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The synthesis of 1-methoxy-2-propanol (1-MP), which is expected as a safe alternative for toxic ethylene glycol ether, is highly demanded in chemical engineering. Herein, we report a series of task-specific anion-functionalized poly(ionic liquid)s (PILs) to trigger an effective catalysis in the 1-MP production through a reaction of propylene oxide (PO) and methanol. The acquired PIL catalysts, which are induced by phenolate anions, allow extraordinary PO conversion of 90.8 % and outstanding 1-MP yield and selectivity of 86.5 % and 95.3 % under very mild conditions. It also feasibly applies to the catalysis of a wide range of alcohols and PO to synthesize propylene glycol ethers (PGEs), and shows robust and facilitate reusability. Through a DFT calculation and in-situ 2D-IR survey, we reason that these significant performances are enabled by hydrogen-bonding interaction from the imidazole on the backbone for PO activation, and by the unique nucleophilicity of anions for the generation of activated methanol. [Display omitted] • P[BVim]PhO enables production of propylene glycol monomethyl ether under mild conditions. • P[BVim]PhO shows robust and facilitate reusability. • DFT calculation and in-situ 2D-IR survey confirm the catalytic mechanism. • Our PILs activate methanol and propylene oxide by nucleophilic anions and imidazole groups. [ABSTRACT FROM AUTHOR]

Abstract: Aging adults represent the fastest growing population segment in many countries. Physiological and metabolic changes in the aging process may alter how aging adults biologically respond to pollutants. In a controlled human toxicokinetic study (exposure chamber; 12m3), aging volunteers (n =10; >58 years) were exposed to propylene glycol monomethyl ether (PGME, CAS no. 107-98-2) at 50ppm for 6h. The dose-dependent renal excretion of oxidative metabolites, conjugated and free PGME could potentially be altered by age. Aims: (1) Compare PGME toxicokinetic profiles between aging and young volunteers (20–25 years) and gender; (2) test the predictive power of a compartmental toxicokinetic (TK) model developed for aging persons against urinary PGME concentrations found in this study. Methods: Urine samples were collected before, during, and after the exposure. Urinary PGME was quantified by capillary GC/FID. Results: Differences in urinary PGME profiles were not noted between genders but between age groups. Metabolic parameters had to be changed to fit the age adjusted TK model to the experimental results, implying a slower enzymatic pathway in the aging volunteers. For an appropriate exposure assessment, urinary total PGME should be quantified. Conclusion: Age is a factor that should be considered when biological limit values are developed. [Copyright &y& Elsevier]

Mg–Al hydrotalcites with different Mg/Al molar ratios were prepared and characterized by XRD, FT-IR, SEM and BET analyses. The calcined hydrotalcite with Mg/Al molar ratio of 4.0 (LDO Mg/Al 4.0) exhibited the highest catalytic activity in the synthesis of propylene glycol methyl ether (PM). The catalytic activity relating to the amount of the basic sites and crystallinity depended on the Mg/Al molar ratio. The optimal equilibrium of acid–base property and high crystallinity made the LDO Mg/Al 4.0 an excellent catalyst in the reaction. Etherification of propylene oxide (PO) with methanol over the LDO Mg/Al 4.0 was researched. The optimized reaction conditions were as follows: 140 °C, catalyst amount 0.9 wt%, methanol/PO molar ratio 4.0 and 6 h. The PO conversion and PM selectivity were 93.2 and 97.4%, respectively. Above all, almost all the PM was 1-methoxy-2-propanol, for no 2-methoxy-1-propanol was detected by GC analysis in the reaction products, and the catalyst could be reused for five times. The particles of the LDH Mg/Al 4.0 showed well-developed hexagonal plates with narrow size distribution (2–4 μm) and were in line with the typical morphology for hydrotalcite-like materials. The optimal equilibrium of acid-base property and high crystallinity made the LDO Mg/Al 4.0 an excellent catalyst in the synthesis of propylene glycol methyl ether (PM) from methanol and propylene oxide (PO).[Figure not available: see fulltext.][InlineMediaObject not available: see fulltext.] [ABSTRACT FROM AUTHOR]

