Heterocyclic compounds are the largest and most varied family of organic compounds. All these, regardless of structure and functionality, may be converted into heterocyclic analogs by replacing one or more of the ring carbon atoms with different elements. Nitrogen containing heterocyclic compounds are one of the most important classes of compounds in the field of organic and agro industries. One of the most interesting nitrogen containing heterocyclic compound in organic chemistry are Quinoline compounds.
Quinolines are a class of organic compound of the heteroaromatic series characterized by a double-ring structure composed of benzene and a pyridine ring fused at two adjacent carbon atoms (Fig 1.1). The benzene ring contains six carbon atoms, while the pyridine ring contains five carbon atoms and a nitrogen atom (compare with the
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1.2 Classical methods for the direct synthesis of polysubstituted quinoline
Synthetically, there are many routes described in the literature for the synthesis of quinoline ring systems. Some of the well-known classical methods are Skraup synthesis 3, Friedlaender synthesis 4, Doebner―Von Miller synthesis 5-7, Pfitzinger reaction 8, Conrad―Limpach Knorr synthesis 9 and Combes method 10.
1. SKRAUP SYNTHESIS 3
The Skraup synthesis is the most important synthetic route for quinoline derivatives. Quinoline (1) is produced when aniline (2), conc. sulfuric acid, glycerol (3) and mild oxidizing agent are heated together 11. The reaction proceeds via dehydration of glycerol to acrolein (4); to which aniline then adds in a conjugate fashion. Acid-catalysed cyclization produces 1, 2-dihydroquinoline which finally gets dehydrogenated to quinoline via an oxidizing agent. It is the best reaction for the ring synthesis of unsubstituted quinoline (Scheme 1.1) 12.
Scheme
This week’s lab was the third and final step in a multi-step synthesis reaction. The starting material of this week was benzil and 1,3- diphenylacetone was added along with a strong base, KOH, to form the product tetraphenylcyclopentadienone. The product was confirmed to be tetraphenylcyclopentadienone based of the color of the product, the IR spectrum, and the mechanism of the reaction. The product of the reaction was a dark purple/black color, which corresponds to literature colors of tetraphenylcyclopentadienone. The tetraphenylcyclopentadienone product was a deep purple/black because of its absorption of all light wavelengths. The conjugated aromatic rings in the product create a delocalized pi electron system and the electrons are excited
Wittig reactions allow the generation of an alkene from the reaction between an aldehyde/ketone and an alkyl halide (derived from phosphonium salt).The mechanism for the synthesis of trans-9-(2-phenylethenyl) anthracene first requires the formation of the phosphonium salt by the addition of triphenylphosphine and alkyl halide. The phosphonium halide is produced through the nucleophilic substitution of 1° and 2° alkyl halides and triphenylphosphine (the nucleophile and weak base). An example is benzyltriphenylphosphonium chloride, which was used in this experiment. The second step in the formation of the of the Wittig reagent, which is primarily called a ylide and derived from a phosphonium halide. In the formation of the ylide, the phosphonium ion in benzyltriphenylphosphonium chloride is deprotonated by the base, sodium hydroxide to produce the ylide as shown in equation 1.
