Dibenzyl Ketone Research Articles

Small-Scale Synthesis of Dibenzyl Ketone for the Organic Chemistry Teaching Laboratory

Small-Scale Synthesis of Dibenzyl Ketone for the Organic Chemistry Teaching Laboratory

Mixed Methyl/Chlorido Yttrium(III) Complexes Supported by a Neutral Tridentate N-Donor Ligand

Trimethylyttrium, supported by the neutral tridentate ligand Me3TACN (1,4,7-trimethyl-1,4,7-triazacyclononane), is readily synthesized from (Me3TACN)YCl3 (via salt metathesis with MeLi in THF) or [YMe3]n (via Me3TACN-donor addition in toluene). Such discrete complex (Me3TACN)YMe3 reacts with trimethylchlorosilane according to a silane elimination protocol, affording well-defined mixed methyl/chlorido complexes of the composition [(Me3TACN)YMe3–xClx] (x = 1, 2, 3). All complexes were characterized by X-ray diffraction, homo- and heteronuclear NMR (especially 89Y) and FTIR spectroscopies, and elemental analysis. The reaction of heteroleptic complex [(Me3TACN)YMe2Cl] with dibenzyl ketone was investigated.

Dehydrogenative Three-component Coupling of CO with Methylarenes Forming Dibenzyl Ketones

Abstract Herein reported is a photoinduced dehydrogenative three-component coupling reaction of carbon monoxide with two molecules of methylarenes forming dibenzyl ketones. A gaseous dihydrogen molecule evolves as the byproduct, and neither oxidants nor hydrogen acceptors are required.

Synthesis of 2,5-diphenyl-3,4-di(phenylethenyl)cyclopentadienone, -pyrrole and -thiophene

2,5-Diphenyl-3,4-di(phenylethenyl)cyclopentadienone (2), -pyrrole (3), and -thiophene (4) have been synthesized by bi-steps strategy. Step one involves the synthesis of cinnamil (1) by the condensation of 2,3-butanedione with benzaldehyde in the presence of Pyrrolidine as a catalyst. Step two involves the synthesis of 2,5-diphenyl-3,4-di(phenylethenyl)cyclopentadienone (2), -pyrrole (3), and -thiophene (4) by the condensation of cinnamil (1) with dibenzyl ketone, dibenzylamine, and dibenzyl sulfide, respectively in the presence of sodium hydride (base) and methylene chloride (solvent) while stirring. 1HNMR, LC-MS, IR, UV-visible, and fluorescence spectroscopy were used to confirm these products (2-4). Our method facilitated the proficient installation of four various groups on the cyclopentadienone (2), pyrrole (3), and thiophene (4) rings in two steps with an extended conjugated framework.

Deconstructive Functionalization of Ketones via an LMCT-Promoted C–C Cleavage

In this issue of Chem, Zuo and coworkers report an exciting new strategy for the deconstructive functionalization of ketones. Through merging Lewis-acid-catalyzed nucleophilic 1,2-addition and ligand-to-metal charge transfer (LMCT)-promoted C–C cleavage, common strained and unstrained ketones are transformed into synthetically valuable scaffolds with high efficiency under mild conditions.

Effects of iron-containing minerals on hydrothermal reactions of ketones

Hydrothermal organic transformations occurring in geochemical processes are influenced by the surrounding environments including rocks and minerals. This work is focused on the effects of five common minerals on reactions of a model ketone substrate, dibenzylketone (DBK), in an experimental hydrothermal system. Ketones play a central role in many hydrothermal organic functional group transformations, such as those converting hydrocarbons to oxygenated compounds; however, how these minerals control the hydrothermal chemistry of ketones is poorly understood. Under the hydrothermal conditions of 300 °C and 70 MPa for up to 168 h, we observed that, while quartz (SiO2) and corundum (Al2O3) had no detectable effect on the hydrothermal reactions of DBK, iron-containing minerals, such as hematite (Fe2O3), magnetite (Fe3O4), and troilite (synthetic FeS), accelerated the reaction of DBK by up to an order of magnitude. We observed that fragmentation products, such as toluene and bibenzyl, dominated in the presence of hematite or magnetite, while use of troilite gave primarily the reduction products, e.g., 1, 3-diphenyl-propane and 1, 3-diphenyl-2-propanol. The roles of the three iron minerals in these transformations were further explored by (1) control experiments with various mineral surface areas, (2) measuring H2 in hydrothermal solutions, and (3) determining hydrogen balance among the organic products. These results suggest the reactions catalyzed by iron oxides (hematite and magnetite) are promoted mainly by the mineral surfaces, whereas the sulfide mineral (troilite) facilitated the reduction of ketone in the reaction solution. Therefore, this work not only provides a useful chemical approach to study and uncover complicated hydrothermal organic-mineral interactions, but also fosters a mechanistic understanding of ketone reactions in the deep carbon cycle.

