Free Essay

Aldol Condensation

In: Science

Submitted By mishv212
Words 2021
Pages 9
An Aldol Condensation Reaction: The Synthesis of Tetraphenylcyclopentadienone—An
Example of a Double-Crossed Aldol

Addition Reactions of Carbonyl Groups

The chemical reactivity of aldehydes and ketones is closely associated with the presence of the carbonyl group in their structures. For example, both aldehydes and ketones undergo addition reactions such as the addition of a Grignard reagent to the carbonyl group as shown in Figure 1.

Figure 1. Addition reactions.

The reactions in Figure 1 differ only because the pink H of an aldehyde is replaced by R′′ in the ketone. The addition reaction occurs at the carbonyl group. The carbonyl group is polarized so that the carbon atom bears a partial positive charge and the oxygen atom bears a partial negative charge. The R′ group of the Grignard reagent is negative relative to the positive Mg atom. Thus, the negative R′ group bonds to the positive carbon atom, and the negative oxygen and metallic magnesium form an ionic bond, yielding a salt in each reaction. The addition product is acidified in each case to make a covalent alcohol. The aldehyde produces a IIo alcohol; whereas, the ketone produces a IIIo alcohol owing to the R′′ group.

The two equations for addition reactions in Figure 1 are summarized in Figure 2. A nucleophile (negative species) bonds to the carbonyl carbon (positive), breaking the π bond of the carbonyl group. Figure 2. Addition of a nucleophile to a carbonyl group.

Figure 2 focuses our attention on the salient part of an addition reaction that involves either a ketone or an aldehyde. A nucleophile bonds to the carbonyl carbon. In an aldol addition reaction, the nucleophile is an enolate formed from an aldehyde or ketone by the removal of a hydrogen atom next to the carbonyl group. The enolate (negative nucleophile) then adds to a carbonyl group of another aldehyde or ketone as shown in Figure 1.

Formation of an Enolate from an Aldehyde or Ketone

Aldehydes and ketones that possess alpha hydrogen atoms can form enolates. The Greek alphabet (α, β, γ, etc.) is used by chemists to identify carbon atoms in relation to the carbon atom of a carbonyl group. An alpha carbon atom is a carbon atom that is bonded directly to the carbon atom of a carbonyl group. A beta carbon atom is the second carbon atom from the carbonyl carbon, a gamma carbon is the third carbon away from the carbonyl, etc. Likewise, hydrogen atoms are named according to the name of the carbon atom to which they are bonded. A hydrogen atom bonded to an alpha carbon is called an alpha hydrogen, etc. Figure 3 shows these relationships for acetaldehyde and 2-pentanone.

Figure 3. Alpha hydrogens.

Alpha hydrogen atoms are important because they can be removed by a base. Thus, the hydrogen atoms shown in blue and pink in Figure 3 can be removed in base. What is the first thing that happens when acetaldehyde is placed in base? The base removes or abstracts a hydrogen atom. The base forms a new bond with a pair of electrons from the base, so the hydrogen atom leaves its electrons with the alpha carbon atom. Thus, the base abstracts H+ or a proton, leaving C- or a carbanion. Compounds that contain only one kind of equivalent alpha hydrogens (e.g., acetaldehyde has 3 equivalent blue H atoms) are preferred over compounds that contain two kinds of equivalent alpha hydrogens (e.g., 2-pentanone has 2 pink and 3 blue equivalent H atoms). Figure 4 shows the first step when acetaldehyde reacts with hydroxide ion, which may come from sodium hydroxide or potassium hydroxide.

Figure 4. Formation of carbanion.

A base abstracts an alpha hydrogen atom to form a carbanion. The carbanion is a nucleophile, which can react with a carbonyl group as shown in Figure 2. The carbanion shown in Figure 4 is also an enolate because of resonance. Figure 5 shows how the initially formed carbanion from acetaldehyde is resonance stabilized via the enolate. Thus, alpha hydrogen atoms are acidic because the resulting anion is resonance stabilized.

Figure 5. Resonance structures of carbanion and enolate.

