Chemical Reaction of Carboxylic Acids Main Contributor: Chen Swee Lun Carboxylic acids consists of a huge and diverse group of organic compounds that contain the carboxyl group (-COOH). The general formulae for carboxylic acid is CnH2n+1COOH. The presence of hydrogen atom in the carboxyl group gives carboxylic acids an acidic property when the acid is dissolved in water. Methanoic acid, ethanoic acid and propanoic acid are some examples of carboxylic acids. Formic acid, acetic acid and propionic acid are the common names for the three examples respectively.
There is also an ornithine transporter that transport ornithine from the cytosol into the matrix of the mitochondria. The rest of the reactions of the urea cycle occur in the cytosol. Second Step: The next step of the urea cycle is catalyzed by argininosuccinate synthetase. This enzyme uses ATP to activate citrulline by forming a citrully-AMP intermediate. In the second half of the argininosuccinate synthetase reaction, the α-amino group of aspartate attacks the imino carbon releasing AMP and producing argininosuccinate.
The next step is nucleophilic attack by the deprotonated cysteine's anionic sulfur on the substrate carbonyl carbon. In this step, a fragment of the substrate is released with an amine terminus, the histidine residue in the protease is restored to its deprotonated form, and a thioester intermediate linking the new carboxy-terminus of the substrate to the cysteine thiol is formed. Therefore, they are also sometimes referred to as thiol proteases. The thioester bond is subsequently hydrolyzed to generate a carboxylic acid moiety on the remaining substrate fragment, while regenerating the free enzyme. 3.Mechanism of threonine protease Threonine proteases use the secondary alcohol of their N-terminal threonine as a nucleophile to perform catalysis.
They can impart localised structural rigidity, confer cytotoxicity by alkylation, or be secondary metabolites . The chemistry of epoxides is dominated by the reactions that involve opening of the strained three-membered heterocyclic ring by nucleophiles. Such reactions yield valuable bifunctional compounds. In nature, epoxide ring opening is catalysed by the phenolic proton of a tyrosine moiety . But in laboratory, the cleavage usually occurs in non-aqueous media in presence of a Lewis acid
During the processing of an ethoxylated compounds, a carcinogenic by product is created called 1,4-dioxane. Many ethoxylated compounds of fatty alcohols are used in detergents,surfactans,emulsifiers, cosmetic and dispersants and commonly contain traces of 1,4-dioxane. This carcinogen has been found in even in supposedly "natural" brands. (Greenwood]., 2009) 2.5 Other applications of ethylene oxide Ethylene oxide is used in the dried fruit industry to stop microbial spoilage in prunes and, presumably, these treatments are also insecticidal. For use as a sterilizing agent, ethylene oxide is available as an aerosol mixed with propellants of the Freon type.
However, a carboxyl group is formed by the attachment of a hydroxyl group to a carbonyl group. This is why the group is known as carboxyl group. Carboxylic acids can be either aliphatic or aromatic on the basis of the group present. If an alkyl group is present (RCOOH) and if an aryl group is present (ArCOOH). The higher members of the aliphatic carboxylic acids, from C12-C18 are known as fatty acids that are found in nature as natural fats or esters of glycerol.
Isatin The 1H-indole-2, 3-dione (Isatin), possesses an indole nucleus with two carbonyl groups; the keto and lactum group at positions C-2 and C-3. Isatin is an orange to red solid and is mostly used for synthesis of heterocyclic compounds . The chemical structure of Isatin is shown in (Figure 1). Figure 1: Structure of 1H-indole-2, 3-dione (Isatin) In nature, isatin is present in plants of the genus Isatis, in Calanthe discolor lindl and in Couroupita guianensis Aubl. It has also been found as a component of the secretion from parotid gland of Bufo frogs; in humans it is a metabolic derivative of adrenaline .
Therefore, they can undergo electrophilic substitution reaction and the attacking species, in this case, will be an electrophile. The +M effect will result in the concentration of electron density at ortho −and para −positions. However, electrophilic substitution reactions with respect to the haloarene reactions are slow in comparison to benzene reactions. This is because the halogen group present in haloarenes are deactivating because of the –I effect. Hence, electrons are withdrawn from the benzene ring.
Therefore, the pigment intensity is an important indicator of the antioxidant activity of Monascus. Monascus pigments have been used widely as traditional food additives in East Asia . Monascus red pigment has also been use in meat products to substitute nitrites . As reported by , the red polyketide pigments of the fungus Monascus are widely used as natural food colorant in Oriental countries. These filamentous fungi were used to make rice wine, soy bean cheese and angkak which are red rice in many Asian countries like Japan and China for centuries
The oil is also apparently used in Chinese medicine as an emetic or purgative, but overdose can cause violent sickness and maybe death (Duke et al., 1983). S. sebiferum may represent an industrial noxious hazard in terms of both pro-inflammatory and tumor-promoting effects. After the seeds have been processed, the remaining cakes are often used as fertilizer/green manure. A black dye can be prepared by boiling leaves of S. sebiferum in alum water. Tallow wood is white and close-grained, suitable for carving and for the manufacturing of blocks in Chinese printing.