The reason why I selected these three compounds Essays

The reason why I selected these three compounds Essays The reason why I selected these three compounds Essay The reason why I selected these three compounds Essay The reason why I selected these three compounds which are azo dyes, aspirin and soap is because: In the aspect of chemistry, they all have different functional groups and molecular shapes associated with different functions. They are all demanded in the modern world commercially. They are easy and an affordable way of making in the college lab with minor hazards. The aims of this unit is to: A clear awareness of a variety of different functional groups and their reactions. A brief understanding of the reaction mechanism involved in each reaction as well as the shape importance of the molecule relating to its use. ; An in depth insight of the organic synthesis as well as the gradual steps involved in making the product, including the issue of equilibrium reactions and predicted yield. ; Familiarize myself with the different apparatus as well as materials used in the organic synthesis, and their limitations with regardless of yield. ; Show good comprehensive knowledge of the commercial importance of organic compounds and the economic imperatives involved in producing such compounds. AZO DYES 1) Introduction There are different types of dyes. A dye is used to impart color to materials of which it becomes the integral part. They give bright, high intensity colors that can even supply a complete rainbow of colors. Azo dyes are highly important commercially as they are used in the textile industry as acid dyes for wool and their affinity for cotton is increased by the number of auxochromes or azo groups. Auxochromes are groups in a dye molecule that influences the color due to the chromophore. They are groups, such as -OH and -NH2, containing lone pairs of electrons that can be delocalized along with the delocalized electron An azo group is a -N=N- group that is a chromophore (A chemical group capable of selective light absorption resulting in the coloration of certain organic compounds.) Azo dyes are also used as pigments and in color photography. In the UK, companies like James Robinsons Limited make about thirty thousand tones of azo dyes each year. 2) Commercial And Laboratory Synthesis The synthesis of azo dyes involves the reaction of diazotation and coupling and at the end of the reaction, separation of the azo dye from the mixture that is going to be produced. 1) Diazotisation This is the reaction in which produces diazonium salt as well as a -N diazonium ion. This is very unstable when it exceeds temperatures above 10à ¯Ã‚ ¿Ã‚ ½C. Otherwise the -N decomposes into nitrogen gas. 2) Coupling This is the electrophilic substitution on the phenol which produces an energetically stable azo dye. The azo group is -N=N- First step: Diazotisation reaction HNO + HCL + 2H O Phenylamine + nitrous acid + hydrochloric acid phenyldiazonium chloride + water (Diazonium salt) The reaction takes place under 10à ¯Ã‚ ¿Ã‚ ½C to prevent the NN, the N2 diazonium ion decomposing into N2 gas. This suggests that the delocalization of the diazonium ion bond electrons over the benzene ring is only able to stabilize the diazonium salt at cold temperatures. At higher temperatures above 10à ¯Ã‚ ¿Ã‚ ½C, there is too much so therefore the diazonium ion gives way to nitrogen gas. Below shows the reaction mechanism of for the formation of diazonium salt. Now that there is a N2+ diazonium ion, there is now a suitable electrophile to attack a phenol ring. Second Step: Coupling This is where phenol attacks benzene at the 4th position of the ring. The equation for this Is: Phenyldiazonium ion + phenol 4-hydroxyphenylazobenzene + hydrogen ion Azo dyes are very stabilized which is a result of broad delocalization of the electrons through the -N=N azo group (nitrogen double bond). Delocalisation is simply increased stability 3) Relationship Structure/ Function Of Azo dyes The structure of an azo dye is very closely linked to its function as a dye, in terms of color and fastness. Auxochromes can modify the color of a chromophore. The azo functional group itself is also important as this is what part of the light the spectrum absorbs. In the aspect of the fastness, azo dyes are very stable as a result of their chemical structure and they can also be made more color fast by alkylation of phenolic groups ASPIRIN 1) Introduction Aspirin is one of the commonly used pain relief tablets on the world. It is an analgesic, anti-inflammatory, antipyretic inhibitor of platelet aggregation. Aspirin inhibits the enzyme that converts fatty acids in cell membranes into prostaglandin precursors known as endoperoxides. These endoperoxides can be converted into various prostaglandins, including those that produce pain, fever, and inflammation. Generally, one or