Self-Aldol Addition Reaction

The carbanion or enolate of Figure 5 is a nucleophile, which can add to a carbonyl group of an aldehyde or ketone. When an enolate made from an aldehyde such as acetaldehyde reacts with another molecule of acetaldehyde, the addition product is a dimer and the reaction is called a self-aldol addition reaction. Figure 6 shows the carbanion (enolate) of Figure 5 adding to a second molecule of acetaldehyde.

Figure 6. Synthesis of aldol.

Steps 1-3 of figures 4 and 6 show the complete mechanism of an aldol addition reaction. In Step 1, base abstracts an alpha hydrogen to make an enolate. In Step 2, the enolate adds to the carbonyl of a second molecule, forming an oxyanion, which abstracts a proton from water to make 3-hydroxybutanal. The hydrogen atom that is abstracted in Step 3 replaces the H atom that was abstracted in Step 1, so the product is a dimer of the starting compound. 3-Hydroxybutanal is the first member of a family of compounds called aldols. Aldols are so named because they contain an aldehyde and an alcohol, and the alcohol hydroxyl group is bonded to a carbon atom that is two carbon atoms away from the carbonyl carbon atom. The structural feature in an aldol is a β-hydroxycarbonyl. Any aldehyde or ketone with a β-hydroxyl group is an aldol. Figure 7 shows examples of aldols.

Figure 7. Aldols.

Acetaldehyde is the simplest compound that has alpha hydrogens. Therefore, the common name of the aldol made the self-aldol addition reaction of acetaldehyde is called aldol. All other aldehydes or ketones that contain the β-hydroxycarbonyl structure are members of the aldol family and are called aldols.

Crossed-Aldol Addition Reaction

In a self-aldol addition reaction, both reactants come from the same compound. When the two reactants in Step 2 come from different compounds, the reaction is called a crossed-aldol addition reaction.
A crossed-aldol addition reaction generally involves one aldehyde or ketone without alpha hydrogens and one with alpha hydrogens; therefore, only the compound with alpha hydrogens can form an enolate in base. If both compounds contained alpha hydrogens, then multiple products would be produced. The enolate is the nucleophile that adds to the carbonyl group of the compound without alpha hydrogens. Benzaldehyde contains no alpha hydrogens and acetone contains six equivalent alpha hydrogens; therefore, these two compounds can undergo a crossed-aldol addition reaction without forming multiple products. Figure 8 shows the structures of benzaldehyde and acetone. You should know the structures of these compounds. Figure 8. Benzaldehyde and acetone.

By inspecting the structures in Figure 8, we see that benzaldehyde has no alpha hydrogen atoms and acetone does. Thus, when these compounds are placed in base, acetone will form an enolate by the mechanism shown in Figure 4. The enolate serves as the nucleophile that adds to the carbonyl group of benzaldehyde, which serves as the substrate in the addition reaction. Figure 9 shows the reaction.

Figure 9. Synthesis of an aldol.

In Step 1, base removes an alpha hydrogen atom from acetone (the only reactant with alpha hydrogens), forming the cabanion or enolate that serves as the nucleophile. In Step 2, the negative carbanion adds to the positive carbonyl carbon to form the oxyanion. In Step 3, the adduct from Step 2 abstracts a proton from solvent to form the aldol (β-hydroxyketone) product. Note that the aldol addition and Grignard reactions are similar; they differ only in how the nucleophile is made. The nucleophile in an aldol reaction is formed from an aldehyde or ketone with alpha hydrogens; the nucleophile of a Grignard reagent is formed from an alkyl halide.

Aldol Condensation Reaction

We learned first semester that alcohols can eliminate water to form an alkene. Aldols are alcohols, and they can also eliminate water to form alkenes. Thus, initially formed aldols eliminate water when they are heated, generally in acid. Recall that a mineral acid protonates a hydroxyl oxygen atom, making a good leaving group. Consider aldol itself. Figure 10 shows that two different alkenes are possible when water is eliminated. In one alkene, the hydroxyl group and another alpha hydrogen are eliminated. In the second alkene, the hydroxyl group and a gamma hydrogen are eliminated.

Figure 10. Dehydration of aldol.

