Acylation Of Ferrocene Research Articles

Synthesis of long straight‐chain alkane substituted ferrocene with ultra‐robust oil solubility as multifunctional organometallic additive

Tailoring of organometallics structure toward desirable properties continues to be both fascinating and challenging in the field of materials science. Herein, a novel ferrocene derivative with long straight‐chain alkane mono‐substituent is synthesized and used as multifunctional organometallic additive in the base oil. This ferrocene‐based organometallic compound (MFc) is synthesized via the Friedel‐Crafts acylation of ferrocene with myristyl chloride, followed by reduction with sodium borohydride. The chemical structure, crystallizability, surface morphology, and the thermal properties of the as‐synthesized compound are systematically characterized. As the iron‐containing standard substance, the MFc was preferable dissolve in lubricating oil with the iron element content as high as 2*105 ppm. Resultantly, the MFc/oil solutions exhibited excellent stability even after high‐speed centrifugal treatment, long‐term storage up to 3 months, and ultra‐low temperature treatment at −40°C for 24 h. Moreover, the MFc as a functional lubricant additive could reduce the average wear scar diameter, wear volume, and coefficient of friction with 40%, 73%, and 18%, respectively, as compared to the corresponding pure base oil. This synthetic strategy provides a novel perspective for the design of functional organometallics, and the as‐synthesized novel ferrocene derivative may find a wide range of advanced potential applications in analytical chemistry, tribology, and interfacial science.

Synthesis, Crystal Structure, and Electrochemistry of Mono- and Bis-Homoannular Ferrocene Derivatives

Two ferrocene derivatives, namely, 1,2-(tetramethylene)-ferrocene and 1,2,1′,2′-bis(tetramethylene)-ferrocene, were synthesized in a four-step reaction sequence starting from ferrocene. Friedel–Crafts acylation of ferrocene using succinic anhydride gave mono- or bis(3-carboxypropinoyl)-ferrocene depending on the stoichiometry of succinic anhydride. The reduction of the keto groups to methylene followed by ring-closing using trifluoroacetic anhydride gave 1,2-(α-ketotetramethylene)-ferrocene or 1,2,1′,2′-bis(α-ketotetramethylene)-ferrocene. The diastereomeric mixture of the latter diketones was separated using column chromatography, characterized via single-crystal X-ray analysis, and assigned its stereochemistry. Reduction of the keto groups to methylene under Clemmensen conditions gave homoannular mono- or bis(tetramethylene)-ferrocene derivatives. The molecular structure of 1,2-(tetramethylene)-ferrocene revealed that the ipso carbon atoms of the cyclopentadienyl group are 0.023(3) Å farther away from Fe(II) compared to the remaining three carbon atoms. Both complexes exhibit lower half-wave oxidation potentials than ferrocene, possibly due to the electron-releasing effects of the tetramethylene bridges.

Conductive Mediators in Oxidation Based on Ferrocene Functionalized Phosphonium Ionic Liquids

Herein, the synthesis of ferrocene-containing salts is presented. Acylation of ferrocene (Fc) according to the Friedel-Crafts method led to ω-bromoacyl ferrocenes. The ω-bromoacyl ferrocenes were subsequently introduced to quaternization reaction with tri-tert-butyl phosphine, which resulted in phosphonium salts. Obtained phosphonium salts were characterized by physical methods. The electrochemical properties of phosphonium salts were studied by cyclic voltammetry (CV). It was found that the replacement of n-butyl fragments at the phosphorus atom by tert-butyl leads to a more anodic potential shift. In contrast to isolobal structures Fc-C(O)(CH2)nP+(n-Bu)3X- and Fc-(CH2)n+1P+(n-Bu)3X-, the CV curves of Fc-C(O)(CH2)nP+(t-Bu)3X- and Fc-(CH2)n+1P+(t-Bu)3X- did not show a large discrepancy between forward and reverse currents. The transformation of the C=O groups to CH2 fragments had a significant effect on the electrochemical properties of ferrocene salts, the oxidation potential of which is close to that of pure ferrocene.

