Friday, March 29, 2019

Laboratory Report on Aldehydes and Ketones

Laboratory Report on Aldehydes and KetonesMark Norly L. TundagI. OBJECTIVESAt the give the axe of the experimentation, the students are able to identify the functional chemical gathering present in aldehydes and ketones, also on determining their physical and chemical properties and to perform chemical test to distinguish one from the other.II. MATERIAL and APPARATUSThe experiment utilise a bunsen burner, ampules, 100 ml beaker, test tube holder, vial brush, clay flame shield, wire gauze, ethanal1, benzaldehyde2, acetone3, 2,4-dinitrophenylhydrozine4, ammoniacal silver nitrate tooth root (Ag((NH)3)2)NO3, Fehlings a and b, 6m sulfuric acid H2SO4, very dilute potassium permanganate KMnO4, distilled piss H2O and Schiffs reagent5.III. PROCEDURE and OBSERVATIONSThe test for the physical characteristics of the coulombylic compounds namely the acetaldehyde (an acyclic aldehyde), the benzaldehyde (an aromatic aldehyde), and acetone (a ketone) was the first to be investigated. Fo ur drops of distributively of the carbon paperyl compounds were mixed with 2 ml of pee in triple interrupt vials. Only the aromatic aldehyde did not form a equivalent mixture it formed two layers instead, wherein benzaldehyde at settled at the bottom.B1.The answer between the carbonyl compounds and the 2,4-dinitrophenylhydrozine was performed and the set up was identified. After taking five-spot drops from eliminately of the carbonyl compounds that were placed again in tercet separate vials, yellow-orange effectuate that readily formed was seen after adding into each of the vials other 5 drops of the 2,4-dinitrophenylhydrozine.2. The chemical fight backion of the carbonyl compounds with the Tollens reagent was performed next. Only with the aldehydes did a silver mirror on the sides of the vials were observed to exist when the carbonyl compounds mixed with Tollens reagent in three separate vials were heated for ten minutes. A black stain was but seen on the ketone vi al with the reagent.3. The result of the carbonyl compounds with the Fehlings test was determined. From blue, the only(prenominal) compound that changed its color to green was the aliphatic aldehyde when the mixture of five drops of fehlings a and b with five drops of each of the carbonyl compounds in three separate vials were placed on the water bath. The remaining carbonyl compounds had no patent changes happened.4. The reaction of potassium permanganate to the carbonyl compounds was observed and the organic products identified. Brown precipitate was formed on both(prenominal) the aliphatic and aromatic aldehyde but not on the ketone, when five drops of the carbonyl compounds was added to the mixture of the five drops pink sinister potassium permanganate acidified with 2 drops of 6M sulfuric acid placed into three unalike vials.5. The result of the Schiffs test with the carbonyl compounds was described and interpreted. Only the aldehydes were a changed of color occur vehement when five drops of the Schiffs reagent was placed in the three separate vials containing the carbonyl compounds. From cloudy white solution of acetaldehyde to lilac and yellow solution of benzaldehyde to a colorless solution with pinkish globule that settled at the bottom of the vial.IV. CONCLUSIONAldehydes and Ketones are collectively called as carbonyl compounds, referring to their carbonyl C=O functional group that affects their solubility rendering it comparatively higher because of the molecules mogul to heat content bond with water but it is also dependent to the molecular mass and the number of carbon present on the nonpolar R group, if the R group is ironlike enough to mucklecel out the hydrogen bonding of the functional group with water it will make the entire compound insoluble. Benzaldehyde, for example is insoluble because of the presence of the benzene ring that is nonpolar in nature.To investigate the chemical properties of carbonyl compounds and to differentia te one from the other some reagents were utilize in the experiment 2,4-dinitrophenylhydrozine for example gives off a yellow orange precipitate when it detects the presence of the carbonyl functional group in a solution, the aliphatic aldehyde reacted to the reagent forming acetaldehyde-2,4-dinitrophenylhydrozone1, the aromatic aldehyde reacted to the reagent forming benzaldehyde-2,4-dinitrophenylhydrozone2, the ketone reacted to the reagent forming acetone-2,4-dinitrophenylhydrozone3. Tollens that contain ammoniacal silver nitrate on the other hand, differentiates aldehyde from a ketone considering the fact that silver mirror on both the vials were formed due to the reduction of the oxidizing agent forming Ag+, only aldehydes skunk undergo oxidization because of the presence of an oxidizable hydrogen on their expression in which case ketones dont look at. The resulting organic product of the oxidation of aldehydes is carboxylic acid. This result can also be duplicated using an other oxidizing agent that is KMnO4 in an acidic medium giving off brick red precipitate (the oxidizing agent that is reduced) and the corresponding carboxylic acid, obviously still in this reaction at that place will be no change to be expected with the ketone. The strength of the oxidizing agents can also have a great impact to an impending reaction because if a weak oxidizing agent is used only the aliphatic aldehyde can react, this is evidently observed in the experiment using the Fehlings test. The reagents contain copper sulfate in five moles of water with two drops of sulfuric acid and potassium tartrate sodium hydroxide that allowed the formation of the carboxylic acid CH3COOH and the precipitate that is brick red, the Cu2O. Although, the stated reactions above can be handful enough evidence to differ an aldehyde and a ketone there is also the Schiffs test to add the list, the ketone wont still react and the change in color is still on the side of the aldehydes , this ran ges from lavender to pink. The more I have journeyed through these experiments, the more I came to be amaze with the organic compounds I once just often give less attention to other than the comfort room while culture the labels and ingredients at the back of the shampoos and soaps and conditioners I used. Chemistry, my first love.V. THEORITICAL BACKGROUNDAn aldehyde contains at least(prenominal) one hydrogen disposed to the C of a C=O (carbonyl group). A ketone contains two alkyl groups attached to the C of the carbonyl group. The carbon in the carbonyl is sp2 hybridized, has a bond angle of 120o, and is trigonal planar. Aldehydes and ketones have dipole-dipole attractions between molecules, and no hydrogen bonding between molecules. These compounds can hydrogen bond with compounds have O-H or N-H bonds. The melting points and boiling points of aldehydes and ketones are between alkanes and alcohols.The slightly positive carbon atom in the carbonyl group can be attacked by nucle ophiles. A nucleophile is a negatively aerated ion (for example, a cyanide ion, CN), or a slightly negatively charged part of a molecule (for example, the lone pair on a nitrogen atom in ammonia, NH3). During a reaction, the carbon-oxygen double bond gets broken. The wage effect of all this is that the carbonyl group undergoes addition reactions, often followed by the loss of a water molecule. This gives a reaction known as addition-elimination or condensation. An aldehyde differs from a ketone by having a hydrogen atom attached to the carbonyl group. This makes the aldehydes very easy to oxidize. For example, ethanal, CH3CHO, is very easily oxidized to all ethanoic acid, CH3COOH, or ethanoate ions, CH3COO-. Ketones dont have that hydrogen atom and are repellent to oxidation. They are only oxidized by powerful oxidizing agents which have the ability to break carbon-carbon bonds.REFERENCEStroker, Stephen H., Exploring General, Organic, and Biological Chemistry, Cenage Learning, 2 010

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