The dehydration of aldol gives only the α,β-unsaturated aldehyde, because it is more stable than the β,γ-unsaturated aldehyde. When an aldol is heated, it dehydrates to give an α,β-unsaturated aldehyde or ketone. Thus, an aldol reaction may be stopped after Step 3 to give an aldol, or after Step 4 to give an α,β-unsaturated aldehyde or ketone. When the reaction sequence includes Step 4, the overall reaction is an aldol-condensation reaction. Condensation implies the loss of water (or another small molecule such as ethanol) from two organic reactants. Figure 11 shows Step 4 that changes the aldol addition in Figure 9 into an aldol-condensation reaction.

Figure 11. Conversion of an aldol to an α,β-unsaturated ketone.

The Experimental Reaction

In this experiment, we conduct an interesting aldol condensation that involves one ketone that has α-hydrogen atoms (dibenzyl ketone) and one that does not (benzil). Thus, dibenzyl ketone will serve as the nucleophile, because it will donate a proton to a base to form an enolate. The overall reaction is shown in Figure 12.

Figure 12. Double-crossed aldol condensation.

This reaction involves two different ketones, so the reaction is described as a crossed-aldol condensation. Note that we have formed two α,β-unsaturated groupings, so the crossed aldol reaction occurs twice. Thus, the reaction can be called a double-crossed aldol condensation. You can work out the mechanism for the reaction by forming an enolate from dibenzyl ketone in base, allowing it to attack on carbonyl group in benzil, and eliminating water from the adduct. Repeat the process with the remaining α-hydrogen atoms while closing the five-membered ring. The final product is a purple solid.
Procedure

1. Set up a sand bath on your lab bench. [Metallic heating mantle, sand, and rheostat] Adjust the setting on the rheostat to 70.

2. Add 0.1-g benzil, 0.1-g dibenzyl ketone, 1.5-mL absolute ethanol, and a tiny boiling chip to a 15-mL round-bottomed flask. [Use a creased, glassine paper to transfer the solids.]

3. Attach a condenser from a micro kit to the round-bottomed flask with the blue adapter from the kit.

4. Affix the condenser-flask to a ring stand so that the round-bottom flask is slightly into the sand of the sand bath.

5. Heat the mixture on the sand bath until the solids dissolve but do not let the ethanol boil (bp = 78 oC).

6. Slowly add seven drops of 5% (weight-volume) alcoholic potassium hydroxide (KOH) through the condenser.

7. Bring the ethanol to a boil and allow the mixture to reflux for 10 min.

8. If a solid begins to form and cake on the round-bottomed flask, add a few drops of absolute ethanol to keep the solid moist.

9. While the mixture is under reflux, prepare an ice-water bath in a beaker large enough to hold the round-bottomed flask.

10. Remove the apparatus from the sand bath and allow the round-bottomed flask to cool to room temperature.

11. Place the flask, still attached to the condenser, in the ice-water bath and allow the flask to come to the temperature of the ice bath.

12. Remove the condenser and collect the crystals on a Büchner funnel.

13. Continue to apply suction until the crystals are as dry as possible.

14. Weigh the crystals and record the yield directly in your notebook.

15. Show the crystals to your instructor, who will tell you what to do with them.

16. Clean your work area. Replace all equipment to the correct storage location.…...

Similar Documents

Free Essay

Organic Compound Research Paper: Cinnamaldehyde

...to ancient times when it was first discovered, Cinnamon had great value. People living in biblical times used it as a perfume or anointing oil, while Egyptians used it in the burial of their mummies. Each civilization had a different use for it, but in all civilizations it was an item of worth. Cinnamaldehyde has many other names to describe it, but the most common name (other than its common name Cinnamaldehyde) is its IUPAC name: (2E)-3-phenylprop-2-enal, or 3-phenyl-2-propenal. Its formula is C6H5CH=CHCHO, it is in the family of aldehydes, and the Merck Index Number is 2297. Also, its structures are showed below: Structure: Ball and Stick Method Structural Formula And, a common reaction of Cinnamaldehyde is an aldol condensation reaction, which is the first reaction that occurs when Cinnamaldehyde is being synthesized to obtain commercial cinnamon. It is shown below: As stated previously, Cinnamaldehyde is found in the bark of an evergreen tree native to Southern India/Sri Lanka. This bark can be used to make Cinnamon. Cinnamon then became a valuable possession in the ancient times; it was a luxury to own. In biblical times, Egyptian times, and Roman times, Cinnamon was especially important. Cinnamon is not seen as something with monetary value nowadays, but we still use it today as a flavor in foods, and scents in things such as candles. Besides Cinnamaldehyde’s obvious involvement as a food additive (in things such as gum, cinnamon......