PH-Induced cucurbit[7]uril hydrogels: Understanding microenvironment of the aggregates through excited state reactivity of dibenzyl ketones

Abstract The supramolecular chemistry of cucurbituril aggregates arising from peripheral interactions to form hydrogels is a relatively new and less explored aspect of the cavitand family. The hydrogels formed by cucurbit[7]uril (CB7) in aqueous media is understood to consist of CB7 networks linked through C H⋯O interactions with readily manipulable material and mechanical properties, and is envisioned to contain high application potential. Therefore, understanding the microenvironmental properties of this newly emerging CB-based hydrogels is important. In this reported study we present our understanding about the microenvironmental characteristics of the CB7 hydrogels inferred from (a) the modified photoreactivity of non-C2-symmetric dibenzyl ketones (DBK) encapsulated within the hydrogels, and (b) NMR diffusion experiments. Reaction selectivity in DBK photochemistry offered insight regarding the structural integrity and effects of pH, temperature, and concentration on the aggregates, while the diffusion studies were useful in developing a qualitative idea about the equilibrium dynamics of the CB7 aggregates that constitute the hydrogels.

Trifluorination of sulfides and dithioketals using IF5-pyridine-HF

Abstract Stable fluorinating reagent, IF5-pyridine-HF, was used for the polyfluorination of aryl alkyl sulfides. The introduction of three fluorine atoms with a concomitant migration of the arylsulfanyl group was achieved. Carrying out the reaction at 80 °C and presence of a methyl substituent on the aryl group were found to be effective for the polyfluorination. Trifluorinated products were also obtained from dithioketals by reaction with IF5-pyridine-HF. Tetrafluorination of phenyl benzyl ketone and dibenzyl ketone dithioketals was also achieved by reaction with IF5-pyridine-HF and Et3N-6HF.

Iron complexes of a bidentate picolyl-NHC ligand: synthesis, structure and reactivity.

The synthesis, structure and reactivity of bidentate picolyl N-heterocyclic carbene (NHC) iron compounds were studied. Compounds [FeBr(HL)2]Br (1), [FeBr(HL)(HMDS)] (2) and [FeBr2(HL)] (3) (HL = 1-mesityl-3-(pyridin-2-ylmethyl)imidazol-1-ylidene, HMDS = hexamethyldisilazide) were prepared from H2LBr with suitable amounts of Fe(HMDS)2 or in situ prepared [Fe(HMDS)Br]. The deprotonation of 1 with 2 eq. of LiHMDS gave [FeL2] (4), featuring dearomatized pyridine moieties with exocyclic C-C double bonds. The protonation of 4 with 2 eq. of PPh3·HBr results in the formation of 1. Attempted deprotonation of 3 using benzyl Grignard as the base resulted in transmetalation products [FeBnBr(HL)] (5) and [FeBn2(HL)] (6). Exposure of 6 to CO resulted in the formation of diamagnetic compound [Fe(CO)3(HL)] (7) and dibenzyl ketone. Prolonged exposure of 7 to CO with heating induces pyridine dissociation, affording [Fe(CO)4(HL-κC)] (8). Treatment of compound 6 with an equimolar amount of p-methoxybenzyl bromide yielded homo- and cross-coupling products.

Hydrothermal photochemistry as a mechanistic tool in organic geochemistry: the chemistry of dibenzyl ketone.

Hydrothermal organic transformations under geochemically relevant conditions can result in complex product mixtures that form via multiple reaction pathways. The hydrothermal decomposition reactions of the model ketone dibenzyl ketone form a mixture of reduction, dehydration, fragmentation, and coupling products that suggest simultaneous and competitive radical and ionic reaction pathways. Here we show how Norrish Type I photocleavage of dibenzyl ketone can be used to independently generate the benzyl radicals previously proposed as the primary intermediates for the pure hydrothermal reaction. Under hydrothermal conditions, the benzyl radicals undergo hydrogen atom abstraction from dibenzyl ketone and para-coupling reactions that are not observed under ambient conditions. The photochemical method allows the primary radical coupling products to be identified, and because these products are generated rapidly, the method also allows the kinetics of the subsequent dehydration and Paal-Knorr cyclization reactions to be measured. In this way, the radical and ionic thermal and hydrothermal reaction pathways can be studied separately.

