, and achieves an effective curing rate applicable for sealing delicate semiconductors.
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(2014/03/21)

Iridium-catalyzed aerobic oxidation of alkylarenes with excellent turnover numbers
A highly efficient catalyst system has been developed for the aerobic oxidation of alkylarenes under solvent free conditions. The combination of iridium complex, nitrogen ligand and iodobenzene was found to be crucial for catalytic activity. Excellent turnover numbers were achieved for the preparation of benzoic acids and aryl ketones. This finding may provide useful clues for improving commercially important oxidation processes.
Yan, Yunyun,Chen, Yanyan,Yan, Ming,Li, Xingshu,Zeng, Wei
p. 64 - 67
(2013/05/08)

A reusable palladium(II)/cationic 2, 2-bipyridyl catalytic system for hydroxycarbonylation of aryl iodides in water
A water-soluble palladium(II)/cationic 2, 2′-bipyridyl system was utilized to catalyze hydroxycarbonylation of aryl iodides in the presence of a pressurized CO atmosphere under a basic aqueous solution at 100 °C. The residual aqueous solution could be reused in several times with only a slight decrease in catalytic activity. Thus, it reduced wastage of the precious metal in the reaction. A variety of aromatic carboxylic acids could still be obtained in high yields with the catalytic amount to 0.01 mol%.
Tsai, Sheng-Wen,Huang, Shao-Hsien,Lee, Han-Sheng,Tsai, Fu-Yu
p. 769 - 772
(2013/11/06)

Copper-catalyzed carboxylation of aryl iodides with carbon dioxide
A method for carboxylation of aryl iodides with carbon dioxide has been developed. The reaction employs low loadings of copper iodide/N,N,N′, N′-tetramethylethylenediamine (TMEDA) or N,N′- dimethylethylenediamine (DMEDA) catalyst, 1 atm of CO2, dimethylsulfoxide (DMSO) or dimethylacetamide (DMA) solvent, and proceeds at 25-70 C. Good functional group tolerance is observed, with ester, bromide, chloride, fluoride, ether, hydroxy, amino, and ketone functionalities tolerated. Additionally, hindered aryl iodides such as iodomesitylene can also be carboxylated
Tran-Vu, Hung,Daugulis, Olafs
p. 2417 - 2420
(2013/10/22)

4-N,N-dimethylaminopyridine promoted selective oxidation of methyl aromatics with molecular oxygen
4-N,N-Dimethylaminopyridine (DMAP) as catalyst in combination with benzyl bromide was developed for the selective oxidation of methyl aromatics. DMAP exhibited higher catalytic activity than other pyridine analogues, such as 4-carboxypyridine, 4-cyanopyridine and pyridine. The sp3 hybrid carbon-hydrogen (C-H) bonds of different methyl aromatics were successfully oxygenated with molecular oxygen. The real catalyst is due to the formation of a pyridine onium salt from the bromide and DMAP. The onium salt was well characterized by NMR and the reaction mechanism was discussed.
Zhang, Zhan,Gao, Jin,Wang, Feng,Xu, Jie
experimental part
p. 3957 - 3968
(2012/07/27)

Remarkable effect of PEG-1000-based dicationic ionic liquid for N-Hydroxyphthalimide-catalyzed aerobic selective oxidation of alkylaromatics
PEG 1000-based functional dicationic acidic ionic liquid (PEG 1000-DAIL) was used for the first time as the reaction solvent for the N-Hydroxyphthalimide (NHPI)-cobalt acetate(Co(OAc)2) catalyzed aerobic oxidations of alkylaromatics to the corresponding acids. It enhanced the efficient catalytic ability of NHPI: 99.9 % conversion of toluene with 99.5 % selectivity for benzoic acid could be obtained at 80 °C in 10 h and ethylbenzene was selectively oxidized to benzoic acid. Several alkylaromatics were efficiently oxidized to their corresponding acids under mild conditions. For substituted toluene, the conversions of substrates and the selectivity of products was affected by the position and kind of substituted groups, respectively. Both the catalyst and PEG1000-DAIL could be reused at least eight times without significantly decreasing the catalytic activity.
Lu, Tingting,Lu, Ming,Yu, Wang,Liu, Zhongjie
p. 277 - 282
(2013/01/15)