Densities and viscosities at T = 293.15, 298.15 and 303.15 K in the binary liquid mixtures of ethyl tert-butyl ether (ETBE) with propylene glycol monomethyl ether (PM), dipropylene glycol monomethyl ether (DPM) and tripropylene glycol monomethyl ether (TPM) have been measured over the entire mixture compositions. These data have been used to compute the excess molar volumes (V E), the excess energies of activation for viscous flow ΔG*E, the deviations in the viscosity (Δη) from a mole fraction average and the Grunberg–Nissan interaction parameters (d12). The values of V E, Δη, ΔG*E and d12 are negative over the entire range of composition for all the studied binary mixtures. The changes of V E, Δη, ΔG*E and d12 with variations in the composition and the chain-length of the alkyl groups in the alkoxypropanol molecules are discussed in terms of the intermolecular interactions. [ABSTRACT FROM AUTHOR]

Abstract: Propylene glycol monomethyl ether (PM), along with its acetate, is the most widely used of the propylene glycol ether family of solvents. The most common toxic effects of PM observed in animal studies include sedation, very slight alpha2u-globulin mediated nephropathy (male rats only) and hepatomegally at high exposures (typically>1000ppm). Sedation in animal studies usually resolves within a few exposures to 3000ppm (the highest concentration used in subchronic and chronic inhalation studies) due to the induction of metabolizing enzymes. Data from a variety of pharmacokinetic and mechanistic studies have been incorporated into a PBPK model for PM and its acetate in rats and mice. Published controlled exposure and workplace biomonitoring studies have also been included for comparisons of the internal dosimetry of PM and its acetate between laboratory animals and humans. PM acetate is rapidly hydrolyzed to PM, which is further metabolized to either glucuronide or sulfate conjugates (minor pathways) or propylene glycol (major pathway). In vitro half-lives for PM acetate range from 14 to 36min depending upon the tissue and species. In vivo half-lives are considerably faster, reflecting the total contributions of esterases in the blood and tissues of the body, and are on the order of just a few minutes. Thus, very little PM acetate is found in vivo and, other than potential portal of entry irritation, the toxicity of PM acetate is related to PM. Regardless of the source for PM (either PM or its acetate), rats were predicted to have a higher Cmax and AUC for PM in blood than humans, especially at concentrations greater than the current ACGIH TLV of 100ppm. This would indicate that the major systemic effects of PM would be expected to be less severe in humans than rats at comparable inhalation exposures. [Copyright &y& Elsevier]

In response to the First Industrial Fluid Simulation Challenge issued by the Computational Molecular Science and Engineering Forum (CoMSEF) of American Institute of Chemical Engineers (AIChE), we have performed osmotic molecular dynamics (OMD) simulations on model mixtures representing propylene + dimethyl ether and nitroethane + propylene glycol monomethyl ether (PGME) at each of two temperatures. The models are standard force-field models available in the literature for site–site interactions between heavy nuclei. Coulombic and Lennard–Jones (LJ) potentials are defined at each site and cross Lennard–Jones interactions are obtained from the Lorentz–Berthelot combining rules. OMD simulations yield the activity coefficients for each component in the mixture at the specified composition. However, because values of individual activity coefficients are less accurate for smaller mole fractions, when the composition difference across the membrane is large, we have chosen to impose thermodynamic consistency to smooth the data over the whole composition range. This is done by fitting simulated values of both activity coefficients simultaneously to the Wilson activity coefficient correlation. Pxy diagrams and data are then reported at the desired compositions for both systems at two different temperatures using the smoothed activity coefficients. [Copyright &y& Elsevier]

The objective of this study was to establish the possible occurrence of eye irritation and subjective symptoms in human volunteers exposed to propylene glycol monomethyl ether (PGME) vapour at concentrations of 0, 100 and 150 ppm. Testing was conducted in 12 healthy male volunteers using a repeated measures design. Each subject was exposed for 2.5 h to each of the three exposure conditions that were spaced 7 days apart. The exposure sequences were counterbalanced and the exposure to the test substance and the effect measurements were conducted in a double-blind fashion. During all exposure sessions, 20 ppm diethyl ether was used as a ‘masking agent’ for vapour exposure. Measurements of pre- and post exposure eye redness, corneal thickness, tear film break-up time, conjunctival epithelial damage, blinking frequency, and subjective ratings on discomfort were used to evaluate the possible irritating effects of PGME. The results indicated no significant treatment effects for any of the objective parameters. Results of the subjective ratings indicated very slight effects on the eyes in the 150 ppm PGME condition only. No significant effects of treatment were found for the remaining questions concerning the perceived intensity of the smell in the room, the (un)pleasantness of the smell, the perceived effects on the skin, effects on the throat, shivering, muscle aching, and intestinal cramps. In conclusion, the results of the present study indicated minimal subjective eye effects at 150 ppm only, and no impact on the objective measures of eye irritation at either of the two exposure levels. It was concluded that the no adverse effect concentration for eye irritation due to PGME vapour was at least 150 ppm. [Copyright &y& Elsevier]