Words: 814 - Pages: 4

Free Essay

Tetraphenylcyclopentadienone

...Tetraphenylcyclopentadienone Introduction The purpose of this experiment was to synthesize tetraphenylcyclopentadienone by reacting dibenzyl ketone with benzil in the presence of a base. The reaction proceeded via an aldol condensation reaction with dehydration, and then the product crystals were isolated by vacuum filtrations using a Buchner funnel. Experiment Scheme Equation 1. Aldol condensation reaction between benzil and dibenzyl ketone in the presence of a base To begin the experiment 1.5g of benzil, 12mL absolute ethanol and 1.5g of dibenzyl ketone were added to a 50-mL round bottom flask. A stir bar was added and the flask was attached to a condenser and heated in a water bath to 70◦C. The mixture was heated with sitting until the solids dissolved. Once solids were dissolved the temperature was raised to 80◦C with stirring. Using a Pasteur pipet, 2.25mL of ethanolic potassium hydroxide were added drop wise downward through the condenser into the flask. The mixture turned deep purple. After this, the temperature was raised to 85◦C and remained at that temperature with stirring for 15 minutes. After the heating period the flask was removed from the hot water bath and cooled to room temperature. Once at room temperature the flask was placed in ice-water bath for 5 minutes to complete crystallization of product. Using a Buchner funnel we collected the deep purple crystals. The crystals were washed with three 4-mL portions of cold 95% ethanol. The...

Words: 710 - Pages: 3

Premium Essay

Organic Chemisty

...Alkanes Preparation: 1. Hydrogenation of alkenes 2. Hydrogenation of alkynes 3. Reduction of alkyl halides 4. Coupling of alkyl halides (Wurtz reaction) 5. Hydrolysis of Grignard reagent Reaction: 6. Oxidation 7. Halogenation Cycloalkanes Preparation: 1. Carbene insertion 2. Simmons-Smith reaction 3. Modified Wurtz reaction 4. Dieckmann condensation Reaction: 5. Opening reactions of three- and four-membered rings 6. Halogenation 7. Oxidation Alkenes Preparation: 1. Dehydrohalogenation of alkyl halides (E2 Elimination) 2. Acid-Catalyzed Dehydration of alcohols 3. Dehalogenation of vicinal dihalides Reaction: 4. Halogenation 5. Hydrohalogenation 6. Addition of HBr in Peroxide 7. Hydration 8. Oxymercuration-Demercuration 9. Hydroboration-oxidation 10. Catalytic hydrogenation 11. Epoxide formation 12. Oxidation 13. Ozonolysis cleavage 14. Cationic polymerization 15. Free-radical polymerization 16. Addition of halogens and water (Halohydrin formation) Alkynes Preparation: 1. Dehydrohalogenation of vicinal and germinal dihalides 2. Dehalogenation of vicinal tetrahaloalkanes 3. Substitution Reaction: 4. Hydrogenation 5. Hydrohalogenation 6. Halogenation 7. Hydration (keto-enol tautomerization) 8. Reaction of acidic terminal hydrogen (acid-base reaction) Alkyl Halides Preparation: 1. Addition of......

Words: 623 - Pages: 3

Free Essay

A Case Study in Condensation

...A case study in condensation Evaluating and preventing attic condensation in a residential building by Sammy Condensation on the undersides of roof decks in attics can be a common problem for different residential roof systems. Condensation in attics can occur more frequently in the colder climates of the upper Midwest and Northeast and typically on roofs that have inadequate ventilation and insulation, as well as attic bypasses. When dryer vents, bathroom fans or furnace exhaust ducts vent directly into an attic space, the problem is intensified. |[pic] | |Photos courtesy of Wiss, Janey, Elstner | |Associations Inc., Minneapolis. | |Photo 1: Brown stains on the underside of a | |ceiling in one townhouse | Although building codes recommend and require adequate attic ventilation above roof insulation to remove heated air and water vapor that has entered an attic from the surrounding air or a structure's occupied portion, the codes are not strictly adhered to during the design or construction phases. In addition, attic bypasses and openings in dryer vents and furnace ducts must be sealed to minimize moisture infiltration into an attic. This would prevent troublesome condensation within the attic space and on the roof deck's underside. Unfortunately, joints in vents and furnace ducts sometimes are not installed in an airtight manner. The primary signs of severe condensation in an attic......

