Recyclable Cu/g-C_(3)N_(4)nanometric semiconductor catalyzed N-formylation of amines via photocatalytic aerobic oxidative C-C bond cleavage of aldehydes under visible-light irradiation

Due to its difficulty and complexity,the cleavage and subsequent functionalization of the C(sp^(3))-C(sp^(3))single bond has received less attention than the C-C bond formation reactions that have been extensively studied.Herein,by utilizing Cu/g-C_(3)N_(4)nanometric semiconductor as a recyclable photocatalyst,an aerobic oxidative C-C bond cleavage of aldehydes was developed with the promotion of amines under visible light irradiation.Based on the reaction,phenylacetaldehyde was selected as a highly efficient formylation reagent for amines.Under blue light irradiation,good to excellent yields of formamides were achieved for various amines in 1 atm oxygen atmosphere at room temperature.This methodology offers a practical,neutral and gentle alternative to the preparation of formamides.

Biomass valorization via electrocatalytic carbon–carbon bond cleavage

Renewable electrocatalytic upgrading of biomass feedstocks into valuable chemicals is one of the promising strategies to relieve the pressure of traditional energy-based systems.Through electrocatalytic carbon–carbon bond cleavage of high selectivity,various functionalized molecules,such as organic acids,amides,esters,and nitriles,have great potential to be accessed from biomass.However,it has merely received finite concerns and interests in the biorefinery.This review first showcases the research progress on the electrocatalytic conversion of lipid/sugar-and lignin-derived molecules(e.g.,glycerol,mesoerythritol,xylose,glucose,1-phenylethanol,and cyclohexanol)into organic acids via specific carbon–carbon bond scission processes,with focus on disclosing reaction mechanisms,recognizing actual active species,and collecting feasible modification strategies.For the guidance of further extensive studies on biomass valorization,organic transformations via a variety of reactions,including decarboxylation,ring-opening,rearrangement,reductive hydrogenation,and carboxylation,are also disclosed for the construction of similar carbon skeletons/scaffolds.The remaining challenges,prospective applications,and future objectives in terms of biomass conversion are also proposed.This review is expected to provide references to develop renewed electrocatalytic carbon–carbon bond cleavage transformation paths/strategies for biomass upgrading.

Copper-Catalyzed C-C(O)C Bond Cleavage of Monoalkylated β-Diketone: Synthesis of α,β-Unsaturated Ketones

A new and simple route for the synthesis of α,β-unsaturated ketones via cleavage of the C-C(O)C single bond of monoalkylated β-diketone has been described. The reaction was catalyzed by copper, a cheap transition metal in a weakly basic medium (K3PO4) at room temperature. To carry out this study, we first had to synthesize the monoalkylated β-diketones 1. Afterwards, α,β-unsaturated ketones 2 were obtained with high yields around 80%. Finally, all the products were characterized by 1H NMR, 13C NMR, and HRMS spectra. .

Structural and electronic effects boosting Ni-doped Mo_(2)C catalyst toward high-efficiency C-O/C-C bonds cleavage

The selective cleavage of C-O and C-C is facing a challenge in the field of catalysis.In the present work,we studied the influence of doped Ni on the structure and electronic properties,as well as the selective C-O/C-C bond cleavages in the hydrodeoxygenation of palmitic acid over Ni-Mo_(2)C catalyst.The catalytic activity on Ni doped Mo_(2)C with TOF of 6.9×10^(3)h^(-1)is much superior to intrinsic Mo_(2)C catalyst,which is also higher than most noble metal catalysts.Structurally,the doped Ni raises the active particle dispersion and the coordination numbers of Mo species(Mo-C and Mo-O),improves the graphitization degree to promote the electron transfer,and increases the amount of Lewis and Br?nsted acid,which are responsible for the excellent hydrodeoxygenation performance.The Ni promotes simultaneously C-O and C-C bonds cleavage to produce pentadecane and hexadecane owing to the increase of electron-rich Mo sites after Ni doping.These findings contribute to the understanding of the nature of Ni-doped Mo_(2)C on the roles as catalytic active sites for C-O and C-C bonds cleavage.

