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Chloromethyl Methyl Ether
Chloromethyl methyl ether (CMME) is a compound with formula CH3OCH2Cl. A colorless liquid, it is a chloroalkyl ether. It is used as an alkylating agent. In organic synthesis, it is used for introducing the methoxymethyl ether (MOM) protecting group, and is thus often called MOM-Cl or MOM chloride. It also finds application as a chloromethylating agent in some variants of the Blanc chloromethylation. Preparation A convenient synthesis of chloromethyl methyl ether ''in situ'' involves the reaction of dimethoxymethane and acetyl chloride in the presence of a Lewis acid catalyst This route affords a methyl acetate solution of chloromethyl methyl ether of high purity. A similar method, using a high-boiling acyl chloride, can be used to prepare pure, dimethoxymethane being the only contaminant. In contrast, the classical procedure reported in ''Organic Syntheses'' employing formaldehyde, methanol, and hydrogen chloride yields material significantly contaminated with the dangero ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Compound (chemistry)
A chemical compound is a chemical substance composed of many identical molecules (or molecular entities) containing atoms from more than one chemical element held together by chemical bonds. A molecule consisting of atoms of only one element is therefore not a compound. A compound can be transformed into a different substance by a chemical reaction, which may involve interactions with other substances. In this process, bonds between atoms may be broken and/or new bonds formed. There are four major types of compounds, distinguished by how the constituent atoms are bonded together. Molecular compounds are held together by covalent bonds; ionic compounds are held together by ionic bonds; intermetallic compounds are held together by metallic bonds; coordination complexes are held together by coordinate covalent bonds. Non-stoichiometric compounds form a disputed marginal case. A chemical formula specifies the number of atoms of each element in a compound molecule, using the stan ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Carcinogen
A carcinogen is any substance, radionuclide, or radiation that promotes carcinogenesis (the formation of cancer). This may be due to the ability to damage the genome or to the disruption of cellular metabolic processes. Several radioactive substances are considered carcinogens, but their carcinogenic activity is attributed to the radiation, for example gamma rays and alpha particles, which they emit. Common examples of non-radioactive carcinogens are inhaled asbestos, certain dioxins, and tobacco smoke. Although the public generally associates carcinogenicity with synthetic chemicals, it is equally likely to arise from both natural and synthetic substances. Carcinogens are not necessarily immediately toxic; thus, their effect can be insidious. Carcinogens, as mentioned, are agents in the environment capable of contributing to cancer growth. Carcinogens can be categorized into two different types: activation-dependent and activation-independent, and each nature impacts their level ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Organochlorides
An organochloride, organochlorine compound, chlorocarbon, or chlorinated hydrocarbon is an organic compound containing at least one covalently bonded atom of chlorine. The chloroalkane class (alkanes with one or more hydrogens substituted by chlorine) provides common examples. The wide structural variety and divergent chemical properties of organochlorides lead to a broad range of names, applications, and properties. Organochlorine compounds have wide use in many applications, though some are of profound environmental concern, with TCDD being one of the most notorious. Physical and chemical properties Chlorination modifies the physical properties of hydrocarbons in several ways. These compounds are typically denser than water due to the higher atomic weight of chlorine versus hydrogen. Aliphatic organochlorides are often alkylating agents as chlorine can act as a leaving group, which can result in cellular damage. Natural occurrence Many organochlorine compounds have been isolate ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Protecting Groups
A protecting group or protective group is introduced into a molecule by chemical modification of a functional group to obtain chemoselectivity in a subsequent chemical reaction. It plays an important role in multistep organic synthesis. In many preparations of delicate organic compounds, some specific parts of their molecules cannot survive the required reagents or chemical environments. Then, these parts, or groups, must be protected. For example, lithium aluminium hydride is a highly reactive but useful reagent capable of reducing esters to alcohols. It will always react with carbonyl groups, and this cannot be discouraged by any means. When a reduction of an ester is required in the presence of a carbonyl, the attack of the hydride on the carbonyl has to be prevented. For example, the carbonyl is converted into an acetal, which does not react with hydrides. The acetal is then called a protecting group for the carbonyl. After the step involving the hydride is complete, the ace ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Alkylating Agents
Alkylation is the transfer of an alkyl group from one molecule to another. The alkyl group may be transferred as an alkyl carbocation, a free radical, a carbanion, or a carbene (or their equivalents). Alkylating agents are reagents for effecting alkylation. Alkyl groups can also be removed in a process known as dealkylation. Alkylating agents are often classified according to their nucleophilic or electrophilic character. In oil refining contexts, alkylation refers to a particular alkylation of isobutane with olefins. For upgrading of petroleum, alkylation produces a premium blending stock for gasoline. In medicine, alkylation of DNA is used in chemotherapy to damage the DNA of cancer cells. Alkylation is accomplished with the class of drugs called alkylating antineoplastic agents. Nucleophilic alkylating agents Nucleophilic alkylating agents deliver the equivalent of an alkyl anion (carbanion). The formal "alkyl anion" attacks an electrophile, forming a new covalent bond be ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Reagents For Organic Chemistry
In chemistry, a reagent ( ) or analytical reagent is a substance or compound added to a system to cause a chemical reaction, or test if one occurs. The terms ''reactant'' and ''reagent'' are often used interchangeably, but reactant specifies a substance ''consumed'' in the course of a chemical reaction. ''Solvents'', though involved in the reaction mechanism, are usually not called reactants. Similarly, ''catalysts'' are not consumed by the reaction, so they are not reactants. In biochemistry, especially in connection with enzyme-catalyzed reactions, the reactants are commonly called substrates. Definitions Organic chemistry In organic chemistry, the term "reagent" denotes a chemical ingredient (a compound or mixture, typically of inorganic or small organic molecules) introduced to cause the desired transformation of an organic substance. Examples include the Collins reagent, Fenton's reagent, and Grignard reagents. Analytical chemistry In analytical chemistry, a reagent ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