Words: 1978 - Pages: 8

Premium Essay

Evaluation of L – Proline as a Catalyst for an Asymmetric Aldol Reaction

...Evaluation of L – Proline as a Catalyst for an Asymmetric Aldol Reaction Abstract This reaction is divided into two parts. In the first part acetone, L – proline and 4 – nitrobenzaldehyde are reacted to give (R)-4-hydroxy-4-(4-nitrophenyl)butan-2-one as the major product along with (S)-4-hydroxy-4-(4-nitrophenyl)butan-2-one. The identity of the product is confirmed by IR spectra of the product which gives peaks at 1073.94 cm-1, 1330 cm-1, 1515.05, 1600.13 cm-1, 1708.25 cm-1, 2930.82 cm-1and broad peak at 3418.10 cm-1. The mass of the product is 0.013 grams which gives a percentage yield of 29.81%. The melting point of the product is not taken due to minimal product. In the second part of the reaction excess reagents are used and the synthesized product is in very small quantities. The product synthesized is diastereomers of 1-(4-nitrophenyl)-3-oxobutyl 3,3,3-trifluoro-2-methoxy-2-phenylpropanoate. The identity of this compound is confirmed by the following peaks seen in 1H NMR: 8.19 and 7.62 ppm, 5.47 ppm, 2.90, 2.13 ppm, 3.30 ppm, 7.36 – 7.38 ppm. The melting point, IR spectrum, theoretical yield or percentage yield is not found since all of it used in 1H NMR analysis. The product 1H NMR shows a mix of both the diastereomers, but it is difficult to ascertain which one is in excess. Introduction The aldol reaction that was experienced in this lab is the nucleophillic addition of an enolate to a carbonyl group to form a B-hydroxycarbonyl. This reaction is a very......

Words: 2273 - Pages: 10

Free Essay

Organic Chemistry Note

... 74 Section F – Reactions and mechanisms Table 1. Different categories of reaction undergone by functional groups. Functional group Alkenes and alkynes Aromatic Aldehydes and ketones Carboxylic acid derivatives Alkyl halides Alcohols and alkyl halides Alkenes, alkynes, aromatic, aldehydes, ketones, nitriles, carboxylic acids, and carboxylic acid derivatives, Alkenes, alcohols, aldehydes Carboxylic acids, phenols, amines Section H I J K L M,L H–N Reaction category Electrophilic addition Electrophilic substitution Nucleophilic addition Nucleophilic substitution Elimination Reduction Oxidation Acid/base reactions H–N G reactions are so important that they are named after the scientists who developed them (e.g. Grignard and Aldol reactions). Another way of categorizing reactions is to group similar types of reactions together, depending on the process or mechanism involved. This is particularly useful since specific functional groups will undergo certain types of reaction category. Table 1 serves as a summary of the types of reactions which functional groups normally undergo. Section F – Reactions and mechanisms F2 MECHANISMS Key Notes Definition A mechanism describes how a reaction takes place by showing what is happening to valence electrons during the formation and breaking of bonds. Curly arrows are used to show what happens to valence electrons during the making and breaking of bonds. They always start from the source of two electrons (i.e. a......

Words: 119372 - Pages: 478

Free Essay

Hi Its Pravin Kumar.

