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At least 19 recordsLinked to original sources
PubMed2002

Short and stereoselective total synthesis of furano lignans (+/-)-dihydrosesamin, (+/-)-lariciresinol dimethyl ether, (+/-)-acuminatin methyl ether, (+/-)-sanshodiol methyl ether, (+/-)-lariciresinol, (+/-)-acuminatin, and (+/-)-lariciresinol monomethyl ether and furofuran lignans (+/-)-sesamin, (+/-)-eudesmin, (+/-)-piperitol methyl ether, (+/-)-pinoresinol, (+/-)-piperitol, and (+/-)-pinoresinol monomethyl ether by radical cyclization of epoxides using a transition-metal radical source.

Intramolecular radical cyclization of suitably substituted epoxy ethers 4a-g using bis(cyclopentadienyl)titanium(III) chloride as the radical source resulted in trisubstituted tetrahydrofurano lignans and 2,6-diaryl-3,7-dioxabicyclo[3.3.0]octane lignans depending on the reaction conditions. The titanium(III) species was prepared in situ from commercially available titanocene dichloride and activated zinc dust in THF. Upon radical cyclization followed by acidic workup, epoxy olefinic ethers 4a-g afforded furano lignans dihydrosesamin 1a, lariciresinol dimethyl ether 1b, acuminatin methyl ether 1e, and sanshodiol methyl ether 1g directly and lariciresinol 1h, acuminatin 1i, and lariciresinol monomethyl ether 1j after removal of the benzyl protecting group by controlled hydrogenolysis of the corresponding cyclized products. The furofuran lignans sesamin 2a, eudesmin 2b, and piperitol methyl ether 2e were also prepared directly by using the same precursors 4a-f on radical cyclization followed by treatment with iodine and pinoresinol 2h, piperitol 2i, and pinoresinol monomethyl ether 2j after controlled hydrogenolysis of the benzyl protecting group of the corresponding cyclized products. Two naturally occurring acyclic lignans, secoisolariciresinol 5h and secoisolariciresinol dimethyl ether 5b, have also been prepared by exhaustive hydrogenolysis of 2h and 2b, respectively.

Alkylation↗
PubMed2004

Degradation of alkyl ethers, aralkyl ethers, and dibenzyl ether by Rhodococcus sp. strain DEE5151, isolated from diethyl ether-containing enrichment cultures.

Twenty strains isolated from sewage sludge were found to degrade various ethers, including alkyl ethers, aralkyl ethers, and dibenzyl ether. In Rhodococcus strain DEE5151, induction of ether degradation needed substrates exhibiting at least one unsubstituted Calpha-methylene moiety as the main structural prerequisite. The cleavage reaction observed with anisole, phenetole, and dibenzyl ether indicates that the initial oxidation occurs at such respective Calpha positions. Diethyl ether-induced strain DEE5151 degraded dibenzyl ether via intermediately accumulated benzoic acid. Phenetole seems to be subject also to another ether-cleaving enzyme. Other strains of this group showed different enzymatic activities towards the substrate classes investigated.

Biodegradation, Environmental↗
PubMed2005

Short-term oral toxicity of butyl ether, ethyl hexyl ether, methyl heptyl ether and 1,6-dimethoxyhexane in male rats and the role of 2-methoxyacetic acid.