Ni-catalyzed carbon–carbon bonds cleavage of mixed polyolefin plastics waste

The inert carbon–carbon(C–C) bonds cleavage is a main bottleneck in the chemical upcycling of recalcitrant polyolefin plastics waste. Here we develop an efficient strategy to catalyze the complete cleavage of C–C bonds in mixed polyolefin plastics over non-noble metal catalysts under mild conditions. The nickelbased catalyst involving Ni_(2)Al_(3) phase enables the direct transformation of mixed polyolefin plastics into natural gas, and the gas carbon yield reaches up to 89.6%. Reaction pathway investigation reveals that natural gas comes from the stepwise catalytic cleavage of C–C bonds in polypropylene, and the catalyst prefers catalytic cleavage of terminal C–C bond in the side-chain with the low energy barrier.Additionally, our developed approach is evaluated by the technical economic analysis for an economically competitive production process.

Cooperative catalysis of Co single atoms and nanoparticles enables selective CAr-OCH_(3) cleavage for sustainable production of lignin-based cyclohexanols

In this work,a dual-size MOF-derived Co catalyst(0.2Co_(1-NPs)@NC)composed of single atoms(Co_(1))and highly dispersed nanoparticles(Co NPs)was prepared by in-situ Zn evaporation for the highperformance conversion of lignin-derived o-methoxyphenols(lignin oil)to cyclohexanols(up to 97%yield)via cascade demethoxylation and dearomatization.Theoretical calculations elaborated that the dual-size Co catalyst exhibited a cooperative effect in the selective demethoxylation process,in which the Co NPs could initially dissociate hydrogen at lower energies while Co1remarkably facilitated the cleavage of the C_(Ar)-OCH_(3)bond.Moreover,the intramolecular hydrogen bonds formed in the omethoxy-containing phenols were found to result in a decrease in the bond energy of the C_(Ar)-OCH_(3)bond,which was more prone to be activated by the dual-size Co sites.Notably,the pre-hydrogenated intermediate(e.g.,2-methoxycyclohexanol from guaiacol)is difficult to undergo demethoxylation,indicating that the selective C_(Ar)-OCH_(3)bond cleavage is a prerequisite for the synthesis of cyclohexanols.The 0.2Co_(1-NPs)@NC catalyst was highly recyclable with a neglect decline in activity during five consecutive cycles.This cooperative catalytic strategy based on the metal size effect opens new avenues for biomass upgrading via enhanced C-O bond cleavage of high selectivity.

Studies on a New Usage of Hypophosphorous Acid-iodine System in N-C Bond Cleavage

A mixture of hypophosphorous acid (H3PO2) and iodine in acetic acid can cleave the N-alkyl bond in a variety of N-1 substituted pyrimidine derivative in relatively high yields, without any damage to the amido bond in the non-nucleosides pyrimidine base skeleton.

COPE REARRANGEMENT INVOLVING CARBON—CARBON BOND CLEAVAGE

A new type of Cope rearrangement involving carbon-carbon bond cleavage (or de-tbutylation) was found during the heating of 4-allyl-4-methyl-2, 6-di-t-butylsemiquinone,

The Preparation of Unsymmetrical Diaminodimethylsilanes and the Cleavage of Silicon-Nitrogen Bonds by Acid Chloride

Seven unsymmetrical diaminodimethylsilanes were prepared. The reactions of these silylamine with benzoyl chloride indicated that in comparison with electronic, the steric effect played more important role on the reactivity of Si-N bond. As a new method, unsymmetrical diamide can produced by the reaction of the title compounds with diacid chloride.

β-Cyclodextrin Facilitates the Cleavage of Cobalt-Carbon Bonds during the Electrochemical Reduction of Alkylaquabis(dimethylglyoximato)Cobalt(Ⅲ)

The electrochemical reduction of alkylaquabis (dimethylglyoximato)Cobalt(Ⅲ) in the absence and presence of β-Cyclodextrin (β-CD) was inveingated by means of cylic voltammetry. It was found that β-CD facilitates the cleavage of Co-C bond during the reduchon process.