Objective. The two isomers propylene glycol monomethyl ether [PGME-α (1-methoxy-2-propanol, M2P) and PGME-β (2-methoxy-1-propanol)] have different toxicities due to the different ways they are metabolised. The higher toxicity of PGME-β has been attributed to the formation of 2-methoxypropionic acid (2-MPA) as a metabolite of primary alcohol. Six healthy male volunteers were exposed to PGME-α vapour (15, 50 and 95 ppm) with and without respiratory protection for 6 h, including a 30-min break. They were also exposed to PGME-α liquid (10% or 30% in water), via one hand, for 30 min or 1 h. Commercial products of M2P always contain a small quantity of the β isomer, and GC analysis has shown that the product used for this human volunteer exposure contained approximately 0.3% of the β isomer. The objective of this study was to determine the levels of 2-MPA in urine after these exposures to 99.7% PGME-α. Method. An analytical method developed by Laitinen [6] was used for the determination of 2-MPA in the urine of exposed volunteers. Results. End exposure levels of 2-MPA were found to reach from 1.19 to 3.29 mg/l for inhalation and dermal exposure to PGME-α vapour and from under the detection limit to 2.10 mg/l for exposure of one hand in PGME-α liquid. 2-MPA concentrations in urine samples from a non-exposed person or from a person exposed to PGME-α vapour at 15 ppm (inhalation and dermal exposure) and also from a person exposed to PGME-α vapour up to 95 ppm with respiratory protection (dermal-only exposure) all varied from under the detection limit to 0.30 mg/l and are then not significant. [ABSTRACT FROM AUTHOR]

A series of inhalation studies with propylene glycol monomethyl ether (PGME) vapor were undertaken to characterize its subchronic toxicity in mice and chronic toxicity/oncogenicity in rats and mice. Groups of male and female Fischer 344 rats and B6C3F1 mice were exposed to 0,300, 1,000, or 3,000 ppm vapor from 1 week to 2 years. Primary treatment-related effects included: initial sedation of animals exposed to 3,000 ppm and its subsequent resolution correlating with induction of hepatic mixed function oxidase activity and S-phase DNA synthesis; elevated mortality in high-exposure male rats and mice (chronic study); elevated deposition of alpha[sub 2U]-globulin (α[sub 2U]-G) and associated nephropathy and S-phase DNA synthesis in male rat kidneys; accelerated atrophy of the adrenal gland X-zone in female mice (subchronic study only); and increased occurrence and/or severity of eosinophilic foci of altered hepatocytes in male rats. No toxicologically relevant statistically significant increases in neoplasia occurred in either species. A numerical increase in the incidence of kidney adenomas occurred in intermediate-exposure male rats; however, the association with α[sub 2U]-G nephropathy, a male rat specific effect, indicated a lack of relevance for human risk assessment. [ABSTRACT FROM AUTHOR]