A 4-week oral study was conducted in male rats to characterize and compare the toxicity of four aliphatic ethers (butyl ether, BE; ethyl hexyl ether, EHxE; methyl heptyl ether, MHpE; and 1,6-dimethoxyhexane, DMH) which have been proposed as high-cetane diesel additives. Male Sprague-Dawley rats (280+/-20 g) were divided into groups of seven animals each and were administered by gavage low (2mg/kg body weight), medium (20mg/kg) or high (200mg/kg) doses of BE, EHxE, or MHpE, 5 days per week for 4 weeks. Another group of animals was administered DMH at 200mg/kg while the control group received the vehicle (corn oil at 1 ml/100g bw) only. At the end of the treatment period, relative testis weights and thymus weights were significantly decreased in the DMH group but not in animals receiving BE, EHxE, or MHpE. Microscopic examination revealed degeneration of the seminiferous tubules and reduction of sperm density in the epididymides in the DMH treatment group. Urinary creatine/creatinine ratio, a sensitive indicator of testicular damage, was markedly elevated in the DMH treated animals but not in those treated with BE, EHxE, or MHpE. In the bone marrow, DMH caused mild dyserythropoiesis and dysthrombopoiesis, while BE, EHxE, and MHpE produced mild increases in granulocytes and myelocyte/erythrocyte ratio. All four ethers at 200mg/kg caused mild histological changes in the thyroid but no significant modulation in the circulating thyroxin (T4) or triiodothyronine (T3) levels. All four ethers produced hepatic effects at 200mg/kg consisting of mild, adaptive histological changes, increased urinary ascorbic acid output, and elevation in the activities of one or more xenobiotic metabolizing enzymes (benzyloxyresorufin-O-dealkylase, UDP-glucuronosyltransferase, glutathione-S-transferases). The level of 2-methoxyacetic acid (MAA), a known testicular and developmental toxin, was significantly increased in the urine and plasma of animals treated with DMH but not in those administered the high dose BE, EHxE, or MHpE. Amomg the individual rats treated with DMH, the MAA level appeared to correlate with the severity of toxicity such as testicular and thymic weights, and urinary creatine/creatinine ratio. It is concluded that BE, EHxE, and MHpE differed from DMH in that they did not produce testicular or thymic toxicity. All four ethers at high dose caused changes to the thyroid, liver and bone marrows that were mild and adaptive in nature. MAA appeared to be the proximal toxicant in DMH treated animals but the route by which DMH is metabolized to MAA remains to be elucidated.

Acetates↗
PubMed2000

Difference spatial distribution function analysis of aqueous solutions. II. Hydration structures of dimethyl ether, 180 degrees ethyl methyl ether and 0 degree ethyl methyl ether solutions.

Monte Carlo simulations are systematically presented to demonstrate the influence of the hydrophobic group's steric bulk on hydration structure. We have simulated a dimethyl ether (DME), two conformations for ethyl methyl ether (0 degree EME and 180 degrees EME), and 0 degree ethanol solutions. Spatial distribution function (SDF), goo(x,y,z) and difference SDF (DSDF), delta goo(x,y,z), obtained from MC simulation in an infinitely dilute aqueous solution of ether show the three-dimensional probability of an atom-atom pair distribution between solute and solvent atoms. Based on the results of SDF in an infinitely dilute aqueous solution of ether, the distribution of hydration water molecules can be divided into hydrogen acceptor (HA) and hydrophobic hydration (HH), regions, and the spatial orientation of the hydrogen-bonded water in the HA region is found to form a triple-layer structure, as it does in alcohol solutions. From the results of an analysis of the DSDF delta goo(x,y,z) between the SDFs of EME and DME, it is apparent that the distribution changes of hydration water molecules in ether solutions are essentially similar to those in the alcohol solutions. Further, we show that the hydration water molecules are distributed mainly in the stable area in the binding energy's (BE) contour maps for each region.

Algorithms↗
PubMed2001

Biodegradation of ethyl t-butyl ether (ETBE), methyl t-butyl ether (MTBE) and t-amyl methyl ether (TAME) by Gordonia terrae.

