Introduction
Methyl butyrate or methyl ester of butyric acid is an ester with a fruity odor of pineapple, apple and strawberry. Present in small amounts in several plant products, especially pineapple flavor is produced by distillation from essential oils of vegetable origin. This ester is also manufactured on a small scale for use in perfumes or food flavors. Esters, in general, can be defined as the reaction products of carboxylic acids and organic alcohols. Chemically, an ester is the condensation product that results when a carboxylic acid is reacted with an alcohol1. Esterification of carboxylic acids with alcohols represents a well-known category of liquid-phase reactions of considerable industrial interest due to enormous practical importance of organic ester products. Esters are important fine chemicals used widely in the manufacturing of flavors, pharmaceuticals, plasticizers, solvents of paints, adhesives, pesticides, polymerization monomers and in the preparation of biodiesel from lower quality feedstock. Derivatives of some esters are useful as chemical intermediates and monomers for resins and high molecular weight polymers. They are also used as emulsifiers in the food and cosmetic industries2, 3.
Many routes are available for organic esters synthesis. The traditional route for preparing esters is via reaction of the carboxylic acid with an alcohol using homogeneous catalysts such as sulfuric acid or para-toluene-sulfonic acid4,5,6. Esterification can take place without adding catalysts due to weak acidity of carboxylic acids themselves. However, the reaction is extremely slow and requires long time to reach equilibrium at typical reaction conditions7. A common method of operating equilibrium limited reactions is to...
... middle of paper ...
...terification with methanol increases with an increase in temperature over the range of study (323-343 K); passes through maximum with increasing alcohol to acid ratio (1-4); increases with the increase in catalyst loading(0-8.5 % w/w). Conversion was optimum for the stirrer speed of 300 rpm indicating the absence of film diffusion. The conversion of butyric acid was dropped in the presence of added water due to inhibiting effect of water. The maximum conversion of 94.5 % was observed at optimum reaction conditions. Thus, the ion exchange catalyst was found to be very effective for the methyl butyrate synthesis. The Langmuir-Hinshelwood-Hougen-Watson Dual Site (considering reactants and products adsorbed on catalyst surface) heterogeneous model could be successfully applied for representing esterification kinetics for the reaction between butyric acid and methanol.
Step 6: The ethyl ester on (20) is hydrolysed using concentrated sulphuric acid in a refluxing 1:1 acetic acid/water mixture.
The experimental Fischer esterification of 8.92g of acetic acid with 5.0g of isopentyl alcohol using concentrated sulfuric acid as a catalyst yielded 4.83g (65.3% yield) of isopentyl acetate. The product being isopentyl acetate was confirmed when the boiling point during distillation had similar characteristics to that of the literature boiling points2. Physical characteristics like color and smell also concluded a match of our product with what was intended. 1H-NMR spectroscopy analysis supported this claim due to the fact that the integration values and chemical shifts were comparable to isopentyl acetate. Lastly, infrared spectroscopy (IR) showed similar key characteristics of our product’s wavelengths to that of pure isopentyl acetate5.
Esters are defined as molecules consisting of a carbonyl group which is adjacent to an ether linkage. They are polar molecules which are less polar than alcohols but more so than ethers, due to their degree of hydrogen bonding ability. Most often derived from reacting an alcohol with a carboxylic acid, esters are a unique, ubiquitous class of compounds with many useful applications in both natural and industrial processes 1. For example, within mammals, esters are used in triglycerides and other lipids as they are the main functional group attacking fatty acids to the glycerol chain 2. A unique property of esters is their tendency to give off distinct aromas such as the scent of apples (Ethyl caprylate) and bananas (Isoamyl acetate). This is of a unique importance especially in industries that utilize flavors and aromas such as the tobacco, candy and alcohol industry. Consistent research is conducted in order to enhance and increase the effectiveness of esters in these products 3.
barbier reaction: In a 50 mL round bottom flask that had a reflux condenser attachment, saturated ammonium chloride (5 mL), THF (1 mL), zinc powder (0.4 g), benzaldehyde (0.500 mL, 0.5225 g, 4.92 mmol), and allyl bromide (0.470 mL, 0.6533 g, 5.40 mmol) were charged with stir bar and stirred at room temperature for 45 minutes. Diethyl ether (10 mL) was added to the reaction mixture and stirred. The mixture was gravity filtered into a beaker that was topped with a watchglass. The filtrate was transferred to a separatory funnel and the organic layer was extracted with deionized water (10 mL) and diethyl ether (15 mL). The organic layer was placed into an Erlenmeyer flask and the aqueous layer was placed into a beaker, which was extracted with
Another simple improvement to the experiment could have been the addition of time to procedure A as well as possibly increasing the time heated under reflux. Since the entire procedure B had to be completed before the period of reflux was done, some of the steps and processes involved in procedure B were rushed or not given the adequate time allowed to produce the best sample of product. In general, the laboratory experiment was successful and turned out well to find that the bromide ion was the better nucleophile to both the n-butyl alcohol as well slightly toward the t-pentyl alcohol used in the
ester, and we produce the most acid and alcohol. In bottle 3 we still have a good
As a final point, the unknown secondary alcohol α-methyl-2-naphthalenemethanol had the R-configuration since it reacted the fastest with S-HBTM and much slower with R-HBTM. TLC was a qualitative method and ImageJ served as a quantitative method for determining which reaction was the faster esterification. Finally, 1H NMR assisted in identifying the unknown from a finite list of possible alcohols by labeling the hydrogens to the corresponding peaks.
