Benzoin Isopropyl Ether Research Articles

Synergy of Oxygen Vacancies and Acid Sites on N-Doped WO3 Nanobelts for Efficient C–C Coupling Synthesis of Benzoin Isopropyl Ether

The surface property of a photocatalyst, including surface acid sites and oxygen vacancies, plays a pivotal role in photocatalytic organic synthesis reactions. Benzoin isopropyl ether (BIE) is usually produced via polycondensation of benzaldehyde and catalyzed with highly toxic cyanide. Here, we report a green photocatalytic approach for the selective synthesis of BIE over WO3 driven by a green-light-emitting diode. The improved photocatalytic activity can be attributed to the synergy of oxygen vacancies (VOs) and acid sites over N-doped WO3 nanobelts. The results revealed that reactant molecules were predominantly adsorbed and activated on surface oxygen vacancies (VOSs) and the Brønsted acid promoted the etherification reaction; the introduction of VOs and nitrogen altered the band structure and electronic properties, resulting in improved photocatalytic activity. Our work provides an efficient approach to the selective photocatalytic synthesis of organics over photocatalysts with finely tuned surface properties and band structures via defect and doping engineering.

Using NMR Spectroscopy and Chemical Synthesis to Establish Diastereoselectivity of NaBH4 and Meerwein–Ponndorf–Verley (MPV) Reduction of (±)-Benzoin Isopropyl Ether: A Collaborative Discovery-Based Laboratory Experiment

A discovery-based undergraduate organic chemistry lab experiment has been developed in which students establish the diastereoselectivity of hydride reduction of the α-chiral ketone (±)-benzoin isop...

A new way to synthesize benzoin isopropyl ether on Cu-Fe-hydrotalcite

An efficient synthesis of benzoin isopropyl ether with benzaldehyde and propanol in the presence of heterogeneous recyclable Cu-Fe-hydrotalcite catalyst has been explored. Cu-Fe-hydrotalcite was firstly successfully synthesized over Jahn-Teller effect of Cu 2+. The catalytic test result showed that Cu-Fe-hydrotalcite could be used as a good catalyst in the synthesis of benzoin isopropyl ether. The highest conversion of benzaldehyde was 59.7% and the selectivity of benzoin isopropyl ether was nearly 100%. By this new method, not only was the cyanide poisoning avoided, but also the synthesis of benzoin isopropyl ether could be completed in one step instead of traditional two steps with both condensation and etherification.

Xylitol Production from Rice Straw Hemicellulose Hydrolyzate by Polyacrylic Hydrogel Thin Films with Immobilized Candida subtropicalis WF79

Xylose from rice straw hemicellulose hydrolysate was fermented for xylitol production using Candida subtropicalis WF79 cells immobilized in polyacrylic hydrogel thin films of 200 mum thickness. Cell immobilization was conducted by first suspending the yeast cells in a mixture of 2-hydroxyethyl methacrylate (HEMA, hydrophilic monomer), polyethylene glycol diacrylate (PEG-DA, crosslinking agent), and benzoin isopropyl ether (photoinitiator). The mixture was then allowed to form polyacrylic hydrogel thin films, between two pieces of glass sheets, by UV-initiated photopolymerization. The hemicellulose of rice straw was hydrolyzed using dilute sulfuric acid at 126 degrees C. The hydrolysate was neutralized with calcium hydroxide. After separating the solid residues and calcium sulfate precipitates by filtration, the hydrolysate was treated with charcoal to partially remove potential inhibitory substances, followed by vacuum concentration to obtain solutions of desired xylose concentrations for yeast fermentation. The thin films with immobilized yeast cells were submerged in the xylose solution from rice straw hydrolysate for fermentation in an Erlenmeyer flask. The maximum yield was 0.73 g of xylitol per gram of xylose consumed. In the 52.5-day long durability test, after 40 d of repeated batchwise operation, the fermentation activities of the cell immobilized in thin films began to decline to a yield of 0.57 g/g at the end.

The Sensitization on Photopolymerization of Some Aromatic Tertiary Amines.

The influence of aromatic tertiary amine (ATA) on the rate of photopolymerization (Rp) was studied in the MMA/BIP (benzoin isopropyl ether) system to improve the photoinitiation activity and anti-oxygen power of the benzoin alkyl ether initiators by using an auto-expander.