Gordonia terrae strain IFP 2001 was selected from activated sludge for its capacity to grow on ethyl t-butyl ether (ETBE) as sole carbon and energy source. ETBE was stoichiometrically degraded to t-butyl alcohol (TBA) and the activity was inducible. A constitutive strain, G. terrae IFP 2007, derived from strain IFP 2001, was also selected. Methyl t-butyl ether (MTBE) and t-amyl methyl ether (TAME) were not used as carbon and energy sources by the two strains, but cometabolic degradation of MTBE and TAME was demonstrated, to TBA and t-amyl alcohol (TAA) respectively, in the presence of a carbon source such as ethanol. No two-carbon compound was detected during growth on ETBE, but formate was produced during cometabolic degradation of MTBE or TAME. A monooxygenase was involved in the degradation of ethers, because no degradation of ETBE was observed under anaerobic conditions and the presence of a cytochrome P-450 was demonstrated in G. terrae IFP 2001 after induction by cultivation on ETBE.

Actinomycetales↗
PubMed1997

Biodegradation of the gasoline oxygenates methyl tert-butyl ether, ethyl tert-butyl ether, and tert-amyl methyl ether by propane-oxidizing bacteria.

Several propane-oxidizing bacteria were tested for their ability to degrade gasoline oxygenates, including methyl tert-butyl ether (MTBE), ethyl tert-butyl ether (ETBE), and tert-amyl methyl ether (TAME). Both a laboratory strain and natural isolates were able to degrade each compound after growth on propane. When propane-grown strain ENV425 was incubated with 20 mg of uniformly labeled [14C]MTBE per liter, the strain converted > 60% of the added MTBE to 14CO2 in < 30 h. The initial oxidation of MTBE and ETBE resulted in the production of nearly stoichiometric amounts of tert-butyl alcohol (TBA), while the initial oxidation of TAME resulted in the production of tert-amyl alcohol. The methoxy methyl group of MTBE was oxidized to formaldehyde and ultimately to CO2. TBA was further oxidized to 2-methyl-2-hydroxy-1-propanol and then 2-hydroxy isobutyric acid; however, neither of these degradation products was an effective growth substrate for the propane oxidizers. Analysis of cell extracts of ENV425 and experiments with enzyme inhibitors implicated a soluble P-450 enzyme in the oxidation of both MTBE and TBA. MTBE was oxidized to TBA by camphor-grown Pseudomonas putida CAM, which produces the well-characterized P-450cam, but not by Rhodococcus rhodochrous 116, which produces two P-450 enzymes. Rates of MTBE degradation by propane-oxidizing strains ranged from 3.9 to 9.2 nmol/min/mg of cell protein at 28 degrees C, whereas TBA was oxidized at a rate of only 1.8 to 2.4 nmol/min/mg of cell protein at the same temperature.

Bacteria↗
PubMed2006

Preparation and characterization of monovalent cation selective sulfonated poly(ether ether ketone) and poly(ether sulfone) composite membranes.

Highly charged cation permeable composite membranes were prepared by blending of sulfonated poly(ether sulfone) (SPES) with sulfonated poly(ether ether ketone) (SPEEK) in 0 to 90% weight ratio, to adjust the hydrophobic properties and ion selective nature. Extent of sulfonation was confirmed by 1H NMR and ion exchange capacity and degree of sulfonation depending on blending composition. These membranes were characterized as a function of weight fraction of SPEEK by recording ion-exchange capacity, water uptake, thermogravimetric analysis, membrane conductivity and membrane potential in equilibration with different electrolytic solutions. Membrane permselectivity and solute flux were estimated using these data on the basis of non-equilibrium thermodynamic principles and for observing the selectivity of different membranes for mono- or bivalent counter-ions. It was observed that relative selectivity for monovalent in comparison to bivalent counter-ions were increased with the decrease in SPEEK content in the composite membrane matrix. The range of SPEEK content in the blend from 60 to 80% appears the most suitable for the selective separation of monovalent ions from bivalent ions. Furthermore, highly charged nature and stabilities of these membranes extend their applications for the electro-assisted separations of similarly charged ions as well as other electro-membrane processes.

Journal Article↗
PubMed1975

Inhalation carcinogenicity of alpha halo ethers. I. The acute inhalation toxicity of chloromethyl methyl ether and bis(chloromethyl)ether.