Method for estimating SN1 rate constants: Solvolytic reactivity of benzoates
Nucleofugalities of pentafluorobenzoate (PFB) and 2,4,6-trifluorobenzoate (TFB) leaving groups have been derived from the solvolysis rate constants of X,Y-substituted benzhydryl PFBs and TFBs measured in a series of aqueous solvents, by applying the LFER equation: log k = sf(Ef + Nf). The heterolysis rate constants of dianisylmethyl PFB and TFB, and those determined for 10 more dianisylmethyl benzoates in aqueous ethanol, constitute a set of reference benzoates whose experimental ΔG ? have been correlated with the ΔH? (calculated by PCM quantum-chemical method) of the model epoxy ring formation. Because of the excellent correlation (r = 0.997), the method for calculating the nucleofugalities of substituted benzoate LGs have been established, ultimately providing a method for determination of the SN1 reactivity for any benzoate in a given solvent. Using the ΔG? vs ΔH? correlation, and taking sf based on similarity, the nucleofugality parameters for about 70 benzoates have been determined in 90%, 80%, and 70% aqueous ethanol. The calculated intrinsic barriers for substituted benzoate leaving groups show that substrates producing more stabilized LGs proceed over lower intrinsic barriers. Substituents on the phenyl ring affect the solvolysis rate of benzhydryl benzoates by both field and inductive effects.
Matic, Mirela,Denegri, Bernard,Kronja, Olga
supporting information
p. 8986 - 8998,13
(2012/12/12)

A heterogenized vanadium oxo-aroylhydrazone catalyst for efficient and selective oxidation of hydrocarbons with hydrogen peroxide
A hydrazone Schiff base ligand derived from salicylaldehyde and benzhydrazide has been synthesized and reacted with vanadium(IV) leading to the corresponding vanadium(V) complex. The complex has been anchored on the surface of functionalized silica gel by N,O-coordination to the covalently Si-O bound modified salicylaldiminato ligand. The supported complex has been evaluated as a catalyst for hydrocarbon oxidation with hydrogen peroxide in acetonitrile. The heterogeneous system proved to be an efficient catalyst and was able to activate hydrogen peroxide toward the oxidation of alkenes, alkanes, benzene, and alkylaromatic compounds with more than 2,500 h-1 activity. Springer Science+Business Media B.V. 2011.
Monfared, Hassan Hosseini,Abbasi, Vahideh,Rezaei, Adineh,Ghorbanloo, Massomeh,Aghaei, Alireza
experimental part
p. 85 - 92
(2012/08/28)

Copper-catalyzed aerobic oxidative synthesis of aromatic carboxylic acids
A simple, practical and efficient copper-catalyzed method for synthesis of aromatic carboxylic acids has been developed. The protocol uses inexpensive CuI/l-proline as the catalyst/ligand, and readily available aryl halides and malononitrile as the starting materials, and the corresponding aromatic carboxylic acids were obtained in moderate to good yields. The method is of tolerance towards functional groups in the substrates.
Yang, Daoshan,Yang, Haijun,Fu, Hua
supporting information; experimental part
p. 2348 - 2350
(2011/03/21)

A synthetic approach to a molecular crank mechanism: Toward intramolecular motion transformation between rotation and translation
A molecular crank mechanism that enables transformation between rotational and translational motions was designed and synthesized. This molecule consists of a molecular ball bearing as the rotational part in which two disk-shaped rotors can rotate relative to each other through ligand exchange and flipping motion, and a [2]rotaxane as a translational part in which an axle molecule can move back-and-forth through the cavity of a crown ether-based macrocycle. 1H NMR analysis revealed that these two motions influence each other.
Okuno, Erika,Hiraoka, Shuichi,Shionoya, Mitsuhiko
supporting information; experimental part
p. 4107 - 4116
(2010/07/04)

Polyethylene glycol radical-initiated benzylic C-H bond oxygenation in compressed carbon dioxide
The PEG radical originating from the thermal/oxidative degradation of PEG in dense CO2 was successfully applied to the oxygenation of benzylic hydrocarbons under organic solvent-free conditions. In addition, in our study, dense CO2 could improve the oxygenation reaction.
Wang, Jin-Quan,He, Liang-Nian
experimental part
p. 1637 - 1640
(2009/12/23)