Radical Polymerization of New Functional Monomers: Mono- and Di-methacryloyl Isocyanate Containing Bisphenol-S and its Derivatives

New functional monomers mono- and di-methacryloyl isocyanate containing bisphenol-S were prepared on reaction of methacryloyl isocyanate (MAI) with bisphenol-S (BPS) and its derivatives at low temperature. The monomers thus obtained were characterized with elemental analysis, infrared, ultraviolet, 1H and 13C-NMR (nuclear magnetic resonance) spectra. Radical polymerization of mono- and di-methacryloyl isocyanate containing bisphenol-S and its derivatives was studied in terms of the rate of polymerization, solvent effect, thermal properties and kinetic measurements of photocrosslinking. Polar solvents such as dimethyl sulfoxide and dimethylacetamide (DMAc) were found to slow the polymerization. Functional polymers containing the vinyl group of MAI were successfully modified and photocrosslinked on irradiation in the presence of benzoin isopropyl ether. The photocrosslinking process follows second-order kinetics.

Radical polymerization of new functional monomers: Mono‐ and dimethacryloyl isocyanate containing bisphenol‐A and its derivatives

New functional monomers mono-and dimethacryloyl isocyanate containing bisphenol-A were prepared on reaction of methacryloyl isocyanate (MAI) with bisphenol-A (BPA) and its derivatives at low temperature. The monomers thus obtained were characterized with IR, UV, and 1H- and 13C-NMR spectra. Radical polymerization of mono-and dimethacryloyl isocyanate containing bisphenol-A and its derivatives was studied in terms of the rate of polymerization, solvent effect, copolymerization, thermal properties, and kinetic measurements of photocrosslinking. Polar solvents such as DMSO and NMP were found to slow the polymerization. Copolymerization of BPA-MAI (M1) with MMA (M2) in DMF was studied at 90°C. The monomer reactivity ratio was calculated to be r1 = 0.17 and r2 = 1.34 according to the method of Fineman–Ross. Functional polymers containing the allyl group were successfully modified and photocrosslinked on irradiation in the presence of benzoin isopropyl ether. The photocrosslinking process follows second-order kinetics. © 1996 John Wiley & Sons, Inc.

Radical polymerization of new functional monomers: Mono- and dimethacryloyl isocyanate containing bisphenol-A and its derivatives

New functional monomers mono-and dimethacryloyl isocyanate containing bisphenol-A were prepared on reaction of methacryloyl isocyanate (MAI) with bisphenol-A (BPA) and its derivatives at low temperature. The monomers thus obtained were characterized with IR, UV, and 1H- and 13C-NMR spectra. Radical polymerization of mono-and dimethacryloyl isocyanate containing bisphenol-A and its derivatives was studied in terms of the rate of polymerization, solvent effect, copolymerization, thermal properties, and kinetic measurements of photocrosslinking. Polar solvents such as DMSO and NMP were found to slow the polymerization. Copolymerization of BPA-MAI (M1) with MMA (M2) in DMF was studied at 90°C. The monomer reactivity ratio was calculated to be r1 = 0.17 and r2 = 1.34 according to the method of Fineman–Ross. Functional polymers containing the allyl group were successfully modified and photocrosslinked on irradiation in the presence of benzoin isopropyl ether. The photocrosslinking process follows second-order kinetics. © 1996 John Wiley & Sons, Inc.

Radical polymerization of new functional monomers: mono- and dimethacryloyl isocyanate containing bisphenol-AF and its derivatives

New functional monomers mono- and dimethacryloyl isocyanate containing bisphenol-AF were prepared on reaction of methacryloyl isocyanate (MAI) with bisphenol-AF (BPAF) and its derivatives at low temperature. The new monomers thus obtained were characterized with IR, UV, 1H- and 13C-NMR spectra. Radical polymerization of mono- and dimethacryloyl isocyanate containing bisphenol-AF and its derivatives was studied in terms of the rate of polymerization, solvent effect, copolymerization, thermal properties and kinetic measurements of photocrosslinking. Polar solvents such as DMSO and NMP were found to slow the polymerization. Copolymerization of BPAF-MAI (M 2) with styrene (M 2) in DMF was studied at 90°C. The monomer reactivity ratio were calculated to be r 1 = 0.77 ± 0.08 and r 2 = 2.50 ± 0.22 according to the method of Fineman-Ross. Functional polymers containing the allyl group were successfully modified and photocrosslinked on irradiation in the presence of benzoin isopropyl ether. The photocrosslinking process follows second order kinetics.