Synthesis of 5-(dimethylsilyl)pentylalkylferrocene-grafted HTPB (alkylFc-HTPB) via platinum-catalyzed hydrosilylation

In this work, at first alkylferrocene derivatives were synthesized according to procedure described in the literature. (5-Chloropentanoyl)ferrocene derivatives were prepared by Friedel–Crafts acylation of ferrocene and alkylferrocene derivatives with 5-chloropentanoyl chloride in dichloromethane, and AlCl3 was used as catalyst. The corresponding 5-chloropentylferrocene derivatives were synthesized from reduction of these products by NaBH4 in diglyme at 0 °C. Finally (5-alkylferrocenylpentyl)dimethylsilane was synthesized from reaction of 5-chloropentylferrocene derivatives with magnesium in THF and reaction of corresponding Grignard reagents with chlorodimethylsilane in 82–87% yields. 1H and 13C NMR, FT-IR spectroscopy supported the predicted structure of the product. Nine samples of alkylferrocene-grafted hydroxyl-terminated polybutadiene (alkylFc-HTPB) derivatives, containing different percent of iron, were synthesized by hydrosilylation reaction of [5-(alkylferrocenyl)pentyl]dimethylsilane with hydroxy-terminated polybutadiene (HTPB), in the presence of catalytic amount of the hexachloroplatinic acid (Speier’s catalyst). FT-IR spectroscopy was utilized to follow the progress of the reaction, by monitoring the loss of the Si–H absorption at 2110 cm−1, and the reaction was completed in 24 h. Some properties of resulting prepolymer like viscosity, glass transition temperature and iron percentage as important parameters in production of composite propellants were investigated. For example, the viscosity increased with increasing iron content because of the greater extent of ferrocene grafting in the polymer.

Synthesis of new ferrocene derivatives with a 4,5-dichloroisothiazole fragment

Conjugates of ferrocene and 4,5-dichloroisothiazole were synthesized, where the ferrocene and isothiazole moieties are linked through various structural fragments. The acylation of ferrocene with 4,5- dichloroisothiazole-3-carbonyl chloride gave (4,5-dichloroisothiazol-3-yl) ferrocenyl ketone; the acylation of aminomethylferrocene furnished the corresponding amide. The esterification of ferrocene-1,1′-dicarboxylic acid with 4,5-dichloroisothiazol-3-yl-methanol resulted in the formation of the corresponding ester. The condensation of 1,1′-diacetylferrocene with 4,5-dichloroisothiazole-3-carbaldehyde afforded ferrocenophane containing 4,5-dichloroisothiazole moieties.

Ferrocene-Biotin Conjugates: Synthesis, Structure, Cytotoxic Activity and Interaction with Avidin.

Friedel-Crafts acylation of ferrocene with d-biotin, d-homobiotin and d-desthiobiotin gave ferrocenyl ketones. These compounds were diastereoselectively reduced to the corresponding alcohols using (R)- and (S)-Me-CBS-oxazaborolidine-borane complexes as reducing agents. The alcohols were further transformed into azido and finally to amino derivatives with retention of configuration, as confirmed by X-ray crystallography. Ferrocenylbiotin alcohols smoothly underwent dehydration to (E)-alkenes as the major isomers by heating in diluted acetic acid. The synthesized compounds retained high affinity for avidin. They also exhibited high cytotoxicity toward cancer cells expressing various levels of sodium-dependent multivitamin transporter (SMVT) in the absence of biotin in the medium, whereas the presence of free biotin decreased their antiproliferative activity. This revealed that these biotin-ferrocene conjugates might be used as biologically active agents against cancer cells, although there was no clear relationship between their cytotoxicity and cellular SMVT level.

Synthesis and Characterization of New Ferrocene‐Containing Ionic Liquids

AbstractA series of several new families of ferrocene‐containing imidazolium salts were synthesized by etherification of ferrocene methanol, acylation of ferrocene, and amide coupling of ferrocene carboxylic acid. The etherification was achieved by an acid‐catalyzed procedure and very good yields of between 86–93 % were obtained. Next to the nature of the linkage itself, the lengths of the alkyl chains linking the ferrocenyl moiety and the imidazolium group and the nature of the counterions were also varied. Interestingly, a γ‐effect can be observed for the ether compounds but this effect was only visible in 13C NMR spectroscopy. These new redox‐active ionic liquids were fully characterized by FTIR, 1H, 19F, and 13C NMR spectroscopy, and by MS, HRMS and elemental analysis.

Ferrocene–Biotin Conjugates Targeting Cancer Cells: Synthesis, Interaction with Avidin, Cytotoxic Properties and the Crystal Structure of the Complex of Avidin with a Biotin–Linker–Ferrocene Conjugate

Friedel–Crafts acylation of ferrocene with a biotin-derived carboxylic acid having 6-aminohexanoyl linkers attached to the biotin carboxylic group and with desthiobiotin afforded the corresponding ferrocene–biotin bioconjugates. These compounds as well as biotinyl ferrocenyl ketone exhibit high affinity for avidin. Their cytotoxicity against cancer cell lines having various levels of biotin receptors (SMVT) was measured and revealed that lines displaying high levels of SMVT (SW620) were the most susceptible. This suggests that biotin serves as a biological vector delivering cytotoxic ferrocenyl moieties to cancer cells. The crystal structure of the complex of avidin with a conjugate having two linker units between biotin and ferrocene was determined and revealed stabilization of several different conformations of the ligand within the protein binding pocket.