A novel, chemoselective and efficient microwave-assisted deprotection of silyl ethers with Selectfluor
A novel microwave-assisted, chemoselective and efficient method for the cleavage of silyl ethers (aliphatic and aromatic) catalyzed by Selectfluor is reported. A wide range of TBS-, TIPS-, and TBDPS-protected alkyl silyl ethers can be chemoselectively cleaved in high yield in the presence of aryl silyl ethers. The chemoselective deprotection of phenolic TBS ethers, and not the TIPS- or TBDPS-protected phenolic ethers, and the deprotection of silyl esters were also achieved under these reaction conditions. In addition, the transetherification and etherification of benzylic hydroxy groups in alcoholic solvents is observed.
Shah, Syed Tasadaque A.,Singh, Surendra,Guiry, Patrick J.
experimental part
p. 2179 - 2182
(2009/07/01)

WO3/70% TBHP/aqueous NaOH: An efficient catalytic combination for the selective oxidation of methylarenes and alkyl aryl ketones to benzoic acids
A new solvent-free, reusable catalytic combination consisting of WO 3/70% TBHP/aqueous NaOH has been described for the direct oxidation of methylarenes and acetophenones to the corresponding benzoic acids in high yields. Alkylarenes are oxidized to the corresponding aromatic ketones or benzylic alcohols depending upon whether NaOH is used or not. Wiley-VCH Verlag GmbH & Co. KGaA, 2008.
Shaikh, Tanveer Mahammad Ali,Sudalai, Arumugam
experimental part
p. 4877 - 4880
(2009/05/30)

The chemoselective and efficient deprotection of silyl ethers using trimethylsilyl bromide
An efficient and chemoselective cleavage of silyl ethers (primary, secondary and aromatic) by using catalytic quantities of trimethylsilyl bromide (TMSBr) in methanol is reported. A wide range of alkyl silyl ethers such as TBS, TIPS, and TBDPS can be chemoselectively cleaved in high yield in the presence of aryl silyl ethers. The deprotection of silyl esters was also achieved employing catalytic quantities of TMSBr. The Royal Society of Chemistry 2008.
Shah, Syed Tasadaque A.,Guiry, Patrick J.
experimental part
p. 2168 - 2172
(2009/02/01)

Aerobic oxidation of alcohols and alkylaromatics with dioxygen catalysed by N-hydroxyphthalimide with vanadium co-catalysts
[Bu4N]VO3 or a combination of vanadium complexes with chloride salts are attractive co-catalysts for oxidation reactions of organic compounds with dioxygen catalysed by N-hydroxyphthalimide. The role of the chloride additive relates to the formation of more labile six-coordinate vanadium complexes. The same effect is also observed with amines. Two catalytic systems based on NHPI/VO(acac)2 with LiCl or [Bu4N]Cl and NHPI/[Bu4N]VO3 are most effective in oxidation reactions of primary and secondary alcohols, but oxidation of alkylaromatics proceeds with conversion rates of from 14.4% in the case of toluene to 67.0% in the case of ethylbenzene and with different selectivities, dependent on the structure of the substrate. The Royal Society of Chemistry and the Centre National de la Recherche Scientifique.
Figiel,Sobczak
p. 1668 - 1673
(2008/03/30)

BISMUTH MEDIATED OXIDATIONS
The invention relates to a process for the oxidation of a substrate comprising a benzylic alkyl moiety, said process comprising incubating the substrate with a bismuth complex comprising bismuth and a ligand and a stoichiometric source of oxygen.
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Page/Page column 9-10

(2008/06/13)

Rhodium(I)-catalyzed carboxylation of aryl- and alkenylboronic esters with CO2
When the esters of arylboronic acids with 2,2-dimethylpropan-1,3-diol were treated with a catalytic amount of [Rh(OH)(cod)]2 in the presence of 1,3-bis(diphenylphosphino)propane and CsF in dioxane at 60 °C under carbon dioxide atmosphere, the benzoic acid derivatives were obtained in good yields. Reactions of alkenylboronic esters also proceeded under similar conditions to give α,β-unsaturated carboxylic acids. As these boronic esters are now easily available through coupling or direct borylation reactions, this method would be a useful method for the preparation of various functionalized aryl- and alkenyl-carboxylic acids. Copyright
Ukai, Kazutoshi,Aoki, Masao,Takaya, Jun,Iwasawa, Nobuharu
p. 8706 - 8707
(2007/10/03)