Fischer Esterification is a unique type of esterification first discovered by Emil Fischer and A Speier in 1895. Fischer Esterification is a mechanism of which an ester is formed as a product when a carboxylic acid is treated with an alcohol and an acid catalyst. Together with ester, water is also liberated on this reaction. The key bonds formed in this reaction is C-OR, of which the oxygen bonded to carbon is the oxygen from the alcohol, not the oxygen originally bonded to it from the starting carboxylic acid. The key bonds broken is C-OH, the oxygen from the carboxylic acid bonds with the hydrogens that will then form water. So, the reaction does not simply just break the H and the R but rather -OH and -OR. This reaction is an equilibrium reaction. Applying Le Chatelier’s principle, if alcohol is used as a solvent to carboxylic acid and have a small amount of water (product), then the reaction would favor the product. On the other hand, if the reaction is to go backwards, whereas the reaction would start from an ester going to a carboxylic acid, then the water would be used as a solvent. Common acid catalyst are sulfuric acid, tosylic acid, and Lewis acids such that of scandium(III) triflate. Tertiary alcohols are prone to elimination whereas phenols
The purpose of conducting this experiment was to synthesise and characterise for the preparation of benzocaine via a fishcer esterification reaction by the means of amino benzoic acid alongside ethanol. The product was also precipitated from a solution in order to gain a pH of 8.The secondary aim was to esterify the reaction in an equilibrium reaction catalysed via the addition of acid shown below:
Many derivatives and oleochemicals of castor oil require relatively simple methods for their production, while higher generation derivatives such as sebacic acid or salts of ricinoleic and undecylenic acid could require more sophisticated production methods.
Reacting 1-butanol produced 2-trans-butene as the major product. 1-butanol produces three different products instead of the predicted one because of carbocation rearrangement. Because of the presence of a strong acid this reaction will undergo E1 Saytzeff, which produces the more substituted
A number of EU members have implemented environmental tax reforms (ETRs) which are defined as a reform of the national tax system that shift the tax burden from taxation of labor to taxation of carbon-energy, and the reforms were first introduced in Scandinavian countries since 1990 and then applied in other European countries, such as, Germany and Britain (PTAK, 2010; COMETR, 2007). This project summarizes an assessment of the German ETR and its effect on technological innovation by trying to answer the research question: Did the German ETR increase technological innovation? The question is motivated by general environmental considerations, for instance, slowing down the global warming by reducing energy consumptions and carbon emissions. My paper’s aim is to assess the effect of the German ERTs on technology innovation level specifically, and this is motivated by the following relevant facts. The German ETR was launched in April 1999, and it has been adopted in Germany for more than ten years; thus, there are plenty of available data for us to assess the impacts of this ETR regarding to German government’s motivations. This ETR was proposed because the German government wanted to increase technology innovation, to create additional jobs, and to decrease energy consumption (Agnolucci, 2009; Beuermann and Santarius, 2006). Moreover, it is important for us to assess the impacts of ETRs from different angles, for example, the level of technology innovation, rather than assessing the impacts on the level of energy consumption and employment that abundant papers have discussed. The rest of the paper is organized as follows. Section 2 presents a literature review of the related literature ...
Emulsions are important in food science. Not only do they provide an important sensory aspect in many foods, but a functional one as well. From hollandaise to ice cream, getting hydrophobic and hydrophilic molecules to play nice with each other can be a difficult task. According to Modern Cuisine, it was previously thought that Hollandaise, a classic French emulsion of egg and butter, could only be made by letting butter drip from natural heat of the hand. Of course, modern science has taught us that, with the use of emulsifiers, these mystic mixtures can be created without the voodoo and magic once thought necessary. This paper will discuss emulsions as applied to hollandaise, chocolate, hot dogs and their characteristic pH, moisture content, shelf stability and quality of viscosity. An explanation of the chemical processes that occur between the raw ingredients of each food and the relationship between the structure and function of their components will be explained, as well as the importance of the chemical changes that take place during production. The characteristics that define these foods as emulsions will be compared and contrasted to further elucidate the mystery of the emulsion. Bon Appetite!
Predictions may be made about the suitability of possible catalysts by assuming that the mechanism of catalysis consists of two stages, either of which can be first:
The solution for the resistance to oxidation of p-toluic acid was solved by the discovery of bromide-controlled air oxidation in 1955 that was led to the implementation of AMOCO process [28-31]. In AMOCO process, the oxidation of para-xylene was conducted using a combination of three ions as a homogeneous catalyst which is cobalt, manganese and bromide ions. Acetic acid and oxygen/air were used as solvent and oxidant, respectively [32]. The common bromide ion sources are hydrobromic acid (HBr) and sodium bromide (NaBr). The oxidation operated at 175-225°C and 15-30 bar of oxygen. The terephthalic acid formed mostly in the form of solid due to the low solubility of terephthalic acid in the acetic acid. AMOCO process successfully gives a promising reaction yield, since more than 98% of para-xylene reacted, while terephthalic acid selectivity yield was about 95% in the reaction time of 8-24 hours (Scheme 3).