NIOSH REL: TWA 25 ppm (125 mg/m3); ACGIH TLV: TWA for mixed
isomers 25 ppm (adopted).
LogP:
3.630
物理描述:
1,2,4-trimethylbenzene appears as a liquid. Flash point near 130°F. Less dense than water and insoluble in water. Vapors irritate eyes, throat, and nose. Used in dyes and pharmaceuticals.
Metabolism of 1,2,4-TMB in humans and animals occurs by side-chain oxidation to form alcohols and carboxylic acids or hydroxylation to phenols, which are then conjugated with glucuronic acid, glycine, or sulphates prior to urinary excretion ... . Both in laboratory animals and in humans, it was identified that 1,2,4-TMB metabolism is mainly directed towards isomeric dimethylbenzoic acids ... . In rats, 1,2,4-TMB metabolism leads to the production of isomeric dimethylbenzoic acids, of which 3,4-dimethylbenzoic acid was identified as the most prominent in the urine . ... 3,4-Dimethylhippuric acid has been reported to be a minor metabolite in humans ... . This metabolite has also been observed in rabbits, in addition to 2,4-dimethylbenzoic acid... .
Single doses of 1,2,4-trimethylbenzene (124TMB) or 14C-124TMB were administered orally to rats for metabolism and distribution studies. ... A complex mixture of isomeric trimethylphenols, dimethylbenzyl alcohols, dimethylbenzoic acids and dimethylhippuric acids excreted in the urine accounted for more than 81% of the administered dose. The major metabolites were 3,4-dimethylhippuric acid (30.2% dose), 2,4-dimethylbenzyl alcohol (12.7% dose, primarily as sulfate and glucuronide conjugates) and 2,5-dimethylbenzyl alcohol (11.7% dose, primarily as sulfate and glucuronide conjugates).
A study was undertaken of the mercapturic acid metabolism of 1,2,4-trimethylbenzene in the rat. Of three regioisomeric dimethylbenzyl mercapturic acids, i.e. 2,4-, 2,5- and 3,4-dimethylbenzyl isomers, the third isomer was not found in the urinary mercapturic acid isolated by preparative HPLC, from the comparison of NMR spectrum of the isolate with those of authentic specimens. The urinary mercapturate was then assigned to 2,4- and/or 2,5-dimethylbenzyl isomers. The excretion rate of the mercapturic acid was 14-20% of dose as 2,4-dimethylbenzyl isomer.
... the metabolism of pseudocumene (1,2,4-trimethylbenzene) was investigated in rabbits. After oral administration of this compound, urine was collected for several days and analyzed for the presence of acidic metabolites. ... Two major urinary metabolites were identified namely 2,4-dimethylbenzoic acid and 3,4-dimethylhippuric acid. The presence of these acidic metabolites in urine is a good indication of exposure to pseudocumene.
来源:Hazardous Substances Data Bank (HSDB)
毒理性
致癌物分类
对人类不具有致癌性(未被国际癌症研究机构IARC列名)。
No indication of carcinogenicity to humans (not listed by IARC).
来源:Toxin and Toxin Target Database (T3DB)
毒理性
暴露途径
这种物质可以通过吸入被身体吸收。
The substance can be absorbed into the body by inhalation.
来源:ILO-WHO International Chemical Safety Cards (ICSCs)
毒理性
暴露途径
吸入,吞食,皮肤和/或眼睛接触
inhalation, ingestion, skin and/or eye contact
来源:The National Institute for Occupational Safety and Health (NIOSH)
Absorption of 1,2,4,-TMB in humans following respiratory exposure has been reported to range from 56 to 71%... . Trimethylbenzenes have also been reported to be readily absorbed following oral exposure ... . In the bloodstream, approximately 85% of 1,2,4-TMB is bound to red blood cells ... .. As it distributes to tissues in humans, 1,2,4-TMB tends to accumulate in adipose and fatty tissues, brain tissue, and perirenal fat, due to its lipophilicity ...