Bismuth-catalyzed benzylic oxidations with tert-butyl hydroperoxide
(Chemical Equation Presented) Oxidation of alkyl and cycloalkyl arenes with tert-butyl hydroperoxide catalyzed by bismuth and picolinic acid in pyridine and acetic acid gave the corresponding benzylic ketones (48-99%). Alternatively, oxidation of methyl arenes gave the corresponding substituted benzole acids (50-95%). Preliminary mechanistic studies were consistent with a radical mechanism rather than a bismuth(III)-bismuth(V) cycle.
Bonvin, Yannick,Callens, Emmanuel,Larrosa, Igor,Henderson, David A.,Oldham, James,Burton, Andrew J.,Barrett, Anthony G. M.
p. 4549 - 4552
(2007/10/03)

An efficient Pd(II)-based catalyst system for carboxylation of aromatic C-H bond by addition of a phosphenium salt
Addition of a phosphenium dramatically improved the reaction yields in the carboxylation of arenes by formic acid catalyzed by Pd(II). Control experiments revealed that the majority of the phosphenium triflate was converted to a mixed anhydride of phosphonic acid and formic acid (7), which however did not substitute for the phosphenium to improve the reaction yield.
Sakakibara, Ken,Yamashita, Makoto,Nozaki, Kyoko
p. 959 - 962
(2007/10/03)

Unexpected catalytic activity of N-hydroxyphthalimide combined with some co-catalyst in oxidation of organic substrates by dioxygen
The combination of N-hydroxyphthalimide and various co-catalyst affords an efficient catalytic system for the aerobic oxidation of organic substrates. Thus, acids, tertiary and quaternary ammonium salts and typical Lewis acids (e.g. BF3) are effective co-catalysts. Their role is concerned to weakness the O H bond in NIIPI via hydrogen bond formation or as the result of the donor-acceptor interaction.
Figiel,Sobczak
p. 869 - 873
(2007/10/03)

Homolytic dissociation of 1-substituted cyclohexa-2,5-diene-1-carboxylic acids: An EPR spectroscopic study of chain propagation
Hydrogen abstraction from 1-substituted cyclohexa-2,5-diene-1-carboxylic acids containing linear, branched and cyclic alkyl substituents, as well as allyl, propargyl (prop-2-ynyl), cyanomethyl and benzyl substituents, has been studied by EPR spectroscopy. For each carboxylic acid, EPR spectra of the corresponding cyclohexadienyl radicals were observed at lower temperatures, followed by spectra due to ejected carbon-centred radicals at higher temperatures. Rate constants, for release of the carbon-centred radicals from the cyclohexadienyl radicals, were determined from radical concentration measurements for the above range of substituents. The rate of cyclohexadienyl radical dissociation increased with branching in the 1-alkyl substituent and with electron delocalisation in the ejected carbon-centred radical; 3,5-and 2,6-dimethyl-substitution of the cyclohexadienyl ring led to reductions in the dissociation rate constants. Rate data for abstraction of bisallylic hydrogens from the cyclohexadienyl acids were also obtained for ethyl, n-propyl and isopropyl radicals. These results indicated a sharp drop in the rate of hydrogen abstraction as the degree of branching in the attacking radical increased. Small decreases in the hydrogen abstraction rate constants were observed for cyclohexadienes containing CO2R substituents.
Jackson, Leon V.,Walton, John C.
p. 1758 - 1764
(2007/10/03)

Catalytic selective oxidation of alkyl arenes to aryl tert. butyl peroxides with TBHP over Ru-exchanged Montmorillonite K10
A mild and efficient catalytic method for the benzylic oxidation of alkyl arenes to the corresponding tert. butyl aryl peroxides is described using a catalytic amount of reusable solid, Ru(III)-exchanged Montmorillonite K10 and 70% tert. butyl hydroperoxide (TBHP) as oxidant.
Nikalje, Milind D.,Sudalai
p. 5903 - 5908
(2007/10/03)