A range of acute studies were performed with chloromethyl methyl either (CMME) and bis(chloromethyl)ether (BCME), including 14-day LC50's following single seven-hour inhalation exposures. The LC50's for CMME were 55 ppm for rats and 65 ppm for hamsters. The LC50's for BCME were 7 ppm for both species. All animals showed characteristic changes of acute irritation of the respiratory tract manifested by congestion, edema, and hemorrhage. Severe shortening of life span was seen in 30-day exposures of rats to CMME and in all studies with BCME. Incidences of mucosal changes, including atypia, were generally increased in a dose-related manner in both species. The carcinogenicity of BCME in these range finding experiments was demonstrated by a skin cancer in a rat after three exposures and a nasal tumor in a hamster after one exposure to 1 ppm BCME.

Animals↗
PubMed1996

[Early contributions from Erlangen to the theory and practice of ether and chloroform anesthesia. 1. Heyfelder's clinical trial with ether and chloroform].

The era of modern anaesthesia in Germany began on January 24th, 1847. This day, professor in ordinary Johann Ferdinand Heyfelder anaesthetized a patient with sulphuric ether in the clinic of surgery and ophthalmology of the University of Erlangen. By March 17th, 1847, Heyfelder had performed 121 surgical procedures under ether. The operations in majority were teeth-extractions, and a few more complex operations such as the treatment of a harelip or of lip cancer or the resection of the shoulder joint. Heyfelder described in detail 108 of these inhalations in a little book entitled The experiments with sulphuric ether. This monograph published in March, 1847, represents one of the first complete dissertations on sulphuric ether in the German literature. In a special chapter he analyzed the development of various physiological and psychological parameters during etherization. Heyfelder also examined blood and urine of some etherized patients and reported that he did not find any important or specific alterations. In 1847, Heyfelder was probably the first to apply salt-ether in man. After 4 administrations he concluded that salt ether acted more quickly but shorter than sulphuric ether. Advantageous were its application without problems and ease of induction. Disadvantageous were its high volatility, its price and the difficulty of getting it in a pure form. From December, 1847, on Heyfelder started to use chloroform. He was now able to perform more major operations, for example, the total resection of the hip-joint. In his book The experiments with sulphuric ether, salt ether, and chloroform he describes a great number of anaesthetic administrations using these 3 agents. In his summary Heyfelder concluded, that chloroform was undoubtly superior to sulphuric ether mainly because it was a quicker acting and longer lasting agent and leads to deeper narcosis. Moreover its application was much easier for it needed no special apparatus. However, because of its great anaesthetic potency, Heyfelder particularly demanded great caution in the application of chloroform. Explicitely he expected an assistant for chloroformizations, whose only duty was to supervise the inhalations and the patient--a forerunner of the modern specialized anaesthesiologist.

Anesthesiology↗
PubMed2003

Ether-linked analogue of 2-arachidonoylglycerol (noladin ether) was not detected in the brains of various mammalian species.

2-Eicosa-5',8',11',14'-tetraenylglycerol (2-AG ether, HU310, noladin ether) is a metabolically stable ether-linked analogue of 2-arachidonoylglycerol (2-AG), an endogenous cannabinoid receptor ligand. 2-AG ether has been used as a valuable experimental tool by a number of investigators. Recently, several groups reported that 2-AG ether is present in mammalian brains. We examined in detail whether 2-AG ether actually exists in the brains of various mammalian species. We found that 2-AG ether is not present, at least in an appreciable amount, in the rat brain by gas chromatography-mass spectrometry analysis and fluorometric high performance liquid chromatography analysis. The level of 2-AG ether in the rat brain was below 0.2 pmol/g brain, if at all present. Similar results were obtained for the mouse brain, hamster brain, guinea-pig brain and pig brain. The fact that 2-AG ether was not detected in the brains of various mammalian species is consistent with the fact that an ether bond is formed through enzymatic replacement of the fatty acyl moiety of 1-acyl dihydroxyacetone phosphate by a fatty alcohol, the resultant 1-O-alkyl dihydroxyacetone phosphate being a common intermediate of the biosynthesis of ether-linked lipids in mammalian tissues. It is rather questionable whether 2-AG ether is present in appreciable amounts in the brain and acts as an 'endogenous' cannabinoid receptor ligand.

