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Gabriel Synthesis
The Gabriel synthesis is a chemical reaction that transforms primary alkyl halides into primary amines. Traditionally, the reaction uses potassium phthalimide. The reaction is named after the German chemist Siegmund Gabriel. The Gabriel reaction has been generalized to include the alkylation of sulfonamides and imides, followed by deprotection, to obtain amines (see Gabriel synthesis#Alternative Gabriel reagents, Alternative Gabriel reagents). The alkylation of ammonia is often an unselective and inefficient route to amines. In the Gabriel method, phthalimide anion is employed as a surrogate of H2N−. Traditional Gabriel synthesis In this method, the sodium or potassium salt of phthalimide is ''N''-alkylated with a primary alkyl halide to give the corresponding ''N''-alkylphthalimide. Upon workup by acidic hydrolysis the primary amine is liberated as the amine salt. Alternatively the workup may be via the Ing–Manske procedure, involving reaction with hydrazine. This metho ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Siegmund Gabriel
Siegmund Gabriel (7 November 1851 – 22 March 1924) was a German chemist. Scientific career Siegmund Gabriel began studying chemistry at the University of Berlin in 1871. He continued his studies at the University of Heidelberg in 1872 with Professor Robert Wilhelm Bunsen. In 1874, he received his doctorate and then returned to Berlin. He began teaching as an assistant, initially in the inorganic chemistry department, before becoming an associate professor in 1886. Gabriel later turned to organic chemistry in his own research. One of Gabriel’s most significant contributions to organic chemistry was made in 1887, when he discovered the Gabriel Synthesis with his partner James Dornbush. The Gabriel Synthesis is a reaction which synthesizes pure primary amines, involving the reaction of potassium phthalimide with an alkyl halide, followed by hydrolysis. The Gabriel Synthesis was adapted by Gabriel in 1889 to a procedure for the preparation of amino acids. In 1891 Gabriel s ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Acid
In computer science, ACID ( atomicity, consistency, isolation, durability) is a set of properties of database transactions intended to guarantee data validity despite errors, power failures, and other mishaps. In the context of databases, a sequence of database operations that satisfies the ACID properties (which can be perceived as a single logical operation on the data) is called a ''transaction''. For example, a transfer of funds from one bank account to another, even involving multiple changes such as debiting one account and crediting another, is a single transaction. In 1983, Andreas Reuter and Theo Härder coined the acronym ''ACID'', building on earlier work by Jim Gray who named atomicity, consistency, and durability, but not isolation, when characterizing the transaction concept. These four properties are the major guarantees of the transaction paradigm, which has influenced many aspects of development in database systems. According to Gray and Reuter, the IBM Informa ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Delépine Reaction
The Delépine reaction is the organic synthesis of primary amines (4) by reaction of benzyl or alkyl halides (1) with hexamethylenetetramine (2) followed by acid (chemistry), acid hydrolysis of the quaternary ammonium salt (3). It is named after the French chemist Marcel Delépine, Stéphane Marcel Delépine (1871–1965). Advantages of this reaction are selective access to the primary amine without side reactions from easily accessible reactants with short reaction times and relatively mild reaction conditions. Downsides include that the reaction is often performed using chloroform as solvent, which is toxic, and poor atom economy, including the formation of several equivalent (chemistry), equivalents of formaldehyde (a known carcinogen) during quaternary ammonium salt formation. An example is the synthesis of 2-bromoallylamine from 2,3-dibromopropene. Reaction mechanism The benzyl halide or alkyl halide 1 reacts with hexamethylenetetramine to a quaternary ammonium salt 3, each t ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Robinson–Gabriel Synthesis