Radical polymerization of mono‐ and di‐methacrylic esters containing bisphenol‐S

AbstractRadical polymerizations of mono‐ and di‐methacrylic esters containing bisphenol‐S (BPS‐M and BPS‐DM) were studied in terms of polymerization rate, solvent effect, copolymerization and kinetic measurements of photocrosslinking. The solvents were found to affect significantly the polymerization rate. Polar solvents such as DMSO and acetonitrile were found to slow down the polymerization rate. Copolymerization of BPS‐M(M1) with MMA(M2) was studied in acetone at 60°C. The monomer reactivity ratios were calculated to be r1 = 3.72 ± 0.01 and r2 = 0.80 ± 0.01 by the Fineman‐Ross method. The high reactivity of BPS‐M observed in this copolymerization system may be due to the “matrix effect”. Functional polymers containing methacrylate side‐groups were successfully modified and photocrosslinked by irradiation in the presence of benzoin isopropyl ether. The photocrosslinking process is found to be of second order kinetics.

Photopolymerization of methyl methacrylate using benzoin isopropyl ether as photoinitiator: Effect of thiophenol compounds

AbstractEffects of a series of thiophenols RArSH with substituting groups R in the para‐position and 2‐mercaptobenzoic acid on the kinetics of polymerization of methyl methacrylate (MMA) photoinitiated by benzoin isopropyl ether (BIPE) were investigated using an autorecording dilatometer. Thiophenols were found to have a dual effect on polymerization: reducing induction time and accelerating rate of polymerization. A mechanism was proposed suggesting that this increased rate of polymerization and reduced induction time with addition of a thiophenol is due to the fact that, instead of consuming radicals, the dissolved oxygen in the MMA/BIPE system can be converted into active radicals through effective photooxidation of the thiophenol. Although the maximum increase in rate of polymerization is of a minor difference between various thiophenol compounds, reduction in induction time is strongly dependent on the nature of substituting groups in the following order: CH3 > CH(CH3)2 > OCH3 or Cl > H. 2‐Mercaptobenzoic acid, on the other hand, increases induction time and decreases rate of polymerization. © 1993 John Wiley & Sons, Inc.

Photochemical synthesis of nitroxyl free radicals in the presence of vinyl monomers

AbstractThe photochemical formation of an inhibitor in the presence of monomers and a photoinitiator offers the possibility of producing positive two‐step photoresists. As inhibitor precursor sterically hindred amines have been used in the presence of air oxygen and Rose Bengal as oxidation photosensitizer. On irradiation with visible light (546 nm). stable nitroxyle radicals are formed, which act as strong inhibitors of free radical polymerization. Hexanediol diacrylate and 2‐acryloxy‐2′‐propionyl oxydiethylether were used as monomers. The photoinitiator required for the second step polymerization is benzoin isopropyl ether, which photolyzes on irradiation at 340 n,. The quantum yield of nitroxyl radical formation has been determined in solution and in polymeric films. Polymerization inhibition experiments were carried out with methyl methacrylate in solution and with neat monomers. Though the quantum yield ΦNO° is low, especially in the last case, the experiments confirm the possibilities of this two‐step procedure.

Light-induced polymer and polymerization reactions—42. A kinetic study of cationic photopolymerization with (benzoin derivative)/(onium salt) systems

Epoxides can be polymerized by cations produced by electron-transfer from photochemically generated nucleophilic radicals to onium salts. Effects of various parameters such as absorbed light intensity ( I abs), onium salt concentration ([On +]), and type of radical source on the rate of polymerization have been measured and appropriate kinetic expressions explaining these dependencies have been derived. For these studies 2,3-epoxypropyl phenyl ether (phenyl glycidyl ether) was used as monofunctional epoxide. The radical sources were 2,3-dimethoxy 2-phenyl acetophenone (benzil dimethyl ketal) (BDMK), benzoin isopropyl ether (BIPE) and α-phenyl benzoin (α-PhB). Diphenyliodonium hexafluorophosphate was the electron acceptor. The quantum yields ( φ P ) of the polymerization, calculated from the polymerization rate R p, follow the order BDMK ⪢ BIPE > α-PhB. Both iodonium salt concentration and light intensity are related reciprocally to monomer conversion. The k p/ k t values calculated from the kinetic expressions lie in the range 22–54 l mol −1.