Animals↗
PubMed2001

Amended final report on the safety assessment of PPG-40 butyl ether with an addendum to include PPG-2, -4, -5, -9, -12, -14, -15, -16, -17, -18, -20, -22, -24, -26, -30, -33, -52, and -53 butyl ethers.

The Polypropylene Glycol (PPG) Butyl Ethers function as skinand hair-conditioning agents in cosmetics. Intestinal absorption of the PPG Butyl Ethers was inversely proportional to the molecular weight. In general, the toxicity of the PPG Butyl Ethers decreased as the molecular weight increased. In acute studies, moderate intraperitoneal (IP) doses of various PPG Butyl Ethers caused convulsive seizures in mice and anesthetized dogs, and large oral doses caused decreased activity, anuria, renal tubular swelling and necrosis, and hepatic swelling and necrosis. PPG-2 Butyl Ether vapors were nontoxic by the inhalation route. PPG-2 Butyl Ether was nontoxic in short-term feeding and dermal exposure studies in rats. In animal irritation studies, PPG-2 Butyl Ether caused minor, transient erythema and desquamation; in addition, erythema, edema, ecchymosis, necrosis, and other changes were observed during an acute percutaneous study. PPG-2 Butyl Ether also caused minor to moderate conjunctival irritation and minor corneal injury. PPG-2 Butyl Ether when dermally applied was nontoxic to pregnant rats and was nonteratogenic at doses up to 1.0 ml/kg/day. PPG BE800 at concentrations of 0.001% to 0.26% in feed was noncarcinogenic to rats after 2 years of treatment. In clinical studies, PPG BE800 was nonirritating and nonsensitizing to the skin when tested using 200 subjects. PPG-40 Butyl Ether was neither an irritant nor a sensitizer in a repeat-insult patch test using 112 subjects. Although clinical testing did not indicate significant skin irritation is produced by these ingredients, the animal test data did indicate the potential that these ingredients can be irritating. Therefore, it was concluded that the PPG Butyl Ethers can be used safely in cosmetic products if they are formulated to avoid irritation. Data on the component ingredients, Propylene Glycol, PPG, and n-Butyl Alcohol, from previous cosmetic ingredient safety assessments were also considered and found to support the safety of PPG Butyl Ethers.

Animals↗
PubMed2005

Inhibition of diethyl ether degradation in Rhodococcus sp. strain DEE5151 by glutaraldehyde and ethyl vinyl ether.

Alkyl ether-degrading Rhodococcus sp. strain DEE5151, isolated from activated sewage sludge, has an activity for the oxidation of a variety of alkyl ethers, aralkyl ethers and dibenzyl ether. The whole cell activity for diethyl ether oxidation was effectively inhibited by 2,3-dihydrofurane, ethyl vinyl ether and glutaraldehyde. Glutaraldehyde of less than 30 microM inhibited the activity by a competitive manner with the inhibition constant, K(I) of 7.07+/-1.36 microM. The inhibition type became mixed at higher glutaraldehyde concentrations >30 microM, probably due to the inactivation of the cell activity by the Schiff-base formation. Structurally analogous ethyl vinyl ether inhibited the diethyl ether oxidation activity in a mixed manner with decreasing the apparent maximum oxidation rate, v(max)(app), and increasing the apparent Michaelis-Menten constant, K(M)(app). The mixed type inhibition by ethyl vinyl ether seemed to be introduced not only by the structure similarity with diethyl ether, but also by the reactivity of the vinyl ether with cellular components in the whole cell system.