In this experiment, column chromatography and thin layer chromatography were used to separate a mixture of fluorene and 9-fluorenone. These two methods were then compared, and the results were analyzed. In column chromatography, 0.1010 g of mixture was separated. During the separation, fluorene eluted first. This compound was white in color once dried with the rotary evaporator. A percent yield of 93.47% was calculated for fluorene. The product that eluted first was confirmed to be fluorene by the IR spectrum obtained and the experimental melting point. The IR spectrum RM-02-CC1 was the spectrum obtained for this compound. Aromatic carbon- hydrogen bonds, carbon-carbon double bonds and hydrogens attached to sp2 carbons were shown by peaks 3038
In addition to this, these compounds also display antagonist activity to calcium 23. For this reason, and for their associated pharmacological properties, a lot of interest and attention has been drawn to them in the recent years by researchers 22. A couple of methods have consequently been developed for the preparation of the octahydroquinazolinone derivatives 2. The most common of which include the Biginelli one pot reaction that involves urea/ thiourea, aromatic aldehydes and dimedone 24. Other methods include synthesis with the help of catalysts like concentrated sulfuric acid, Nafion-H, ionic liquid, and TMSCI 24. Synthesis in low ethanol could also be adopted but it is characterized with product yields that are between 19-69% and these are
and Gram-negative bacteria.[139] Mannich reaction also plays a significant role in bioactive skeleton target synthesis. Chernov et al. reported the synthesis of alkaloid-like molecules 22 and 23 from lambertianic acid via Mannich-type intramolecular ring closure reaction (Figure 6).[140]
In 1935, Robert Robinson and his colleague William Sage Rapson published a series of articles for the Journal of the Chemical Society. In them, Robinson and Rapson detail how they performed a number of experiments that synthesized molecules similar in structure to sterols. In particular, Part 7 of their experiments describes what is today known in organic chemistry circles and classrooms alike as the Robinson Annulation Reaction. Figures 1 and 2 above demonstrate two examples of the mechanism for the Robinson Annulation Reaction. In Robinson’s words (1935), this reaction involves a ketone that “might undergo double cyclisation” with formation of a new structure (p. 1533). The Robinson Annulation Reaction constructs a new ring (for example, a six-membered ring) from the original starting ketone found in the reactants. Typically, a structure known as an enolate (the anion formed when an alpha hydrogen in the molecule of an aldehyde or a ketone is removed as a hydrogen ion and contains a double bond because it is resonance stabilized—source: science.uvu.edu) would be added to a methyl vinyl ketone or other enone (compound containing a ketone and an alkene). This process is also known as a base-catalyzed Michael addition. Dehydration, or removal of H2O, then occurs to give a cyclohexenone product.
(±)-morphine. A series of reductive steps were followed after the formation of this intermediate to produce morphine[8].
There are four different types of hydrocarbons each having a different homologous series (formula for carbon chain). These being an alkane (formula = CnH2n+2), alkene (formula = CnH2n), alkyne (formula = CnH2n-2), and an alkanol which has the same formulae as an alkane only that is has a hydroxide molecule which replaces one of the hydrogen atoms (refer to figure 3 and
Product 3 was isolated in a low yield of 27% and with some solvent impurities as shown by the analytical techniques but it was indeed synthesised successfully.
More than 45 million chemical compounds are known and the number may increase in million every year, without cheminformatics, the access of these huge amounts of information is very difficult.
An effective oxidation of the secondary alcohol with chromic acid to produce the corresponding ketone. In this report the synthesis of 4-methyl-2-pentanone from 4-methyl-2-pentanol via an adapted jones oxidation1, using diethyl ether as the solvent and concentrated sulphuric acid, is described. An overall yield of 35.74 % was achieved and the product was characterised by NMR, IR and boiling point analysis.
Organic chemistry is the study of carbon and its compounds (Alcin). Carbon is less than one percent of all matter.Carbon is part of every living thing (Gangson). Carbon makes up eighteen percent of all the matter in living things. (Alcin). The average human body has about 16 kilograms of carbon in some form of this element. Carbon is a part of DNA and proteins. (Robertson).
H. Fischer. Organic Syntheses Coll. 1943, 2, p. 202; H. Fischer. Organic Syntheses Coll. 1935, 15, p. 17.
One of the most important uses of organic compounds is in medicine. All living things have four organic molecules - carbohydrates, proteins, lipids and nucleic acids. Without carbon chains and nucleic acids, DNA would not exist. Enzymes which produce chemica...
Guanine: Pairing in sequence with cytosine, guanine is derived from purine. Purine is an organic compound structured from a pyrimidine ring fused to an imidazole ring (called a pyrimidine-imidazole ring). The base is represented as ‘G’.