two 5-grain doses of aspirin can block the prostaglandin formation. The main side effect of aspirin is the tendency of irritation of the stomach lining which causes small amounts of blood loss. In order to prevent this, aspirin is thus buffered and combined with other medicines to produce some desired effect of reducing blood loss. 2) Commercial Synthesis The starting raw materials of the commercial aspirin reaction are: Phenol C6 H3 OH ( l ) Sodium Hydroxide NaOH (aq) Carbon dioxide CO2 ( g ) Acetic Anhydride CH3COOCOCH3 ( l ) Acid H+ (aq) Below are four different stages in which aspirin is made: The next step of this reaction is classified as an esterification reaction. Esterification is simply where an alcohol (the -OH group from salicylic acid) reacts with an acid (acetic anhydride) to form an ester acetylsalicylic acid (ASA). The rates of the esterification reaction are increased by the addition of small quantities of mineral acids such as phosphoric acid (a catalyst) and some heat. http://aspirin-foundation.com/reaction.htm C9H8O4 is the molecular formula for aspirin and this tells you how many atoms are in each molecule of acetylsalicylic acid. So there are 9 C (carbon) atoms, 8 H (hydrogen) atoms, and 4O (oxygen) atoms. Acetylsalicylic acid has two functional groups, the carboxylic acid group COOH and the MeCOOR ester group-(R is used as an abbreviation for an unspecified aliphatic or aromatic chain). The Reaction Mechanism The following diagram shows the reaction mechanism of the aspirin reaction. Note: The sign means it is an equilibrium reaction (a state of balance between two opposing elements). http://tooldoc.wncc.neveda.edu/aspirin.htm There are H+ ions because they have been catalyzed by a mineral acid The H+ (proton) from the acid attacks the carboxyl oxygen in the C=O. This therefore pushes two of the oxygen electrons in one of the bonds down that is the electrons are delocalized and spread out between the two oxygen atoms. In proximity of these electrons, the O-H bond with the oxygen in the alcohol breaks and this then rearranges the electrons to form a temporary bond between the two reactants (oxygen and alcohol). The alcoholic oxygen atom has now got a temporary positive charge as it now has three bonds to it in the intermediate at step 2 of the reaction mechanism. The oxygen loses its H+ which is then attracted to one of the lone pairs on the other oxygen to make it miserable and positively charged with three bonds. The H-O-H sort of water molecule in step 3 detaches itself to form a delocalized electron system. This delocalized electron system gives the molecule adequate stability when the H leaves forming an H+ ion. This H+ ion (proton) added in the step 1 is the original acid catalyst used at the beginning of the reaction. A catalyst is basically substance that increases or decreases the rate of chemical reaction between the other chemical species without being consumed up in the process. Laboratory Synthesis The starting materials of the laboratory synthesis of aspirin are salicylic acid and acetic anhydride both of which are easily available and inexpensive. Acetic anhydride reacts with the phenolic hydroxyl group of the salicylic acid to produce acetylsalicylic acid (aspirin) and acetic acid. Acetylsalicylic acid has two functional groups, the carboxylic group COOH and the MeCOOR ester group-(R is used as an abbreviation for an unspecified aliphatic or aromatic chain). The rates of esterification are increased by the addition of small quantities mineral acids such as phosphoric acid (a catalyst) and some heat. Below is an equation that shows this: 3) Relationship structure/function Understanding the similarities between the two different molecules (aspirin and paracetamol) which achieve similar effects can be a profitable way of having a clear distinction of the molecules. Below are two pictures showing the structure of aspirin compared to paracetamol: Aspirin Paracetamol The structure of aspirin is related to its shape, although the presence of the functional group is also important. As seen above, all two have a six membered ring structure, which tends to avoid the polar environment of water and a comparatively small appended group of atoms and are able to bond to part of their receptor molecule. The similarity in the structure of these molecules is clearly obvious and from their similar pain killing actions so therefore, we can assume that they both can fit into similar active sites even before the details of their active sites have actually been determined. SOAP 1) Introduction The term soap is a class name for the sodium and potassium salts of stearic acid, C17H35 COOH, and other fatty acids. Soaps are and have been there for centuries, made by the addition of hot concentrated aqueous sodium hydroxide solutions to fats such as glyceryl stearate. In the world every year, about 500,000,000 soaps are produced. Generally, soaps are used for bathing and washing clothes. It works by lowering the surface tension of water, by softening grease, and by absorbing dirt into the foam. Soaps come in three different states: which are the powder, liquid and bar forms. Some liquid soaps are very thick as well as sticky so they are called gels. The first step in manufacturing all the three forms of soap is the right selection of the raw materials as well as considering that if they can react accordingly with other ingredients and are also safe for humans if accidentally consumed. Also environmental safety is considered as precaution. 