The timing of an experiment in the laboratory program is crucial for the student laboratory experience: acylation of ferrocene as a case study

An assessment of the acylation of ferrocene laboratory exercise across three successive years resulted in a significant fluctuation in student perception of the experiment. This perception was measured by collecting student responses to an instrument immediately after the experiment, which includes Likert and open-ended responses from the student. Students in all three years identified technical benefits from the experiment. In Years 1 and 3, students also recognised the benefits of improving their conceptual understanding of organic chemistry. However, in Year 2, where background knowledge became a critical and limiting factor, all perception of conceptual understanding as an experiment objective was lost, and only recognition of technical development remained. Analysis of these data also indicated that students who have enough time to complete the experiment also perceive a measure of responsibility for their own learning, whereas time-poor students have an over-reliance on the laboratory notes and demonstrators. Addressing concepts such as these may be the triggers required for time-poor experiments to garner a positive student experience and maximise both the conceptual and technical benefits of the experiment.

ChemInform Abstract: Rare Earth Solid Superacid Catalyzed Friedel—Crafts Acylation of Ferrocene.

Abstract The Friedel–Crafts acylation of ferrocene catalyzed by a new type of catalyst of rare-earth solid superacid sulfated zirconia SZR3+ was developed. Comparison of catalytic activities between different solid acid catalysts is presented. The catalyst, sulfated zirconia ytterbium SZNYb3+, showed interesting catalytic properties for preparation of acylferrocenes. Furthermore, the catalyst could be regenerated and reused in succession after simple filtration.

Rare Earth Solid Superacid Catalyzed Friedel–Crafts Acylation of Ferrocene

The Friedel–Crafts acylation of ferrocene catalyzed by a new type of catalyst of rare-earth solid superacid sulfated zirconia SZR3+ was developed. Comparison of catalytic activities between different solid acid catalysts is presented. The catalyst, sulfated zirconia ytterbium SZNYb3+, showed interesting catalytic properties for preparation of acylferrocenes. Furthermore, the catalyst could be regenerated and reused in succession after simple filtration.

Active esters as acylating reagents in the Friedel–Crafts reaction: trifluoromethanesulfonic acid catalyzed acylation of ferrocene and pyrene

The Friedel–Crafts acylation of electron-rich arenes (ferrocene and pyrene) with N-hydroxysuccinimidyl, 2,3,5,6-tetrafluorophenyl and phenyl esters of benzoic and p-methoxybenzoic acid, activated by superacidic trifluoromethanesulfonic acid is reported. The reactive acylating intermediate in this system is presumably an acyl triflate or its protonated form.

Acylation of Ferrocene with Adamantoyl Chloride and Cinnamoyl Chloride

Liquid phase acylation of ferrocene with adamantoyl and cinnamoyl chloride was studied over different structural types of zeolites. The effect of the zeolite structure and acidity, and the influence of the reaction conditions on the ferrocene conversion and selectivity was investigated. The highest ferrocene conversions were achieved over zeolite Beta with Si/Al ratio 12.5 (cinnamoyl chloride 63.5%, adamantoyl chloride 45.9%). It was observed that with decreasing concentration of active sites in zeolite Beta the ferrocene conversion decreases. In addition, it was found that there is an optimum molar ratio of ferrocene to acylating agent, the ferrocene conversion increased with increasing temperature and amount of catalyst. The most important finding is that acylation of ferrocene with adamantoyl and cinnamoyl chloride leads exclusively to monoacylated products, most probably due to a deactivation of the cyclopentadiene rings after the attachment of the first acyl group.

Synthesis, spectral characterization and electrochemical properties of (2-alkylthiobenzoyl)ferrocenes. Crystal structures of 2-methylthio, 2-ethylthio and 2-isopropylthio derivatives

The one-pot synthesis of seven new (2-alkylthiobenzoyl)ferrocenes has been achieved by Friedel–Crafts acylation of ferrocene with acid chlorides generated in situ from the corresponding carboxylic acids and phosphorous trichloride. The obtained compounds were characterized by spectroscopic data (UV, IR, 1H and 13C NMR), whereas their electrochemical properties have been investigated by cyclic voltammetry. The single-crystal X-ray structure determinations for three of them are also reported. Each of the three derivatives exhibits the intramolecular C–H…O interaction which involves the donor from the cyclopentadienyl (Cp) ring and the carbonyl oxygen as acceptor. This interaction favors the coplanar arrangement of the two moieties. The angles between the vectors coinciding the C–O bonds and the corresponding Cp planes are all below 6.4°. Conventional hydrogen bonds do not exist in any of the three crystal structures but some weak intermolecular interactions of the C–H…O, C–H…S and C–H…π types have been found and analyzed in detail. Different geometrical parameters for these crystal structures as well as for 22 similar ones extracted from Cambridge Structural Database (CSD) have been compared and analyzed.