The objective of this study was to determine the uptake and disposition of inhaled trimethylbenzenes (TMBs) in man. The toxicokinetics were studied in 10 male, healthy volunteers exposed to TMB vapor in an exposure chamber for 2 hr during a work load of 50 W. The subjects were exposed on four occasions to 25 ppm of 1,2,4-TMB, 1,2,3-TMB, and 1,3,5-TMB, and to 2 ppm of 1,2,4-TMB. The TMB isomers were analyzed in blood, urine, and exhaled air by gas chromatography. The relative respiratory uptake was in the range 56-64%. The elimination of TMBs was moderate compared to other aromatic solvents, with a total blood clearance of 0.6-1.0 L per hr per kg. Large volumes of distribution (30-39 liters/kg) and long terminal half-lives of the TMBs in blood (78-120 hr) imply extensive accumulation in adipose tissue. Exhalation during and postexposure accounted for 20-37% of the absorbed amount, whereas the urinary excretion of unchanged TMBs was low (< or = 0.002%). The kinetics of 1,2,4-TMB seemed linear up to 25 ppm. ...
Single doses of 1,2,4-trimethylbenzene (124TMB) or 14C-124TMB were administered orally to rats for metabolism and distribution studies. 14C-124TMB was rapidly and widely distributed throughout the body with the highest levels in adipose tissue. No other preferential uptake of 14C-124TMB by any of the organs or tissues examined was evident. Tissue levels declined rapidly within 24 hr after dosage, with more than 99% of the administered radioactivity recovered in the urine during this period. A complex mixture of isomeric trimethylphenols, dimethylbenzyl alcohols, dimethylbenzoic acids and dimethylhippuric acids excreted in the urine accounted for more than 81% of the administered dose.
来源:Hazardous Substances Data Bank (HSDB)
吸收、分配和排泄
...雄性威斯大鼠在动态吸入室中暴露于25、100或250 ppm的伪品蒸气中6小时。在暴露期间(第1小时和第6小时之间)和暴露后(第6分钟和第6小时之间)收集血液样本。使用气相色谱的顶空技术估计血液中伪品的浓度。在六小时的暴露期间,血液中伪品的浓度在前2小时内迅速增加,然后达到一个平稳期。伪品从血液中的消除遵循开放双室模型。从暴露的动物收集尿液样本,并通过气相色谱与火焰离子化检测器分析代谢物。在大鼠尿液水解后测量到三种代谢物:3,4-二甲基苯甲酸(3,4-DMBA)、2,4-二甲基苯甲酸(2,4-DMBA)和2,5-二甲基苯甲酸(2,5-DMBA)。暴露水平与二甲基苯甲酸浓度之间存在显著线性相关性。伪品生物转化的酶动力学通过林维埃-伯克方程计算。估计了大鼠伪品生物转化的代谢常数,Km(毫克/升)和Vmax(毫克/小时/千克)(3,4-DMBA - Km = 28,Vmax = 96;2,4-DMBA - Km = 7,Vmax = 25;2,5-DMBA - Km = 7,Vmax = 23)。
... Male Wistar rats were exposed to pseudocumene vapors at nominal concentrations of 25, 100 or 250 ppm in the dynamic inhalation chambers for 6 hr. Blood samples were collected during (between 1st and 6 th hr) and after exposure (between 6 th min and 6 th hr). Blood concentrations of pseudocumene were estimated by gas chromatography using the headspace technique. During a six-hour exposure, the concentration of pseudocumene in blood increased rapidly within the first 2 hr reaching then a plateau. The elimination of pseudocumene from blood followed an open two-compartment model. Urine samples were collected from the exposed animals, and metabolites were analyzed by gas chromatography with a flame ionization detector. Three metabolites were measured in the rat urine after hydrolysis: 3,4-dimethylbenzoic acid (3,4-DMBA), 2,4-dimethylbenzoic acid (2,4-DMBA) and 2,5-dimethylbenzoic acid (2,5-DMBA). A significant linear correlation was found between the level of exposure and the concentration of dimethylbenzoic acids. The enzyme kinetics of pseudocumene biotransformation was calculated by Lineweaver-Burk equation. Metabolic constants, Km (mg/L) and Vmax (mg/hr/kg), the parameters for pseudocumene biotransformation by rats were estimated (3,4-DMBA - Km = 28, Vmax = 96; 2,4-DMBA - Km = 7, Vmax = 25; 2,5-DMBA - Km = 7, Vmax = 23).