United States Government Publishing Office
The United States Government Publishing Office (USGPO or GPO; formerly the United States Government Printing Office) is an agency of the legislative branch of the United States Federal government. The office produces and distributes information products and services for all three branches of the Federal Government, including U.S. passports for the Department of State as well as the official publications of the Supreme Court, the Congress, the Executive Office of the President, executive departments, and independent agencies. An act of Congress changed the office's name to its current form in 2014. History The Government Printing Office was created by congressional joint resolution () on June 23, 1860. It began operations March 4, 1861, with 350 employees and reached a peak employment of 8,500 in 1972. The agency began transformation to computer technology in the 1980s; along with the gradual replacement of paper with electronic document distribution, this has led to a stea ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Emergency Planning And Community Right-to-Know Act
The Emergency Planning and Community Right-to-Know Act of 1986 is a United States federal law passed by the 99th United States Congress located at Title 42, Chapter 116 of the U.S. Code, concerned with emergency response preparedness. On October 17, 1986, President Ronald Reagan signed into law the Superfund Amendments and Reauthorization Act of 1986 (SARA). This act amended the Comprehensive Environmental Response, Compensation, and Liability Act of 1980 (CERCLA), commonly known as Superfund. A free-standing law, the Emergency Planning and Community Right-to-Know Act of 1986 (EPCRA) was commonly known as SARA Title III. Its purpose is to encourage and support emergency planning efforts at the state and local levels and to provide the public and local governments with information concerning potential chemical hazards present in their communities. Background During the early morning hours of December 3, 1984, a Union Carbide plant in a village just South of Bhopal, India rel ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
List Of Extremely Hazardous Substances
This is the list of extremely hazardous substances defined in Section 302 of the U.S. Emergency Planning and Community Right-to-Know Act (42 U.S.C. 11002). The list can be found as an appendix to 40 C.F.R. 355. Updates as of 2006 can be seen on the Federal Register, 71 FR 47121 (August 16, 2006). The data were provided by the United States Environmental Protection Agency (EPA). __NOTOC__ A * Acetone cyanohydrin * Acetone thiosemicarbazide * Acrolein * Acrylamide * Acrylonitrile * Acryloyl chloride * Adiponitrile * Aldicarb * Aldrin * Allyl alcohol * Allylamine * Aluminum phosphide * Aminopterin * Amiton * Amiton oxalate * Ammonia * Amphetamine * Aniline * Aniline, 2,4,6-trimethyl- * Antimony pentafluoride * Antimycin A * ANTU (Alpha-Naphthylthiourea) * Arsenic pentoxide * Arsenous oxide * Arsenous trichloride * Arsine * Azinphos-ethyl * Azinphos-methyl B * Benzal chloride * Benzenamine, 3-(trifluoromethyl)- * Benzenearsonic acid * Benzimidazole, 4,5-dichloro-2-(tri ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Permissible Exposure Limit
The permissible exposure limit (PEL or OSHA PEL) is a legal limit in the United States for exposure of an employee to a chemical substance or physical agent such as high level noise. Permissible exposure limits are established by the Occupational Safety and Health Administration (OSHA). Most of OSHA's PELs were issued shortly after adoption of the Occupational Safety and Health (OSH) Act in 1970. For chemicals, the chemical regulation is usually expressed in parts per million (ppm), or sometimes in milligrams per cubic meter (mg/m3). Units of measure for physical agents such as noise are specific to the agent. A PEL is usually given as a time-weighted average (TWA), although some are short-term exposure limits (STEL) or ceiling limits. A TWA is the average exposure over a specified period, usually a nominal eight hours. This means that, for limited periods, a worker may be exposed to concentration excursions higher than the PEL, so long as the TWA is not exceeded and any applicab ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Occupational Safety And Health Administration
The Occupational Safety and Health Administration'' (OSHA ) is a large regulatory agency of the United States Department of Labor that originally had federal visitorial powers to inspect and examine workplaces. Congress established the agency under the Occupational Safety and Health Act OSH Act, which President Richard M. Nixon signed into law on December 29, 1970. OSHA's mission is to "assure safe and healthy working conditions for working men and women by setting and enforcing standards and by providing training, outreach, education, and assistance". The agency is also charged with enforcing a variety of whistleblower statutes and regulations. OSHA's workplace safety inspections have been shown to reduce injury rates and injury costs without adverse effects on employment, sales, credit ratings, or firm survival. History The Bureau of Labor Standards of the Department of Labor has worked on some work safety issues since its creation in 1922. Economic boom and associated l ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Small Cell Carcinoma
Small-cell carcinoma is a type of highly malignant cancer that most commonly arises within the lung, although it can occasionally arise in other body sites, such as the cervix, prostate, and gastrointestinal tract. Compared to non-small cell carcinoma, small cell carcinoma has a shorter doubling time, higher growth fraction, and earlier development of metastases. Extensive stage small cell lung cancer is classified as a rare disorder. Ten-year relative survival rate is 3.5%; however, women have a higher survival rate, 4.3%, and men lower, 2.8%. Survival can be higher or lower based on a combination of factors including stage, age, gender and race. Types of SCLC Small-cell lung carcinoma has long been divided into two clinicopathological stages, termed ''limited stage'' (LS) and ''extensive stage'' (ES). The stage is generally determined by the presence or absence of metastases, whether or not the tumor appears limited to the thorax, and whether or not the entire tumor burden wit ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