Synthesis, Characterization and Crystal Structure of a New Schiff Base Ligand from a Bis(Thiazoline) Template and Hydrolytic Cleavage of the Imine Bond Induced by a Co(II) Cation

The reaction of bis-[2-amino-4-pheny1-5-thiazolyl] disulfide with 5-nitro-salicylaldehyde in absolute ethanol resulted in the formation of a new Schiff base ligand H2L (1). Characterization of the ligand was performed by FT-IR, 1H NMR, 13C NMR, UV-Vis, elemental analysis and single crystal X-ray diffraction. The ligand, (1), possesses a disulfide –S–S– bridge of 2.1121 (3) ? length, and the molecule adopts a cis-conformation around this bond. In the crystal structure of (1), an intramolecular O–H···N hydrogen bond with D… A distance of 2.69 (3) ? was present. The reaction of (1) with Co(NO3)2·6H2O and CuCl2·2H2O in methanol afforded the corresponding metal complexes. The obtained solids were further investigated by elemental analysis and UV-Vis titration that confirmed the formation of [CoL] and [ClCuHL] complexes. However, recrystallizaion of the Co(II) complex in dimethylsulfoxide caused the complete hydrolysis of the imine bond and afforded a Co(II) complex in which two 5-nitro-salicylaldehyde and two DMSO molecules were coordinated to the central metal in an octahedral fashion. This structure (2) was also confirmed by single crystal X-ray analysis.

Catalytic transformation of cellulose and its derived carbohydrates into chemicals involving C–C bond cleavage

The catalytic transformation of cellulose, the major component of abundant and renewable lignocellulosic biomass, into building-block chemicals is a key to establishing sustainable chemical processes. Cellulose is a polymer of glucose and a lot research effort has been devoted to the conversion of cellulose to six-carbon platform compounds such as glucose and glucose derivatives through C-O bond activation. There also ex- ist considerable studies on the catalytic cleavage of C-C bonds in biomass for the production of high-value chemicals, in particular polyols and organic acids such as ethylene glycol and lactic acid. This review article highlights recent advances in the development of new catalytic systems and new strategies for the selective cleavage of C-C bonds in cellulose and its derived carbohydrates under inert, reductive and oxidative atmospheres to produce Q -Cs polyols and organic acids. The key factors that influence the catalytic performance will be clarified to provide insights for the design of more efficient catalysts for the transformation of cellulose with precise cleavage of C-C bonds to high-value chemicals. The reaction mechanisms will also be discussed to understand deeply how the selective cleavage of C-C bonds can be achieved in biomass.

Clean production of lactic acid by selective carbon-carbon bond cleavage of biomass feedstock over a novel carbon-bismuth oxychloride photocatalyst

The use of functional materials such as carbon-bismuth oxyhalides in integrated photorefineries for the clean production of fine chemicals requires restructuring.A facile biomass-assisted solvothermal fabrication of carbon/bismuth oxychloride nanocomposites(C/BiOCl)was achieved at various temperatures.Compared with BiOCl and C/BiOCl-120,C/BiOCl-180 exhibited higher crystallinity,wider visible light absorption,and a faster migration/separation rate of photoinduced carriers.For the selective C–C bond cleavage of biomass-based feedstocks photocatalyzed by C/BiOCl-180,the xylose conversion and lactic acid yield were 100%and 92.5%,respectively.C/BiOCl-180 efficiently converted different biomass-based monosaccharides to lactic acid,and the efficiency of pentoses was higher than that of hexoses.Moreover,lactic acid synthesis was favored by all active radicals including superoxide ion(·O_(2)^(−)),holes(h^(+)),hydroxyl radical(·OH),and singlet oxygen(^(1)O_(2)),with·O_(2)^(−)playing a key role.The fabricated photocatalyst was stable,economical,and recyclable.The use of biomass-derived monosaccharides for the clean production of lactic acid via the C/BiOCl-180 photocatalyst has opened new research horizons for the investigation and application of C–C bond cleavage in biomass-based feedstocks.