...Problems can be asked from any lesson or chapter instead of descriptive questions and vice versa. 5. Problems Part - I Part - II Part - III Part - IV MCQ 4 questions 3 questions Inorganic - 1 question Physical - 1 question 4 x 1 = 4 (1+2+1) 3 x 3 = 9 (1+1+1) 2 x 5 = 10 question no 70 is compulsory, either or choice 2 x 10 = 20 marks maximum marks 4 + 9 +10 + 20 = 43 marks. 6. A question paper should not contain problems for more than 43 marks out of 233 marks. 7. Organic reaction mechanicsm may be asked one in Part-III Section-C (organic) and another in Part-IV question number 68 or 69 subdivision for 5 marks. 8. List of Mechanisms (i) (ii) EM. Page No. Aldol condensation of acetaldehyde ..................... 281-282 Aldol condensation of acetone ............................. 282-283 (iii) Crossed aldol condensation ................................... 283 (iv) Cannizaro reaction ................................................. 300 (v) Claisen or Claisen schmidt reaction ........................ 301 (vi) Mechanism of esterification .................................... 336 (vii) Kolbe’s reaction ..................................................... 355 3 (viii)Bromination of salicylic acid .................................... 356 (ix) Nitration of benzene ............................................ 387-388 (x) Hoffmann’s bromamide reaction .......................... 398-399 (xi) Reaction of aniline with carbondisulphide ........... 411 - 412 For other organic......

Words: 1341 - Pages: 6

Premium Essay

Chemistry

...NAME: AKINWANDE OLUFISAYO PARNTNER: COURTNEY DATE: JULY 8TH 2014. ALDOL CONDENSATION TO MAKE VANILIDENEACCETONE. DATA: REACTION: TABLE 1: DATA FROM EXPERIMENT | Vanillin | Acetone | Vanillindeneacetone | Chemical formula | C8H803 | C3H60 | C11H1203 | Molecular weight | 152.25 g/mol | 58.08 g/mol | 192.21g/mol | Density (g/cm3) | 1.06 | 0.788 | | Amount used | | | | Total moles | | | | Theoretical yield | | | | Percentage yield | | | | TABLE 2: DATA FROM EXPERIMENT: REAGENTS | Sodium Hydroxide | Hydrochloric Acid | Chemical formula | NaOH | HCl | Molecular weight | 39.997 g/mol | 36.46 | Denisty | 2.13 | 1.18 | Amount used | 3mL | 7mL | Total moles | 0.i598 | 0.227 | TABLE 3 : IR SPECTRUM Peaks (cm-1) | Functional group | 3699.8 | OH group | 3267.6 | Alkene | 1634.79 | Aromatic | CALCULATIONS: Total moles of Vanillin = 0.5g/152.15 = 0.0033 moles of vanillin. Total moles of acetone = (4mL * 0.788)/ 158.08 = 0.0199 moles of Acetone. Theoretical yields: Vanillin = 0.5g * 1mole * 1mole * 192.21 = 0.632g 152.15 1mole 1mole Acetone = 4ml * 0.788 * 1mole * 1mole * 192.21 = 3.832g 1mole 158.08 1mole 1mole Therefore, vanillin is the......

Words: 487 - Pages: 2

Premium Essay

Lab 5 – Weather and Climate Change

...processes that are represented in this model are condensation and evaporation. Condensation occurs under the lid of the jar. Some of the water in the jar evaporated. 2. Which processes are not represented? How could the model be altered to include these processes? Answer = Infiltration, Surface run-off, percolation, precipitation, transpiration, sublimation. I don’t see how you can change this experiment, unless you add more supplies. 3. How would the “weather” be affected if the water was at a decreased temperature? What about at an increased temperature? Answer = with decreased temperature the weather would be smooth compared to increased temperatures were things would be rough. Experiment 1: Water Movement POST LAB QUESTIONS 1. Develop a hypothesis predicting the effect of sunlight on evaporation? Hypothesis = By placing one bag of sand in direct sunlight and placing the other bag of sand in a shaded area, I believe the bag that’s in direct sunlight will show evaporation and condensation occur compared to the bag that’s in a shaded area. 2. Based on the results of your experiment, would you reject or accept the hypothesis that you produced in question 1? Explain how you determined this. Accept/reject = I would accept my hypothesis because the bag of sand that’s in direct sunlight did show that evaporation and condensation occur within the bag. The bag that was......