Study of photopolymers. XXX. Syntheses of new di(meth) acrylate oligomers by addition reactions of epoxy compounds with active esters

AbstractSome dimethacrylate oligomers were synthesized by new addition reactions of 2,2‐(4‐hydroxyphenyl)propane diglycidyl ether (BPGE) or glycidyl methacrylate (GMA) with phenyl methacrylates such as phenyl methacrylate (PMA), 4‐nitrophenyl methacrylate (NPMA), 2,4‐dichlorophenyl methacrylate (DCPMA), 4‐methoxyphenyl methacrylate (MPMA), and (4‐cinnamoyloxy)phenyl methacrylate (CIPMA) using tetrabutylammonium bromide as a catalyst at 120°C. The other new dimethacrylate or diacrylate oligomers were also prepared by the addition reactions of GMA or glycidyl acrylate with active esters such as di(S‐phenyl)thioisophthalate (PTIP), di(4‐nitrophenyl)isophthalate (NPIP), di(4‐nitrophenyl)adipate (NPAD), and di(4‐nitrophenyl)sebacate (NPSB) under similar reaction conditions. Furthermore, the rates of photochemical reaction of the obtained dimethacrylate oligomers were measured with 3 mol % of various photosensitizers such as benzoin iso‐propyl ether (BIPE), 2‐ethylanthraquinone (EAQ), and benzophenone (BP). The rate of photochemical reaction of BPGE‐DCPMA oligomer was higher than those of BPGE‐PMA, BPGE‐NPMA, and BPGE‐MPMA oligomers using BIPE as a photosensitizer. However, the photochemical reactivity of the unsensitized BPGE‐CIPMA was almost the same as that of the sensitized BPGE‐DCPMA. On the other hand, when EAQ was used as a photosensitizer, GMA‐PTIP oligomer showed much higher reactivity than GMA‐NPAD, GMA‐NPSB, and GMA‐NPIP oligomers. Also it was shown that the activity of EAQ as a sensitizer was higher than BIPE and BP in the photochemical reaction of BPGE‐DCPMA oligomer.

Ultraviolet-curing blends for coating of optical fibres

An ultraviolet-curable polymeric blend was developed to serve as a coating for optical fibres. The composition of the system was 55.6 wt% urethane acrylate, 44.4 wt% epoxyacrylate, 1.5 wt% benzoin isopropyl ether and 25 wt% 1,3-butanediol diacrylate. Three different silane coupling agents were tested to improve the polymer-glass adhesion. The optical fibres were drawn at 0.45 m sec−1 using a CO2 laser; the ultraviolet curing blend was applied and cured with a xenon flash lamp. Ageing studied in water and in humid environments performed on these coated fibres showed that there was an increase in their strength compared to the silicone-coated fibres. It was possible to triple the fibre's drawing velocity without affecting the percentage conversion of the resin and the mechanical and optical properties of the fibre.

Lichtinitiierte polymer‐ und polymerisationsreaktionen, 26. Elektrophile ringöffnungsreaktionen zwischen glycidylethern und ketonen oder aldehyden initiiert durch photoinitiatorsysteme

AbstractBy the irradiation of benzoin derivatives in the presence of arene diazonium salts or aryl iodonium salts cationic species are formed, which initiate ring‐opening reactions of 2,3‐epoxy‐propyl (glycidyl) ethers in the presence of ketones or aldehydes. 1,3‐Dioxolane formation dominates over homopolyaddition reactions of glycidyl ethers. This method forms dioxolane in satisfactory preparative yields. The quantum yields of disappearance of phenyl glycidyl ether in acetone (ΦPGE) were measured in dependence of some system parameters. By the photolysis of benzil dimethyl ketal more catalytic species are produced as in the case of benzoin isopropyl ether or α‐phenylbenzoin. The ΦPGE values for diazonium salts are higher than for iodonium salts, with triphenylsulfonium salts the reaction failed. With the anions of iodonium salts the following sequence for ΦPGE is observed: SbF6− > PF6− ≫ SbCl6− = BF4− = 0. Because the key step of the catalyst formation is an electron transfer reaction between radicals produced by the photolysis and the onium ions, the concentration of the salts influences ΦPGE. Phenyl glycidyl ether reacts more rapidly than 2,2‐bis(4‐hydroxyphenyl)trimethylene diglycidyl ether and isobutyl glycidyl ether.