Oxidation catalytic system and oxidation process using the same
A substrate (e.g., a cycloalkane, a polycyclic hydrocarbon, an aromatic compound having a methyl group or methylene group adjacent to an aromatic ring) is oxidized with oxygen in the presence of an oxidation catalyst comprising an imide compound of the following formula (1) (e.g., N-hydroxyphthalimide), and a co-catalyst (except phosphovanadomolybdic acid) containing an element selected from the group consisting of Group 2A elements of the Periodic Table of Elements, transition metals (Group 3A to 7A elements, Group 8 elements, Group 1B elements and Group 2B elements of the Periodic Table of Elements) and Group 3B elements of the Periodic Table of Elements, for the formation of an oxide (e.g., a ketone, an alcohol, a carboxylic acid): STR1 wherein R1 and R2 represent a substituent such as a hydrogen atom or a halogen atom, or R1 and R2 may together form a double bond or an aromatic or nonaromatic 5- to 12-membered ring, X is O or OH, and n is 1 to 3.
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(2008/06/13)

Catalytic Oxidation of Alkylbenzenes with Molecular Oxygen under Normal Pressure and Temperature by N-Hydroxyphthalimide Combined with Co(OAc)2
A practical catalytic method to convert alkylbenzenes into the corresponding carboxylic acids under atmospheric dioxygen at ambient temperature using a combined catalytic system consisting of N-hydroxyphthalimide (NHPI) and Co(OAc)2 was developed. For instance, the oxidation of toluene was completed by NHPI combined with Co(OAc)2 under an oxygen atmosphere at room temperature to give benzoic acid in 81% yield. Under these conditions, o- and p-xylenes were selectively converted into the corresponding monocarboxylic acids without the formation of the dicarboxylic acids. ESR measurements showed that Co(II) species assists in the formation of phthalimide-N-oxyl (PINO), which is a key species in this oxidation, from NHPI.
Yoshino, Yasushi,Hayashi, Yoshiaki,Iwahama, Takahiro,Sakaguchi, Satoshi,Ishii, Yasutaka
p. 6810 - 6813
(2007/10/03)

Cr-MCM-41-Catalyzed selective oxidation of alkylarenes with TBHP
A mild and efficient catalytic method for benzylic oxidation of alkylarenes to the correspondxinxg carbonyl compounds in good yields is described using a catalytic amount of reusable solid, mesoporous chromosilicate (Cr-MCM-41) and 70% tert-butyl hydroperoxide (TBHP) as oxidant.
Das,Chaudhari,Nandanan,Chandwadkar,Sudalai,Ravindranathan,Sivasanker
p. 3631 - 3634
(2007/10/03)

Electron Transfer Activation - A Selective Photooxidation Method for the Preparation of Aromatic Adehydes and Ketones
A selective and mild photocatalytic procedure for benzylic oxydations with 9,10-dicyanoanthracene (DCA), an usual electron acceptor, in presence of methyl viologen (MV2+) and FeCl2 has been developped.Key words: Singlet Electron Transfer; benzylic oxidation; hydroperoxides
Santamaria, Jean,Jroundi, Rachid
p. 4291 - 4294
(2007/10/02)

FORMATION OF ORGANOBROMINE COMPOUNDS IN THE LIQUID-PHASE OXIDATION OF METHYLBENZENES IN PRESENCE OF A COBALT BROMIDE CATALYST SYSTEM
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Shcherbina, F. F.
p. 1188 - 1192
(2007/10/02)

Synthesis of 1,2-Di-(4-pyridyl)ethylenediamine and Related Compounds
Hydrolysis of N,N'-diacyl-1,2-di(4-pyridyl)ethylenediamines 1 in aqueous sulfuric acid gave the corresponding imidazolines 3. 1,2-Di-(4-pyridyl)ethylene diamine 2 was prepared in 61percent yield by treating N,N'-di-t-butyloxycarbonyl-1,2-di(4-pyridyl)ethylenediamine 4 with trifluoroacetic acid or in 94percent yield by the hydrolysis under basic conditions of N,N'-diphthaloylglycyl-1,2-di(4-pyridyl)ethylenediamine 13.
Brana, Miguel F.,Castellano, Jose M.,Rodriguez, Maria L. Lopez,Galvez, Magdalena,Amil, Manuel R.,Rubio, Enrique
p. 369 - 371
(2007/10/02)

PHOTO-OXYGENATION OF ALKYLBENZENES BY A PLATINUM CATALYTIC SYSTEM
Alkylbenzenes are photo-oxygenated under air bubbling at room temperature, in the presence of a PtN2S2 complex as catalyst precursor.
Monaci, Anna
p. 339 - 340
(2007/10/02)