2) Synthesis In laboratory synthesis, the sodium and potassium salts of fatty acids, from which soaps are prepared, consist essentially of the glycerol esters of these acids. In soap manufacture or commercial synthesis, the oil or fat is heated with dilute aqueous sodium hydroxide or potassium hydroxide in large vats. When hydrolysis is complete, the soap is salted out which is then treated with different fragrances . Transparent soap is manufactured from decolorized fats and liquid green soaps from potassium hydroxide. Commercial synthesis Soap involves a two step synthesis: First Step: Esterification This is the process whereby an alcohol is reacted (functional group -OH) and a long chain of carboxylic acid (functional group -COOH) to make an ester (functional group -C-O-O-C-). The long chain carboxylic acid is issued from fats and oils which is called a fatty acid. For soap, the alcohol is glycerol (propane-1,2,3-triol) and the carboxylic acid used to make soap is oleic acid (octadeca-cis-enoic acid) as well as stearic acid (octadecanoic acid). Oleic acid is best derived from olive oil or virgin olive oil containing up to 5g of oleic acid per 100g. Stearic acid is best derived from animal fats. Glycerol is a molecule with three -OH groups, therefore three molecules of carboxylic acid can couple to glycerol to make an ester. The ester will therefore be a backbone of glycerol with three side chains in which each is a potentially different fatty acid. Below is a picture of 1 molecule of glycerol + 3 molecules of a carboxylic acid = a triglyceride: There are therefore 3 ester linkages in a triglyceride. An ester linkage links an alcohol and a carboxylic acid. Below is a picture that shows this: Note that the R group is a general organic group but what is much more interested in is the functional group that makes the type of chemical needed. Example, below is diagram of CH3COOH (ethanoic acid) and CH3CH2OH ethanol which forms an ester of CH3COOCH2 CH3 + H2O A water molecule is released for every ester linkage formed. Therefore esterification is also a hydration process. Because there is a tri-glyceride and three ester linkages in the making of soap, this shows that three water molecules will be released in the reaction. The Reaction Mechanism In this reaction, a mineral acid is needed to act as a catalyst for the reaction to lower its activation energy. This acid is combined with the carboxylic acid and helps the alcohol react with it. The acid is released unchanged at the end of the reaction. Heat is also applied in this reaction process. The reaction mechanism is called The mechanism of Fischer The following pictures below shows some of the fatty acids used to make soap: Below is a picture of triglycerides of stearic acid which have three chains of fatty acids for each glycerol molecule. Before the reaction of the carboxylic groups and fatty acids, they had a -COOH group which reacted with the -OH on the alcohol. The -COOH loosed its OH and the -OH loosed its H. OH+H=H2O. The three molecules of H2O are released to form the ester as seen in the picture above. Below is another fat and another diagram of a triglyceride that has three tails. Each tails forms a different fatty acid. http://members.aol.com/jitsm/sas/Lowry_Paper/triglyceride3.gif Second Step: Hydrolysis = Saponification A hydrolysis reaction is the decomposition of a chemical compound that is reacted with water or the -OH group which breaks up a molecule. In this reaction step, glycerol is removed from the ester whiles at the same time, each of the fatty acids are turned into a sodium or potassium salt. The ester is heated under reflux with NAOH(aq) (sodium hydroxide) (or KOH (aq) for potassium hydroxide). The equation below shows the saponification of a triglyceride of stearic acid soap= sodium stearate. In the formula of the salt above, instead of : CH3CH2CH2CH2CH2CH2CH2CH2CH2CH2CH2CH2CH2CH2CH2CH2CH2COO-NA There is CH3(CH2)16COO-Na+ Third Step: Precipitation = Salting Out In this step, surplus amounts of saturated sodium chloride solution are added to the mixture obtained above to get a precipitate of soap. 3) Relationship Structure/Function: Soap is bubbly and works because it has a hydrophilic end and a hydrophobic