Thermodynamic functions of buthylderivatives of ferrocene

The heat capacity of isobuthanoylferrocene, C5H5FeC5H4-COCH(CH3)2, was measured by low-temperature adiabatic calorimetry. The purity, temperature, and enthalpy of fusion were obtained. The ideal gas thermodynamic functions were derived at T = 298.15 K. The purity and thermodynamic functions of fusion of isobuthylferrocene, C5H5FeC5H4-CH2CH(CH3)2, were obtained by differential scanning calorimetry. The sample was synthesized by the reduction of isobuthanoylferrocene obtained by the direct acylation of ferrocene.

Friedel–Crafts acylation of ferrocene with alkynoic acids

Abstract Ferrocene reacts with alkynoic acids (conjugated or nonconjugated terminal), trifluoroacetic anhydride and triflic acid (or boron trifluoride etherate) to afford the corresponding ferrocenyl ynones in good yields. Only in the case of propynoic- and 3-butynoic acid complex, untreatable reaction mixtures were obtained. However, propynoilferrocene was obtained by desilylation of (trimethylsilyl)propynoilferrocene with KF/18-crown-6. Reaction with nonconjugated terminal alkynoic acids, carried out in the presence of a large excess of triflic acid (4 equiv.) results in formation of complex mixtures of products (in the reaction with 4-pentynoic acid enol triflate of ferrocenyl 1,4-diketone and 2-ferrocenyl-5-methylfuran were isolated). Ferrocenyl ynones obtained in this work can be used for synthesis of more complex ferrocenyl systems by “click” chemistry.

Acylations with Long-Chain Acid Anhydrides and Acyl Chlorides over Zeolite Beta

Acylation of ferrocene and toluene with linear, branched and aromatic anhydrides and chlorides of different chain length was investigated over zeolite Beta with Si/Al ratio 12.5. It was found that the conversion of ferrocene increased from acetic to butyric anhydride/chloride and then decreased with further increasing of chain length. The selectivity to 1-acylferrocene was in all cases 100%. In the case of toluene acylation, the conversions of acylating agent increased with the chain length of acylating agent up to hexanoic derivatives then the conversion of acylating agent was almost constant. The selectivity to p-isomer in toluene acylation increased with the chain length. The lowest conversions in both cases were achieved with benzoic anhydride and benzoyl chloride.

Synthesis of mono-and 1,1′-bis(3,4,4-trichlorobut-3-enoyl)-ferrocenes and 3,4,4-trichlorobut-3-enoylcymantrene

Friedel-Crafts acylation of ferrocene and cymantrene with 3,4,4-trichlorobut-3-enoyl chloride gave the corresponding trichloroallyl ferrocenyl and cymantrenyl ketones. The reaction with ferrocene involved either one or both cyclopentadienyl fragments, depending on the reactant ratio. The acylation of acetylferrocene with 3,4,4-trichlorobut-3-enoyl chloride afforded 1-acetyl-1′-(3,4,4-trichlorobut-3-enoyl)ferrocene.

Acylation of Ferrocene: A Greener Approach

The acylation of ferrocene is a common reaction used in organic laboratories to demonstrate Friedel–Crafts acylation and the purification of compounds using column chromatography. This article describes an acylation of ferrocene experiment that is more eco-friendly than the conventional acylation experiment. The traditional experiment was modified by replacing mineral acid with a polymeric acid catalyst and by using microwave heating instead of conventional heating.

Density Functional Study of Protonated Formylmetallocenes

Protonated formylmetallocenes [M(C5H5)(C5H4-CHOH)]+ (M = Fe, Ru) and their isomers have been studied at the BP86 and B3LYP levels of density functional theory. Oxygen-protonated isomers are the most stable forms in each case, with a plethora of ring- or metal-protonated species at least ca. 14 and 10 kcal/mol higher in energy for M = Fe and Ru, respectively. The computed rotational barriers around the C−C bond connecting the cyclopentadienyl and protonated formyl moieties, ca. 18 kcal/mol, are indicative of substantial conjugation between these moieties. Some of the ring- and iron-protonated species are models for possible intermediates in Friedel–Crafts acylation of ferrocene, and the computations provide further evidence that exo attack is clearly favored over endo attack of the electrophile in this reaction. The structures of the most stable mono- and diprotonated formylferrocenes are corroborated by the good agreement between GIAO-B3LYP-computed and experimental NMR chemical shifts.