• Densities of six dilute solutions of three ILs with two solvents were measured. • Compounds are [Emim][NTf 2 ], [Bmim][NTf 2 ], [Bmmim][NTf 2 ], DEC and PEGMME. • Interactions of ion-ion and ion–solvent were discussed. • Influence of methyl and methylene introduction on the properties were discussed. Different groups have important influence on the interaction between molecules. In order to understand the effect of group introduction on the molecular interaction in solution, the densities of six diluted solutions including three ionic liquids (ILs) and two organic solvents were measured. The groups include methylene and methyl. The three ILs are 1-ethyl-3-methylimidazolium bis[(trifluoromethyl)sulfonyl]imide ([Emim][NTf 2 ]), 1-butyl-3-methylimidazolium bis[(trifluoromethyl)sulfonyl]imide ([Bmim][NTf 2 ]), and 1-butyl-2,3-dimethylimidazolium bis[(trifluoromethyl)sulfonyl]imide ([Bmmim][NTf 2 ]). The organic solvents are diethyl carbonate (DEC) and propylene glycol monomethyl ether (PEGMME). The measured densities were used to calculate apparent molar volumes, V ϕ / cm 3 · m o l - 1 , from 293.15 to 328.15 K with ± 0.02 K. Then, the fitting of infinite dilution apparent molar volumes, V ϕ 0 / cm 3 · m o l - 1 , were obtained by using the calculated values of apparent molar volumes. The effects of different structures of ILs cations and organic solvents on the apparent molar volume, infinite dilution apparent molar volume, limiting apparent molar expansibility and thermal expansibility coefficient were discussed. [ABSTRACT FROM AUTHOR]

This study evaluated propylene glycol monomethyl ether (PGME) in a rat 2-generation reproduction study, which included non-traditional study end points, such as sperm count and motility, developmental landmarks, estrous cyclicity, and weanling organ weights. Groups of 30 male and 30 female Sprague-Dawley rats (6-weeks-old) were exposed to 0, 300, 1000, or 3000 ppm of PGME vapors via inhalation for 6 hours/day, 5 days/week prior to mating, and 6 hours/day, 7 days/week during mating, gestation, and lactation, for 2 generations. These concentrations corresponded to estimated oral equivalent doses of 0, 396, 1325, or 3974 mg/kg/day. At 3000 ppm, toxicity in the P1 and P2 adults was marked, as evidenced by sedation during and after exposure, and mean body weights which were as much as 21% lower than controls. This marked parental toxicity was accompanied by lengthened estrous cycles, decreased fertility, decreased ovary weights, and histologic ovarian atrophy in maternal rats. In the offspring from these dams, decreased body weights, reduced survival and litter size, slight delays in puberty onset, and histologic changes in liver and thymus in the F1 and F2 offspring were observed. The nature of the reproductive/neonatal effects and their close individual animal correlation with decreased maternal body weights suggested that these effects were secondary to general toxicity and/or nutritional stress. No such reproductive/neonatal effects were observed at 1000 ppm, a concentration which caused less marked, but significant body weight effects without sedation. There were no treatment-related effects of any kind noted at 300 ppm of PGME. Therefore, the no-observable-effect level (NOEL) for reproductive/neonatal effects was 1000 ppm, and that for parental toxicity was 300 ppm. [ABSTRACT FROM PUBLISHER]

Objective: In order to identify users of PGME and potential exposures, a chemical registration database maintained in Switzerland was analysed. Method: The database contains information on the composition of products (qualitative and quantitative), the field of use, the year of registration and the domain of commercial applications (public or professional). Results: Identification of potential exposures in Switzerland was carried out. Out of a total of 150,000 products, 2334 were found to contain PGME and most contained between 1% and 10% PGME. There was a great increase in the number of products declared between 1983 and 1991. The principal fields of use were in inks, varnishes and paints. [ABSTRACT FROM AUTHOR]

Objective: To establish a method for the determination of 1-methoxy-2-propanol in urine using headspace solid phase micro-extraction coupled with gas chromatography. Methods: The 1-methoxy-2-propanol was enriched by headspace solid phase micro-extraction fiber coated with carbene/polydimethylsiloxane (CAR/PDMS) . Single factor rotation method was used to optimize the conditions of extraction temperature, salt amount, and extraction time. The separation was performed on DB-5 (30 m×0.32 mm×0.25 μm) capillary column and detected with flame ionization detector. The quantification was based on the standard curve. Results: The concentration of 1-methoxy-2-propanol in urine was linear in the range of 0.50-10.0 mg/L, and the linear correlation coefficient was 0.9993. The detection limit of the method was 0.14 mg/L, and the limit of quantification was 0.45 mg/L. The recovery was 85.8% to 104.7%, and the RSD of intra- and inter-batch precision were 3.25%-6.65% and 0.81%-3.96%, respectively. Conclusion: The method is high sensitivity and simple operation, and is suitable for the determination of 1-methoxy-2-propanol in urine of occupational exposure population.