end. The hydrophilic end means having a strong affinity or attraction to water and the hydrophobic end means having a strong aversion for water. Soap is a surface active material as this chemical agent is capable of quick reaction activity. THE MAKING OF SOAP IN COLLEGE LABORATORY: PRACTICAL WRITE-UP Before the experiment starts, the will be some safety precautions considered such as: the wearing of splash proof chemical goggles in case hot oil splashes over and catches fire and also including lab coats worn to prevent any corrosive substances falling on clothes of students in the laboratory. Materials Needed First Step Synthesis Separation After First Step Second Step Of Synthesis Collection Of Final Product Glycerol Oleic acid Concentrated sulphuric acid in fume cupboard (corrosive) Anti-bumping granules Measuring cylinder (x2 Pear-shaped flask Reflux condenser Bunsen burner Beaker Separating funnel Conical flask Digital weighing scale Aqueous sodium hydroxide conc. 3M (caustic) Measuring cylinder Bunsen Burner Saturated aqueous sodium chloride Digital weighing scale Filter funnel Filter paper Beaker Labels First Step Of Synthesis: Esterification 1mol glycerol + 3mol oleic acid 1mol glycerol trioleate + 3 mol water The reflux apparatus was set up as seen above in the synthesis of soap (Hydrolysis) and the water was kept in mind to be kept on . Now with the measuring cylinder, 10.0cm3 of oleic acid was measured and carefully poured it into the pear-shaped flask. After this, 5.0cm3 of glycerol was accurately measured using the additional measuring cylinder available and then also added to the pear-shaped flask. In the fume cupboard, 3-5 drops of the concentrated sulphuric acid mixture was added to the pear-shaped glass. Also a pinch of anti-bumping granules was added in the pear-shaped flask to stop any bubbles from forming and splashing the reactants everywhere. After this, the pear-shaped flask was clipped securely in the reflux apparatus for it to reflux for about half an hour as well as remembering not to overheat the mixture or let it dry out. After refluxing, two separate layers of liquid were produced. Separation Following First Step The two liquid layers was separated using the separating funnel after the esterification process. The lower layer of the two liquids were collected in a beaker and discarded off whiles the remaining top dark layer which is the ester was put in a pre-weighed conical flask which was heat resistant. Below is a table of the weighed product: Weight of conical flask (g) 89.84 grams Weight of conical flask+ ester (g) 97.16 grams Weight of ester (g) 7.32 grams Second Step Of Synthesis: Hydrolysis 1mol glycerol trioleate + 3 mol aqueous sodium hydroxide 1mol glycerol +3 mol sodium oleate Caution: The Sodium hydroxide was highly concentrated, so care was taken. Now with a measuring cylinder, 20.0cm3 of aqueous sodium hydroxide (3M concentration) was accurately measured and put into the heat resistant conical flask which had the ester in. This started to create a precipitate. The mixture was carefully heated up by the Bunsen burner to simmer it and also, with cautions of not boiling over for about ten minutes. After the tenth minute the bunsen burner was turned off and the mixture was allowed to cool down. Collection Of the Final Product (Soap) Following hydrolysis, some amounts of the soap was already precipitated but some was still in the solution. Using the saturated sodium chloride, the soap was precipitated in the solution. This was started by using 10cm3 of saturated sodium chloride, swirling the flask gently. The precipitate (soap) was allowed to settle for a few minutes and then filtered in the filter funnel using the filter paper to separate the solid and liquid was collected in a beaker. The solid soap was left in the filter to continue filtering which took quite a bit of time. The liquid collected in the beaker was discarded and a preliminary weight measurement of the soap was taken. The mixture was allowed to dry out naturally and in a few days time, the final weight of the soap was accurately taken and recorded as the final mass of soap obtained. Calculations Mass Of soap obtained (g) 7.28 grams Molar mass (g mol-1) (Sodium Oleate) 304 gram/mol-1 Number of moles of soap obtained (mol) 7.28à ¯Ã‚ ¿Ã‚ ½304=0.2023 Number of moles of soap theoretically obtained from stoichiometry (mol) Mol Of ester 7.32 M. mass of oleic acid 884 =8.2805à ¯Ã‚ ¿Ã‚ ½10-3 à ¯Ã‚ ¿Ã‚ ½ 3 = 0.2024 mols Percentage Yield Mass Obtained 7.28 Theo. Mass 8.2805 =0.879à ¯Ã‚ ¿Ã‚ ½100= 87.9% The % yield was a bit high may be because there wee some impurities in it. Testing The Soap In testing the soap, a little portion was broken from it after calculating the percentage yields and other calculations and then was put in a test tube. Water was then put in it to see if it would react with it and produce foam which it did.