The central role of ketones in reversible and irreversible hydrothermal organic functional group transformations

Studies of hydrothermal reactions involving organic compounds suggest complex, possibly reversible, reaction pathways that link functional groups from reduced alkanes all the way to oxidized carboxylic acids. Ketones represent a critical functional group because they occupy a central position in the reaction pathway, at the point where CC bond cleavage is required for the formation of the more oxidized carboxylic acids. The mechanisms for the critical bond cleavage reactions in ketones, and how they compete with other reactions are the focus of this experimental study. We studied a model ketone, dibenzylketone (DBK), in H2O at 300°C and 70MPa for up to 528h. Product analysis was performed as a function of time at low DBK conversions to reveal the primary reaction pathways. Reversible interconversion between ketone, alcohol, alkene and alkane functional groups is observed in addition to formation of radical coupling products derived from irreversible CC and CH homolytic bond cleavage. The product distributions are time-dependent but the bond cleavage products dominate. The major products that accumulate at longer reaction times are toluene and larger, dehydrogenated structures that are initially formed by radical coupling. The hydrogen atoms generated by dehydrogenation of the coupling products are predominantly consumed in the formation of toluene. Even though bond cleavage products dominate, no carboxylic acids were observed on the timescale of the reactions under the chosen experimental conditions.

Analysis of the infrared and Raman spectra of the symmetrically substituted 1,3-diphenylurea and 1,3-diphenylacetone (dibenzyl ketone)

The structural stability of 1,3-diphenylurea and 1,3-diphenylacetone was investigated by the DFT-B3LYP and ab initio MP2 calculations using the 6-311G** basis set. From full energy optimization at the MP2 level of theory the near-planar cis–trans form of 1,3-diphenylurea was predicted to be about 1.5kcal/mol lower in energy than the X-ray near-planar cis–cis conformer. At the DFT-B3LYP level of theory the near-planar cis–trans and cis–cis forms were predicted to have a very comparable relative stability. The dibenzyl ketone was predicted by both levels to exist predominantly in a gauche–gauche conformation. On comparison the DFT near-planar structures of each of the two molecules were found to be consistent with the reported X-ray structures. The analysis of the infrared and Raman spectra of 1,3-diphenylurea suggests the presence of a second form at room temperature. The vibrational frequencies of the conformers most consistent with X-ray data of diphenylurea and dibenzyl ketone were computed at the B3LYP level and tentative vibrational assignments of their normal modes were provided on the basis of combined experimental and computed data.

Interfacial Regions Governing Internal Cavities of Dendrimers. Studies of Poly(alkyl aryl ether) Dendrimers Constituted with Linkers of Varying Alkyl Chain Length

This report deals with a study of the properties of internal cavities of dendritic macromolecules that are capable of encapsulating and mediating photoreactions of guest molecules. The internal cavity structures of dendrimers are determined by the interfacial regions between the aqueous exterior and hydrocarbon like interior constituted by the linkers that connect symmetrically sited branch points constituting the dendrimer and head groups that cap the dendrimers. Phloroglucinol-based poly(alkyl aryl ether) dendrimers constituted with a homologous series of alkyl linkers were undertaken for the current study. Twelve dendrimers within first, second, and third generations, having ethyl, n-propyl, n-butyl, and n-pentyl groups as the linkers and hydroxyl groups at peripheries in each generation, were synthesized. Encapsulation of pyrene and coumarins by aqueous basic solutions of dendrimers were monitored by UV-vis and fluorescence spectroscopies, which showed that a lower generation dendrimer with an optimal alkyl linker presented better encapsulation abilities than a higher generation dendrimer. Norrish type I photoreaction of dibenzyl ketone was carried out within the above series of dendrimers to probe their abilities to hold guests and reactive intermediate radical pairs within themselves. The extent of cage effect from the series of third generation dendrimers was observed to be higher with dendrimers having an n-pentyl group as the linker.

Synthesis of 2-oxa-6-aza-3,4-benzobicyclo-[3.3.11,5]nonane from dibenzyl ketone, salicylaldehyde, and ammonia

Synthesis of 2-oxa-6-aza-3,4-benzobicyclo-[3.3.11,5]nonane from dibenzyl ketone, salicylaldehyde, and ammonia

9-[(2-Hydroxybenzylidene)amino]-11-(2-hydroxyphenyl)-10,13-diphenyl-8-oxa-12-azoniatricyclo[7.3.1.02,7]trideca-2(7),3,5-triene acetate ethanol disolvate

The title compound, C36H31N2O3 +,C2H3O2 −·2C2H5OH, the product of a domino condensation of dibenzyl ketone with salicylic aldehyde and ammonium acetate, crystallized as the ethanol disolvate. The cation of the salt comprises a fused tricyclic system containing three six-membered rings (piperidine, dihydro-2H-pyran and benzene). The piperidine ring has the usual chair conformation, while the dihydro­pyran ring adopts a slightly distorted sofa conformation. In the crystal, there are six (one intra- and five inter­molecular) independent hydrogen-bonding inter­actions: the inter­molecular hydrogen bonds link the cations and anions and ethanol solvent mol­ecules into ribbons along [001]. The ribbons are stacked along the a axis.