Words: 356 - Pages: 2

Free Essay

Phed

...the initial conversion of acetone to its cyanohydrin: (CH3)2CO + HCN → (CH3)2C(OH)CN In a subsequent step, the nitrile is hydrolyzed to the unsaturated amide, which is esterified: (CH3)2C(OH)CN + CH3OH → CH2=(CH3)CCO2CH3 + NH3 The second major use of acetone entails its condensation with phenol to give bisphenol A: (CH3)2CO + 2 C6H5OH → (CH3)2C(C6H4OH)2 + H2O Bisphenol-A is a component of many polymers such as polycarbonates, polyurethanes, and epoxy resins. Combustion (CH3)2CO + 4O2 → 3CO2 + 3H2O As a solvent Acetone is a good solvent for most plastics and synthetic fibres including those used in Nalgene bottles made of polystyrene, polycarbonate and some types of polypropylene.[3]. It is ideal for thinning fiberglass resin, cleaning fiberglass tools and dissolving two-part epoxies and superglue before hardening. It is used as a volatile component of some paints and varnishes. As a heavy-duty degreaser, it is useful in the preparation of metal prior to painting; it also thins polyester resins, vinyl and adhesives. Many millions of kilograms of acetone are consumed in the production of the solvents methyl isobutyl alcohol and methyl isobutyl ketone. These products arise via an initial aldol condensation to give diacetone alcohol.[2] 2 (CH3)2CO → (CH3)2C(OH)CH2C(O)CH3 Acetone is used as a solvent by the pharmaceutical industry and as a denaturation agent in denatured alcohol.[4] Acetone is also present as an excipient in some pharmaceutical products.[5] Storage of......

Words: 2033 - Pages: 9

Free Essay

Dynamic Condensation

...Institut für Wasserkraftmaschinen und Pumpen SE Hydraulische Energiesysteme LVA Nr. 305.011 Das Laufrad von Peltonturbinen (Konstruktive Lösungen) erstellt von: 305.011 SE Hydraulische Energiesysteme Inhaltsverzeichnis 1 2 3 Einleitung: ................................................................................................................ 3 Historischer Überblick .............................................................................................. 3 Klassische Bauweisen ............................................................................................. 5 3.1 Reiterbauweise................................................................................................. 5 3.2 Monoblockguss ................................................................................................ 6 4 Aktuelle Entwicklungen ............................................................................................ 7 4.1 Der MicroGussTM Prozess ................................................................................ 7 4.2 Der HiweldTM Prozess ...................................................................................... 9 4.3 Die EFG-Formschlussbauweise..................................................................... 11 5 Weitere Bauweisen ................................................................................................ 13 5.1 Anschweißen der Becher ..............................................................

Words: 2598 - Pages: 11

Free Essay

Ch 220c

...you have any problems or feel your frustration level rising, please don’t hesitate to talk to us. Here’s to a successful, enjoyable semester! 13. WORK SCHEDULE LAB REPORT DUE DATE SCHEDULE* |Report |Due |Report |Due |Report |Due | |Distillation |Period 4 |Substitution |Period 8 |Luminol |Period 12 | |Extraction |Period 6 |Grignard |Period 9 |Dehydrobromination |Period 12 | |Stereochemistry |Period 6 |Aldol Condensation |Period 10 |EAS |Period 13 | |Arenes |Period 7 |9-Fluorenone |Period 10 |Azo Violet |Period 13 | |Stilbene |Period 7 |Methyl Benzoate |Period 11 | | | * All reports are due at the beginning of the period. Be sure to Submit Post lab reports to Turn-It-In. EXPERIMENTS |REQUIRED PRE-LAB PREPARATION! Read about the techniques listed at the start of each experiment in preparation for working in the laboratory. | |Period 1 ......