Oxygenation of Methylarenes to Benzaldehyde Derivatives by a Polyoxometalate Mediated Electron Transfer–Oxygen Transfer Reaction in Aqueous Sulfuric Acid
additional reaction cycles. An electrocatalytic cycle is also feasible. This reaction is possible through the use of an aqueous sulfuric acid solvent, in an aqueous biphasic reaction mode that also allows simple catalyst recycling and recovery. The solvent plays a key role in the reaction mechanism by protonating the polyoxometalate thereby enabling the activation of the methylarenes by an electron transfer
highly efficient, rapid and regioselective protocol was developed for the ring bromination of aromaticcompounds under mild conditions with ammonium bromide as a source of bromine source and Oxone® (potassium peroxysulfate) as an oxidant. No metal catalyst or acidic additive is required. A variety of aromaticcompounds, including methoxy, hydroxy, amino, and alkyl arenes, reacted smoothly to give the
cost. In the second step, OX is selectively produced by a Diels–Alder reaction of 2,3-dimethylbutadiene and acrolein, followed by a Pd/C-catalyzed decarbonylation/aromatization cascade in a one-pot fashion. The sustainable two-stepprocess efficiently produces renewable OX in 79 % overall yield. Analogously, biomass-derived crotonaldehyde and pinacol can also serve as the feedstocks for the production
Photo-induced deep aerobic oxidation of alkyl aromatics
作者:Chang-Cheng Wang、Guo-Xiang Zhang、Zhi-Wei Zuo、Rong Zeng、Dan-Dan Zhai、Feng Liu、Zhang-Jie Shi
DOI:10.1007/s11426-021-1032-7
日期:2021.9
equipment. In this report, photo-induced deep aerobic oxidation of (poly)alkyl benzene to benzene (poly)carboxylic acids was developed. CeCl3 was proved to be an efficient HAT (hydrogen atom transfer) catalyst in the presence of alcohol as both hydrogen and electron shuttle. Dioxygen (O2) was found as a sole terminal oxidant. In most cases, pure products were easily isolated by simple filtration, implying
氧化是自然界和化学工业中生产含氧化学品的主要化学过程。目前,苯甲酸和苯多羧酸(BPCAs)的工业生产主要以聚烷基苯的深度氧化为主,由于形成消耗臭氧层的溴化溴和对生产设备的腐蚀危害,在环境和经济上都有些不利。 . 在这份报告中,开发了(多)烷基苯的光诱导深度有氧氧化为苯(多)羧酸。CeCl 3被证明是在醇存在下作为氢和电子穿梭的有效HAT(氢原子转移)催化剂。双氧 (O 2) 被发现是唯一的终端氧化剂。在大多数情况下,纯产品很容易通过简单的过滤分离,这意味着大规模实施的优势。该反应提供了从天然丰富的石油原料中生产有价值的精细化学品的理想方案。
Begonia plant named ‘Usami N’
申请人:Usami Tatsuo
公开号:USPP022930P2
公开(公告)日:2012-08-07
A new and distinct cultivar of
Begonia
plant named ‘Usami N’, characterized by its upright and mounded plant habit; freely branching habit; leaves with finely-serrated margins; large and showy frilled double flowers with numerous tepals that are pale yellow and various shades of pink in color and held above and beyond the foliar plane; and excellent postproduction longevity.