The Robinson–Gabriel synthesis is an organic reaction in which a 2-acylamino-ketone reacts intramolecularly followed by a dehydration to give an oxazole. A cyclodehydrating agent is needed to catalyze the reaction It is named after Sir Robert Robinson and Siegmund Gabriel who described the reaction in 1909 and 1910, respectively. The 2-acylamino-ketone starting material can be synthesized using the Dakin–West reaction. Reaction mechanism Protonation of the keto moiety (1) is followed by cyclization (2) and dehydration (3), the oxazole ring is less basic that the starting 2-acylamidoketone and so may be readily neutralized (4). Labeling studies have determined that the amide oxygen is the most Lewis basic and therefore is the one included in the oxazole. Modifications Recently, a solid-phase version of the Robinson–Gabriel synthesis has been described. The reaction requires trifluoroacetic anhydride to be used as the cyclodehydrating agent in ethereal solvent and the ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Alkyl Halides
The haloalkanes (also known as halogenoalkanes or alkyl halides) are alkanes containing one or more halogen substituents. They are a subset of the general class of halocarbons, although the distinction is not often made. Haloalkanes are widely used commercially. They are used as flame retardants, fire extinguishants, refrigerants, propellants, solvents, and pharmaceuticals. Subsequent to the widespread use in commerce, many halocarbons have also been shown to be serious pollutants and toxins. For example, the chlorofluorocarbons have been shown to lead to ozone depletion. Methyl bromide is a controversial fumigant. Only haloalkanes that contain chlorine, bromine, and iodine are a threat to the ozone layer, but fluorinated volatile haloalkanes in theory may have activity as greenhouse gases. Methyl iodide, a naturally occurring substance, however, does not have ozone-depleting properties and the United States Environmental Protection Agency has designated the compound a non-ozone l ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Di-tert-butyl-iminodicarboxylate
Di-''tert''-butyl-iminodicarboxylate is an organic compound that can be described with the formula CH3)3COC(O)sub>2NH. It is a white solid that is soluble in organic solvents. The compound is used as a reagent for the preparation of primary amines from alkyl halides. It was popularized as an alternative to the Gabriel synthesis for the same conversion. Amines can also be prepared from alcohols by dehydration using the Mitsunobu reaction.Neelamkavil, Santhosh "Di-tert-butyl-imidocarbonate" e-EROS Encyclopedia of Reagents for Organic Synthesis, 2001, John Wiley & Sons. {{doi, 10.1002/047084289X.rn00488 In the usual implementation the reagent is deprotonated Deprotonation (or dehydronation) is the removal (transfer) of a proton (or hydron, or hydrogen cation), (H+) from a Brønsted–Lowry acid in an acid–base reaction.Henry Jakubowski, Biochemistry Online Chapter 2A3, https://employees.csbsju.edu ... to give the potassium salt, which is ''N''-alkylated. The Boc protecting gr ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Saccharin
Saccharin (''aka'' saccharine, Sodium sacchari) is an artificial sweetener with effectively no nutritional value. It is about 550 times as sweet as sucrose but has a bitter or metallic aftertaste, especially at high concentrations. Saccharin is used to sweeten products such as drinks, candies, cookies, and especially for masking bitter taste of some medicines. Etymology Saccharin derives its name from the word "saccharine", meaning "sugary". The word saccharine is used figuratively, often in a derogative sense, to describe something "unpleasantly over-polite" or "overly sweet". Both words are derived from the Greek word (''sakkharon'') meaning "gravel". Similarly, saccharose is an obsolete name for sucrose (table sugar). Properties Saccharin is heat-stable. It does not react chemically with other food ingredients; as such, it stores well. Blends of saccharin with other sweeteners are often used to compensate for each sweetener's weaknesses and faults. A 10:1 cyclamate–sacch ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Tetrahedron Letters
''Tetrahedron Letters'' is a weekly international journal for rapid publication of full original research papers in the field of organic chemistry. According to the ''Journal Citation Reports'', the journal has a 2020 impact factor of 2.415. Indexing ''Tetrahedron Letters'' is indexed in: References See also *''Tetrahedron In geometry, a tetrahedron (plural: tetrahedra or tetrahedrons), also known as a triangular pyramid, is a polyhedron composed of four triangular faces, six straight edges, and four vertex corners. The tetrahedron is the simplest of all the o ...'' *'' Tetrahedron: Asymmetry'' Chemistry journals Weekly journals Publications established in 1959 Elsevier academic journals {{chem-journal-stub ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Hydrazine