Words: 8040 - Pages: 33

Premium Essay

Biochem Task 4

...energy ("Enzyme," n.d.) Retrieved from http://commons.wikimedia.org/wiki/File:Enzyme_decreases_the_activation_energy.png A4. Substrate Aldolase B acts on the substrate fructose 1-phosphate, and cleaves it into dihydroxyacetone phosphate and glyceraldehyde. ("Aldolase B," n.d.) Fructose 1-phospate is generated when fructose enters the liver, and is acted on by fructokinase. This process is called “fructolysis”. A5. Role of Aldolase B Aldolase B cleaves fructose 1-phosphate, a 6-carbon fructose sugar, into two 3-carbon molecules. This process is a reverse aldol reaction. This process forms a Schiff base, a compound with a functional group that contains a carbon-nitrogen double bond, the nitrogen atom connected to a non-hydrogen aryl or alkyl group. ("Schiff base," n.d.) When a Schiff base is formed, an aspartate residue deprotonates the fourth hydroxyl group that lies on the fructose “backbone”. This causes aldol cleavage. The two three-carbon molecules formed by this reaction are dihydroxyacetone phosphate and glyceraldehyde. Triose kinase phosphorylates glyceraldehyde to form glyceraldehyde-3-phosphate. Both products can be changed to become either pyruvate or glucose. B. Case 2: The Cori (Lactic Acid) Cycle and the Citric Acid (Kreb’s) Cycle B1. Interconversions of Cori Cycle Skeletal muscles have few mitochondria for ATP (energy) production, yet need energy during activity. The lactate that is made by anaerobic glycolysis in the muscles is moved to......

Words: 1387 - Pages: 6

Free Essay

Aldol

...212 g (pure product) | Percentage Yield Calculations: Supporting Data and Documentation: Name | Data | Benzaldehyde | 2.683 g | Acetone | 0.776 g | NaOH | 2.514 g | Water | 25 mL | Ethanol | 20 mL | Empty funnel | 15.597 g | Funnel with crude product | 18.959 g | Empty funnel | 15.786 g | Funnel w/ pure product | 17.998 g | Melting pt range (crude product) | 101˚C | Melting pt range ( pure product) | 105˚C | Results and Discussion: In this experiment the ethanolic solution composed of Acetone and Benzaldehyde were added to the aqueous sodium hydroxide. The two moles of belzaldehyde acted in response with both acidic α-protons of the acetone. Throughout the combination dehydration of the aldol product occurred. Dibenzalacetone, the final product, was precipitated right after mixing all the solutions with a yellow color and a pleasant smell. The product was then filtered from the combination, washed away, constrained dried and recrystallized from the hot ethanol. Melting point range were determined after crystallization with 101˚C and recrystallization with a 105˚C, which is very close to the melting point in the text book (113˚C). Percent yield of the recrystallization was calculated with a 72.62 %. Some of the final product was lost while doing the recrystallization. Infrared Spectroscopy was also determine. The IR Spectrum was very similar to the one in the book. The first peak......

Words: 752 - Pages: 4

Premium Essay

Grt1

...energy ("Enzyme," n.d.) Retrieved from http://commons.wikimedia.org/wiki/File:Enzyme_decreases_the_activation_energy.png A4. Substrate Aldolase B acts on the substrate fructose 1-phosphate, and cleaves it into dihydroxyacetone phosphate and glyceraldehyde. ("Aldolase B," n.d.) Fructose 1-phospate is generated when fructose enters the liver, and is acted on by fructokinase. This process is called “fructolysis”. A5. Role of Aldolase B Aldolase B cleaves fructose 1-phosphate, a 6-carbon fructose sugar, into two 3-carbon molecules. This process is a reverse aldol reaction. This process forms a Schiff base, a compound with a functional group that contains a carbon-nitrogen double bond, the nitrogen atom connected to a non-hydrogen aryl or alkyl group. ("Schiff base," n.d.) When a Schiff base is formed, an aspartate residue deprotonates the fourth hydroxyl group that lies on the fructose “backbone”. This causes aldol cleavage. The two three-carbon molecules formed by this reaction are dihydroxyacetone phosphate and glyceraldehyde. Triose kinase phosphorylates glyceraldehyde to form glyceraldehyde-3-phosphate. Both products can be changed to become either pyruvate or glucose. B. Case 2: The Cori (Lactic Acid) Cycle and the Citric Acid (Kreb’s) Cycle B1. Interconversions of Cori Cycle Skeletal muscles have few mitochondria for ATP (energy) production, yet need energy during activity. The lactate that is made by anaerobic glycolysis in the muscles is moved to......

Words: 1388 - Pages: 6