Enhancement of CH_(3)CO^(*) adsorption by editing d-orbital states of Pd to boost C–C bond cleavage of ethanol eletrooxidation

Improving the complete ethanol electrooxidation on Pd-based catalysts in alkaline media has drawn widely attention due to the high mass energy density.However,the weak adsorption energy of CH_(3)CO^(*) on Pd restricts the C–C bond cleavage.Inspired by the molecular orbital theory,we proposed the d-state-editing strategy to construct more unoccupied d-states of Pd for the enhanced interaction with CH_(3)CO^(*) to break C–C bonds.As expected,the reduced number of e_g electrons and more unoccupied d-states of Pd successfully formed on as-prepared porous Rh Au–Pd Cu nanosheets(PNSs).Theoretical calculations show that the optimized d-states of Rh Au–Pd Cu PNS can effectively improve the adsorption of CH_(3)CO^(*) and drastically reduce the energy barrier of C–C bond cleavage,thus boosting the complete oxidation of ethanol.The charge ratio of C_1 pathway on Rh Au–Pd Cu PNSs is 51.5%,more than 2 times higher than that of Pd NSs.Our finding provides an innovative perspective for the design of highly-efficient noble-based electrocatalysts.

The Novel Selective Reduction of the C-C Triple Bond

A novel reduction system is reported here in which the compounds with terminal C-C triple bond and disubstituted C-C triple bond react with NaBH4/Pd(PPh3)(4) in a base condition and only terminal C-C triple bond is reduced.

A NOVEL SCISSION OF ALKYL-CARBONYL C-C BOND BY ALKYL p-HYDROXYPHENYL KETONES

Methyl,ethyl,n-propyl,and benzyl p-hydroxyphenyl ketones and 6-hydroxy-1-tetralone are shown under the condition of ethylene ketal formation to undergo alkyl-carbonyl C-C bondscission,but not with p-hydroxybenzophenone,p-hydroxyisobutyrophenone,and 5-hydroxy-1-indanone.It is suggested that the scissiou is preceded by an aldol condensation.

Further Report on A Novel Scission of Alkyl Carbonyl C-C Bond by Substituted 4-Hydroxyacetophenones

3-Methoxy-, 3, 5-dimethoxy-, and 3-phenyl-4-hydroxyacetophenones suffered alkyl carbonyl C-C bond scission to yield 4-hydroxybenzoate esters and 4-isopropenylphenols under standard conditions of ethylene ketal formation; the latter underwent in situ dimerization, cyclization, and rearrangement to give substituted indanols. The isopropenylphenol derived from 3,5-ditertbutyl-4-hydroxyacetophenone did not dimerize but condensed with its precursor to yield a substituted diphenylpropanone. 3-nitro-, 3,5-dinitro-, and 3,5-dibromo-4-hydroxyacetophenones on the other hand reacted normally to give ethylene ketals in good yields.

Recent Advances of Modern Protocol for C-C Bonds—The Suzuki Cross-Coupling

Over the past 20 years, small molecule solid phase synthesis has become a powerful tool in the discovery of novel molecular materials. In the development of organic chemistry, the carbon-carbon bond formation has always been one of the most useful and fundamental reaction. The current review summarizes recent developments in metal-catalyzed coupling reactions. The following method is discussed in detail—the cross-coupling of aryl halides with aryl boronic acids (the Suzuki coupling), and the others C-C bond formation reactions as the palladium-catalyzed reaction between an aryl and (or) alkyl halide and a vinyl functionality (the Heck reaction);and the palladium-catalyzed cross-coupling reaction of organostannyl reagents with a variety of organic electrophiles (the Stille reaction)—are mentioned.