Hydrazine is an inorganic compound with the chemical formula . It is a simple pnictogen hydride, and is a colourless flammable liquid with an ammonia-like odour. Hydrazine is highly toxic unless handled in solution as, for example, hydrazine hydrate (). Hydrazine is mainly used as a foaming agent in preparing polymer foams, but applications also include its uses as a precursor to polymerization catalysts, pharmaceuticals, and agrochemicals, as well as a long-term storable propellant for in-space spacecraft propulsion. Additionally, hydrazine is used in various rocket fuels and to prepare the gas precursors used in air bags. Hydrazine is used within both nuclear and conventional electrical power plant steam cycles as an oxygen scavenger to control concentrations of dissolved oxygen in an effort to reduce corrosion. the world hydrazine hydrate market amounted to $350 million. About two million tons of hydrazine hydrate were used in foam blowing agents in 2015. Hydrazines r ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Hydrolysis
Hydrolysis (; ) is any chemical reaction in which a molecule of water breaks one or more chemical bonds. The term is used broadly for substitution reaction, substitution, elimination reaction, elimination, and solvation reactions in which water is the nucleophile. Biological hydrolysis is the cleavage of biomolecules where a water molecule is consumed to effect the separation of a larger molecule into component parts. When a carbohydrate is broken into its component sugar molecules by hydrolysis (e.g., sucrose being broken down into glucose and fructose), this is recognized as saccharification. Hydrolysis reactions can be the reverse of a condensation reaction in which two molecules join into a larger one and eject a water molecule. Thus hydrolysis adds water to break down, whereas condensation builds up by removing water. Types Usually hydrolysis is a chemical process in which a molecule of water is added to a substance. Sometimes this addition causes both the substance and w ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Gabriel Synthesis Scheme
In Abrahamic religions (Judaism, Christianity and Islam), Gabriel (); Greek: grc, Γαβριήλ, translit=Gabriḗl, label=none; Latin: ''Gabriel''; Coptic: cop, Ⲅⲁⲃⲣⲓⲏⲗ, translit=Gabriêl, label=none; Amharic: am, ገብርኤል, translit=Gabrəʾel, label=none; arc, ܓ݁ܰܒ݂ܪܺܝܐܝܶܠ, translit=Gaḇrīʾēl; ar, جِبْرِيل, Jibrīl, also ar, جبرائيل, Jibrāʾīl or ''Jabrāʾīl'', group="N" is an archangel with power to announce God's will to men. He is mentioned in the Hebrew Bible, the New Testament, and the Quran. Many Christian traditions — including Anglicanism, Eastern Orthodoxy, and Roman Catholicism — revere Gabriel as a saint. In the Hebrew Bible, Gabriel appears to the prophet Daniel to explain his visions (Daniel 8:15–26, 9:21–27). The archangel also appears in the Book of Enoch and other ancient Jewish writings not preserved in Hebrew. Alongside the archangel Michael, Gabriel is described as the guardian angel of ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Chemical Reaction
A chemical reaction is a process that leads to the IUPAC nomenclature for organic transformations, chemical transformation of one set of chemical substances to another. Classically, chemical reactions encompass changes that only involve the positions of electrons in the forming and breaking of chemical bonds between atoms, with no change to the Atomic nucleus, nuclei (no change to the elements present), and can often be described by a chemical equation. Nuclear chemistry is a sub-discipline of chemistry that involves the chemical reactions of unstable and radioactive Chemical element, elements where both electronic and nuclear changes can occur. The substance (or substances) initially involved in a chemical reaction are called reagent, reactants or reagents. Chemical reactions are usually characterized by a chemical change, and they yield one or more Product (chemistry), products, which usually have properties different from the reactants. Reactions often consist of a sequence o ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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