Mechanism of the photochemical reduction of CCl bond in fluorine compounds

The photochemically initiated substitution of a halogen for hydrogen atom represents a preparative reaction, that can be expressed by the general scheme: ▪ The reaction is characterized by a high selectivity in polyhalogeno compounds as demonstrate examples of successfully performed preparations: CF 3CBr 2Cl → CF 3CHBrCl, CCl 2FCClF 2 → CHClFCClF 2, CF 3CClFCCl 3 → CF 3CClFCHCl 2. A marked directive effect on the regioselectivity of the reduction is exhibited by the ester group in fluorinated propanoates: CFXYCClZCOOR → CFXYCHZCOOR (X,Y = F,Cl). The quantum yields of this reduction in 2-propanol are as high as several hundreds of units, which is indicative of the chain mechanism. The photo-reduction is auto-sensitized by the resulting acetone. The kinetic model of the reduction indicates, under a definite ratio of the terminal reaction rates, a rate limit independent of the concentration of the starting substance. The kinetic model of the reduction initiated by α-phenyl benzoin and benzoin isopropyl ether was verified also using the Stern-Volmer dependence of a total quantum yield of HCl.

Photoinitiated polymerization of 1-vinylimidazole

The photoinitiated polymerization of 1-vinylimidazole (VI) does not follow the classical kinetic scheme for free radical polymerization. Kinetic results for VI suggest a degradative addition reaction between the macroradical and the monomer to produce a relatively stable, unreactive radical, which does not reinitiate polymerization, is low, 1.5 kcal/mol. Among the 3 photoinitiators used, the highest quantum efficiency was demonstrated by 2,2'-diethoxyacetophenone followed by bezoin methyl ether and benzoin isopropyl ether. Under the experimental conditions used, the polymerization of VI does not proceed to complete conversion, and the phenomenon of dead-end polymerization is observed.

Photocrosslinking of unsaturated polymethacrylic esters

Copolymers of n.butyl methacrylate and glycidyl methacrylate (GMA) containing 11, 22, 40 and 51% GMA units were reacted quantitatively with methacrylic acid, producing copolymers with methacrylate side-groups. These copolymers were submitted to photocrosslinking by irradiation at 350 nm in the presence of benzoin isopropyl ether as photoinitiator in the solid state below and above the glass transition temperature of the copolymers. The rate of crosslinking was followed by: 1. (1) Infrared spectrometry by measuring the relative decrease of absorbance of the double bond CC (1640 cm −1). 2. (2) Microcalorimetry on the basis of the initial exothermic peak. 3. (3) By gravimetry by determining the increase of insoluble fraction with time of irradiation. The influence of temperature on the rate of crosslinking was examined above T g . The apparent activation energy of crosslinking varies from 7·5 to 15 kcal mol −1; it is a function of the film thickness because of the influence of segmental motion and viscous flow effects. Increasing the total unsaturation by addition of polyfunctional acrylic ester causes a strong increase in the rate of crosslinking.

Flash photolysis investigation on primary processes of the sensitized polymerization of vinylmonomers. III. Photoreactions of benzoin compounds and stationary polymerization experiments

AbstractBenzoin (B), benzoinacetate (BA), benzoinmethylether (BME) and benzoinisopropylether (BIPE) were irradiated at room temperature in benzene solution in the presence of styrene (St), methyl methacrylate (MMA), vinylacetate (VAc) or acrylonitrile (AN). Flash photolysis experiments at λ=347 nm yielded (a) rate constants kq (in 1 mol‐1s‐1) of the reaction between excited sensitizers and monomers: 8·109 (B/St), 5·108 (B/MMA), 5·109 (BA/St), 8·108 (BA/MMA); (b) rate constants KR.+M (in 1mol‐1 s‐1) of the reaction between sensitizer radicals and monomers: about 1.5·105 (BME/St, BME/VAc, BA/VAc, B/VAc), 9· 104 (BME/MMA), 2·104 (BME/AN). The reaction R·+M caused in certain cases (B/St, B/VAc, BME/St) the formation of an additional optical absorption after the flash.Stationary irradiations at λ>320 nm of monomer solutions (5mol/1) showed that BA is least effective. Rates of polymerization increased in the series BA<B<BIPE<BME. For the systems containing St or MMA it was found that ϕi=i+0.6αR (ϕi=quantum yield for the initiation of kinetic chains, αR =fraction of triplets converted to radicals). The fraction of radicals starting kinetic chains is ca. 0.3 in these cases.