Depending on where the nitronium group or the alpha complexes of the reaction is on the ring, determines whether the product will be meta, para or ortho. The energy required for ortho and para positions are much lower than if the atom is in a meta position. The reaction below illustrates the different products that can be formed: The bromine atom that is present in the reaction is an ortho-para director because it favors the formation of the product to be either ortho or para instead of being in a meta position. In addition, the presence of an electron withdrawing group or electron releasing group aids in determining whether the products will be in a meta, ortho or para position. The presence of an electron releasing group, in this reaction it is the bromine atom, the nitronium group will be attached in wither the ortho or para position.
Bromination is a type of electrophilic aromatic substitution reaction where one hydrogen atom of benzene or benzene derivative is replaced by bromine due to an electrophilic attack on the benzene ring. The purpose of this experiment is to undergo bromination reaction of acetanilide and aniline to form 4-bromoacetanilide and 2,4,6-tribromoaniline respectively. Since -NHCOCH3 of acetanilide and -NH2 of aniline are electron donating groups, they are ortho/para directors due to resonance stabilized structure. Even though the electron donating groups activate the benzene ring, their reactivities are different and result in the formation of different products during bromination. In acetanilide, the lone pair of the nitrogen is delocalized into the
Introduction Grignard reagent is considered as an organometallic compound or it's the composition of electrophilic and nucleophilic that electrophilic is the carbon atom of organic halide which is directly attached to the halogen, it's reactivity can be switched to the nucleophilic reactivity by conversion an organomagnesium halide. It has the general formula of (RMgX) and it has a general nomenclature which it's called magnesium alkyl halide. We can get Grignard reagent by adding one of solutions of alkyl halide to an ether, slowly. Then, garbling them that's leads to the boiling of solution and magnesium becomes disappeared so, we can get the reagent. Grignard reagent is also considered as the best known reagent of all organometallic compounds, as carbon atom is connected to a metal atom which may be
The positive or partially positive atom is referred to as an electrophile. The whole molecule which the electrophile and the leaving group are part of is called the substrate. The most general form of the reaction is represented as the following: Nuc: + R-LG → R-Nuc + LG: The lone pair on the nucleophile would attack the (R-LG) substrate, forming a new bond with the (R) resulting in the (LG) leaving the substrate with a lone pair. The product formed after the nucleophilic attack is (R-Nuc). After the nucleophilic substitution, the nucleophile can be neutral or carry a negative charge while the substrate can be neutral or positively charged.
P. agarwal and co-workers work for protein chemical modification by conducting a pictet-spengler reaction between aldehydes and alkoxyamines. This forms an oxyiminium ion as an intermediate that eventually undergoes intramolecular C-C bond with indole nucleophile to form an oxacarboline product. As compared to the oxime and hydrazone conjugates, the oxacarbolines are very much stable towards the hydrolysis under physiological relevant conditions as depicted by their experiment. In order to use this strategy for site specific chemical modification of formylglycine and glyoxalglycine-functionalized, they use an aldehyde-tagged variant of the Herceptin( a therapeutic monoclonal antibody). All the experiments performed by them showed that the Pictet-spengler reaction has a bright future in the research for the
An electrophile means an electron seeking species. Haloarenes will undergo the usual benzene ring reactions such as nitration, halogenation, Friedel-Crafts reactions and sulphonation. Before discussing all the electrophilic reactions, we need to understand the nature of Reaction of Haloarenes with respect to the attack of an electrophile. We know that haloarenes are electron-rich compounds. Therefore, they can undergo electrophilic substitution reaction and the attacking species, in this case, will be an electrophile.
One noticeable exception is the so-called “Atwal modification” of the Biginelli reaction. In this scheme, an enone(a) is first condensed with a suitable protected urea or thiourea derivative(b) under almost neutral conditions. Deprotection of the resulting 1,4-dihydropyrimidine(c) with HCl or TFA leads to the desired DHPMs.20 Scheme-3: Shutalev et al described another approach to DHPMs synthesis. This synthesis is based on the condensation of readily available R-tosylated (thio)ureas(a) with the enolates of acetoacetates or 1,3-dicarbonyl compounds. The resulting hexahydropyrimidines(b) need not to be isolated and can be converted directly into DHPMs.
The goal of the experiment is to synthesize a bromohexane compound from 1-hexene and HBr(aq) under reflux conditions and use the silver nitrate and sodium iodide tests to determine if the product is a primary or secondary hydrocarbon. The heterogeneous reaction mixture contains 1-hexene, 48% HBr(aq), and tetrabutylammonium bromide and was heated to under reflux conditions. Heating under reflux means that the reaction mixture is heated at its boiling point so that the reaction can proceed at a faster rate. The attached reflux condenser allows volatile substances to return to the reaction flask so that no material is lost. Since alkenes are immiscible with concentrated HBr, tetrabutylammonium bromide is used as a phase-transfer catalyst.
Enantiomers, a type of isomer, are two compounds that are chemically similar, but are arranged as non-superimposable mirror images of each other. Enantiomers tend to have many similar chemical properties, such as melting point and solubility. In this experiment a pair of enantiomers, S-Carvone and R-Carvone
The hydroxyl group (-OH) of NaOH attacks an electrophilic carbon of >N-C=O which as rearrangement gives carbonial . This carbonial abstract proton from water to give NAG. The established over degradation of NAG to 4-MBA was also obseved in alkali condition. Degradation pathway of AN is shown in Fig.3. The isolated degradation products are subjected to Mass studies to obtain their accurate mass fragment patterns.