Unsurpassed cage effect for the photolysis of dibenzyl ketones in water-soluble dendrimers

Amphiphilic water-soluble poly(alkyl aryl ether) dendrimers Gn (n = 1-3) with charge-neutral tetraethylene glycol monomethyl ethers at their periphery were synthesized as microreactors to control the photochemical reactions of dibenzyl ketone derivatives in aqueous solutions. Photophysical studies demonstrated that Gn can encapsulate organic molecules and provide a hydrophobic microenvironment. The product distribution of photolysis of dibenzyl ketone derivatives can be successfully controlled by encapsulating the substrates within dendrimers, and an unsurpassed cage effect of 1.00 is reached in high generation dendrimers, revealing that a thick and compact "shell" was formed at the periphery of the dendrimers. The cage effect is also significantly influenced by the substituent at the para-position of the guest molecules. The higher generation dendrimers exhibit a better confined microenvironment and the aggregates possess more compact cavities to "lock" the guests than the corresponding unimolecular dendrimers. After photolysis, the separation of products can be easily achieved by extracting from the dendrimer solutions and the dendrimers are simply recovered and reused.

ChemInform Abstract: Measurement of the Enhancement Factor of CIDNP in the Photolysis of Dibenzyl Ketone: Determination of the Spin Multiplicity of the Precursor.

ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.

ChemInform Abstract: Coupling of Anthrone by Mercury(II) Salts.

Its use as a phenol coupling reagent, however, has not been attempted much . Recently we have reported the coupling of 2,7-dihydroxynaphthalene using mercuric oxide2. Another report appeared in the literature that utilized Hg (II) salts for phenol coupling reaction. The mercuration, however, is more common process occurring in this type of reactions leading to organomercurals4.5. All these facts prompted us to undertake the reaction of anthrone (1) with common Hg (II) salts such as HgCI2 and Hg(OAch under different conditions. The isolation of a host of naturally occurring phenolic bianthronyls6 of important physiological properties and their probable biogenesis through oxidative phenol coupling of the respective monomers created interest amongst us in studying the possible coupling of anthrone leading to bianthronyls using Hg (II) salts. Earlier literature says that mercuric halide would insert to acidic carbons readily, a base helps, and thermal activation would lead to dimerization. For instance, the substrate dibenzyl ketone would dimerize to 1,4-dioxo-2,3,5,6tetrapheny lcyclohexane 7 . Acidity wise, anthrone is also activated and therefore has the chance to dimerize readily. It is interest ing to note that 1, when ICfluxed for nearly 3 hr with Hg(OAc)2 either in glacial acetic acid or in ethanol, afforded a single isolable product establi shed as bianthronyl 2 with >70% yields. The same product in >60% yield could also be obtained

Supramolecular Photochemistry in β-Cyclodextrin Hosts: A TREPR, NMR, and CIDNP Investigation

A systematic investigation of the photochemistry and ensuing radical chemistry of three guest ketones encapsulated in randomly methylated beta-cyclodextrin (beta-CD) hosts is reported. Dibenzyl ketone (DBK), deoxybenzoin (DOB), and benzophenone (BP) triplet states are rapidly formed after photolysis at 308 nm. Time-resolved electron paramagnetic resonance (TREPR) spectroscopy, steady-state NMR spectroscopy, and time-resolved chemically induced nuclear polarization (TR-CIDNP) experiments were performed on the ketone/CD complexes and on the ketones in free solution for comparison. The major reactivity pathways available from these excited states are either Norrish I alpha-cleavage or H-atom abstraction from the interior of the CD capsule or the solvent. The DOB triplet state undergoes both reactions, whereas the DBK triplet shows exclusively alpha-cleavage and the BP triplet shows exclusively H-atom abstraction. Radical pairs are observed in beta-CDs by TREPR, consisting of either DOB or BP ketyl radicals with sugar radicals from the CD interior. The TREPR spectra acquired in CDs are substantially broadened due to strong spin exchange. The electron spin polarization mechanism is mostly due to S-T(0) radical pair mechanism (RPM) in solution but changes to S-T(-) RPM in the CDs due to the large exchange interaction. The TR-CIDNP results confirm the reactivity patterns of all three ketones, and DOB shows strong nuclear spin polarization from a novel rearrangement product resulting from the alpha-cleavage reaction.

Electronic effects in the cyclocondensation of benzil

Electronic effects are important directing forces in the course of chemical reactions. Small differences in these effects can bring about considerable changes in the results of very similar reactions. Thus, although the ambident nucleophiles urea, ophenylenediamine and dibenzyl ketone are expected to take comparable double condensation pathway in their respective reaction with benzil, urea reacts differently by causing benzil-to-benzilic acid type rearrangement. This is attributed to the reduced availability of the lone pair of electrons on nitrogen in urea that is needed for assisting the dehydration of the intermediate.