Biodegradation, Environmental↗
PubMed1982

NTP Carcinogenesis Bioassay of Bis(2-chloro-1-methylethyl)ether (~70%) (CAS No. 108-60-1) Containing 2-Chloro-1-methylethyl(2-chloropropyl)ether (~30%) (CAS No. 83270-31-9) in B6C3F1 Mice (Gavage Study).

Bis(2-chloro-1-methylethyl) ether is a beta-haloether that has been used extensively in paint and varnish removers, spotting agents, and cleaning solutions. BCMEE has also been used as an intermediate in the manufacture of dyes, resins, and pharmaceuticals and has been added to soap solutions to aid in textile cleaning. Bis (2-chloro-1- methylethyl) ether has been a by-product in the manufacture of propylene oxide and propylene glycol. It is the active ingredient of a nematocide developed and used on field crops in Japan. A NTP Carcinogenesis bioassay of bis (2-chloro- 1-methylethyl) ether (~70%), containing ~30% 2-chloro-1- methylethyl (2-chloropropyl) ether, was conducted by administering 100 or 200 mg/kg bis (2-chloro- 1-methylethyl) ether in corn oil by gavage 5 times per week for 103 weeks to groups of 50 B6C3F1 mice of each sex. Fifty mice of each sex received corn oil alone and served as vehicle controls. Survival and mean body weights of dosed and control mice of each sex were comparable. The incidence of alveolar/bronchiolar adenomas occurred in a positive dose-related trend for male mice (P<0.05: control 5/50, 10%; low-dose 13/50, 26%; high-dose 11/50, 22%) and for female mice (P<0.02: 1/50, 2%; 4/50, 8%; 8/50, 16%). The number of female mice in the high-dose group with adenomas was significantly (P<0.03) greater than that in controls. The combined incidences in dosed males and in high-dose females were significantly higher (P</=0.04 for males and P</=0.01 for females) than those in the controls (males: 6/50, 12%; 15/50, 30%; 13/50, 26%; females: 1/50, 2%; 4/50, 8%; 10/50, 20%). The incidence of hepatocellular carcinomas (5/50, 10%; 13/50, 26%; 17/50, 34%) and the combined incidence of hepatocellular adenomas and carcinomas (13/50, 26%, 23/50, 46%, 27/50, 54%) in male mice were statistically significant by the trend tests (P<0.01) and the incidences in the high-dose group were significantly higher than those in the controls (P<0.01). Metastases to the lung occurred in 1/50 control, 4/50 low-dose, 3/50 high-dose male mice. Fatty metamorphosis was found in increased incidence in the livers of dosed male mice (control 2/50; 16/50 low-dose; 15/50 high-dose). Squamous cell papillomas were found in the stomach or forestomach in two high-dose females, one low-dose male, and one high-dose male. A squamous cell carcinoma was found in the forestomach of a third high-dose female. These tumors were probably related to administration of the test compound, since they are rarely observed in vehicle control and untreated control B6C3F1 mice. Under the conditions of this bioassay, bis (2-chloro-1-methylethyl) ether, containing 2-chloro-1-methylethyl (2-chloropropyl) ether, was carcinogenic for B6C3F1 mice, causing increased incidences of alveolar/bronchiolar adenomas in male and females and hepatocellular carcinomas in males. In addition, the occurrence of a low incidence of squamous cell papillomas or carcinomas in the stomach or forestomach of females (a rare tumor in B6C3F1 mice) was probably associated with the administration of bis(2-chloro-1-methylethyl)ether. Levels of Evidence of Carcinogenicity: Male Mice: Positive Female Mice: Positive Synonyms for bis(2-chloro-1-methylethyl) ether: BCMEE; bis(2-chloroisopropyl) ether; BCPE

Journal Article↗