可见光催化CO_(2)参与的芳基烯烃碳碳双键断键羧基化反应

烯烃广泛存在于自然界中,在医药、农药和材料等领域具有重要应用.烯烃的C=C键断裂和转化是许多工业过程的基础,可以实现烃类资源的重组与利用.目前,C=C键参与的氧化裂解和烯烃复分解反应已有广泛的研究.相比而言,C=C键参与的还原裂解虽然是烯烃与一系列亲电试剂反应合成功能分子的重要途径,但受限于烯烃自身结构和反应特点,该过程存在较大的挑战,目前研究很少.CO_(2)具有储量丰富、廉价易得、无毒且可循环再生等优点,是合成多种大宗化学品及精细化学品的理想碳一资源.然而,CO_(2)由于热力学稳定性及动力学惰性,在温和条件下难以高效、高选择性转化.因此,利用CO_(2)参与烯烃C=C键还原裂解,选择性构建高值化合物,是一个重要且具有挑战性的研究方向.近年来,可见光催化由于具有反应条件温和、官能团兼容性高等优点,为有机合成等领域提供了新的发展机遇.本文利用二环己基甲基胺作为电子给体,成功实现了可见光催化CO_(2)参与的芳基烯烃C=C键断键羧基化反应.该反应成功的关键在于,二环己基甲基胺既能高效还原淬灭激发态光敏剂并参与烯烃的胺基烷基-羧基化反应,又不明显抑制胺基烷基化中间体对激发态光敏剂的还原淬灭.研究结果表明,多种不同取代(如给电子基和吸电子基)的芳基烯烃均可与CO_(2)发生羧基化反应,高效高选择性地构建了一系列官能团丰富的芳基乙酸类化合物(如萘普生等药物分子).该方法具有反应条件温和(1 atm,室温)、官能团耐受性好以及可用于合成药物衍生物等特点.此外,本文通过氘代实验等机理研究和密度泛函理论计算证明,胺甲基羧化中间体、苄基自由基和苄基碳负离子都是该反应的关键中间体,并提出了可能的反应机理:首先,二环己基甲基胺还原淬灭激发态光敏剂,产生α-胺基碳自由基,与芳基烯烃发生自由基加成反应,得到苄基自由基,进而被还原态光敏剂还原为碳负离子,对CO_(2)亲核进攻得到烯烃的胺基烷基-羧基化中间体;作为电子给体,该中间体可以淬灭另一分子的激发态光敏剂,并通过分子内去质子化过程,产生α-胺基碳自由基物种,进而经历自由基型β-C断裂,生成热力学更稳定的羧基化苄基自由基,从而实现了烯烃C=C键的还原裂解;最后,新产生的苄基自由基被进一步还原为碳负离子,经历质子化过程后得到目标产物.综上,本文以还原裂解的方式丰富了C=C键断键官能团化反应领域,在温和条件下实现了CO_(2)的高效高选择性转化,合成了高附加值的芳基乙酸类化合物,阐明了反应机制,为烯烃和CO_(2)的同时高值化利用提供了新思路,为后续相关反应的开发和应用提供参考.

在过渡金属催化剂上的C―C键断裂以实现生物质的升级

将当前能源生产和消费结构从过度依赖化石能源转变为高效利用可再生能源,是解决能源危机、实现碳中和的有效途径。生物质是最有前途的可再生能源之一,可以取代化石燃料以获得有价值的有机化合物。近年来,大力利用生物质能已成为一种必然趋势。用于生物质转化的传统热化学催化方法通常需要高温、高压等恶劣条件,甚至还需要外部氢或氧源。相比之下,在相对温和的条件下进行的生物质有机分子电催化转化为生产高价值化学品提供了一种绿色高效的策略。特别是,通过C―C键裂解将生物质衍生的分子转化为高价值的短链化学品至关重要。近年来,大量的研究证明过渡金属(TM)电催化剂由于其丰富的三维电子结构和独特的eg轨道增强了过渡金属-氧之间的共价键合,从而在有机物的C―C键断裂中起着至关重要的作用。此外,TM电催化剂的配位环境或电子结构会影响产物的选择性。毫无疑问,明确的反应活性位点和途径有助于深入理解催化剂结构与反应活性之间的构效关系。然而,TM电催化剂介导的生物质衍生有机分子的C―C键裂解反应用于生物质升级的研究目前尚处于起步阶段,其反应机理和催化反应过程尚不清楚。因此,有必要在原子水平上系统地了解电催化剂在C―C键裂解过程中的作用。在本综述中,我们首先依次介绍了广泛研究的TM电催化剂介导的生物质衍生有机分子(包括甘油、环己醇、木质素和糠醛)的C―C键裂解反应,并给出了一些典型的例子和相应的反应途径。然后,系统回顾了过渡金属化合物催化C―C键裂解的反应机理,揭示了界面行为,并构建了TM电催化剂的结构与裂解反应活性之间的构效关系。最后,我们简要总结了上述内容,并强调了在TM电催化剂上研究C―C键裂解的挑战和展望。我们期望这项工作可以为生物质的可控转化和合理设计C―C键裂解的TM电催化剂提供指导。