01:160:308 Lecture Notes - Lecture 19: Diazomethane, Hydrogenation, Lithium Aluminium Hydride

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17 Apr 2018

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17. 1 structure: the carboxylic acid (-cooh) contains a carbonyl group bonded to an -oh group. 17. 4 acidity: values for the pka for alipathic carboxylic acids are in the range of 4. 0-5. 0, the greater the acidity of carboxylic acids compared with alcohols is explained by the charge delocalization through resonance in a carboxylate. Ch17: carboxylic acids anion relative to an alkoxide ion and the electron- withdrawing inductive effect of the carbonyl group: electron-withdrawing substituents near the carboxyl group increases its acidity. 17. 7 esterification: fischer esterification is the preparation of an ester by treating a carboxylic acid in the presence of an acid catalyst such as sulphuric acid. Fischer esterification is reversible: treating a carboxylic acid with diazomethane (ch2n2) gives a methyl ester in high yield. 17. 8 conversion to acid chlorides: acid chlorides are prepared from a carboxyl group by treatment with thionyl chloride (socl2).

Related Questions

Total amount of dye obtained (crystal violet) = 6.5mL

The absorbance using UV spectrometer is =1.75

Please help within the following

Using the reported value of the extinction coefficient of 112,000 M^-1 cm^-1, calculate the concentration of diluted sample and (according for dilution ) estimate the percent yield of this reaction by determining the number of moles of the dye formed. You can assume that the dye follows the Beer-Lambert Law and that A=ebc which for a 1cm cell simplifies to Absorbance A= ( 112,000 M^-1 cm^-1)(1.00cm) (concentration of crystal violet).

Please help thank you!

Organic Laborat 2. The Grignard Reaction: Preparation of Crystal Violet Reference: Journal of Chemical Education, 73, 259, (1996) Douglass Taber, Robert Meagley and Danielle Supplee Laboratory Objectives: 1. Prepare a Grignard Reagent from a bromoaromatic compound and magnesium. 2. Perform a water sensitive reaction at a micro-scale. 3. Observe the visible color of a highly conjugated triphenylmethyl dye. 4. Predict reaction products expected from the reaction of Grignard Reagents with carbonyl compounds. Introduction: The Grignard Reaction is a chemical reaction which to form the Grignard reagent would be classified as a reduction. Magnesium reacts with alkyl and aryl halide to form an organometallic reagent which can subsequently react as a carbon nucleophile in a chemical reaction. Grignard reagents can be stored as THF solutions but it is common to make the organometallic compound and then react it without work-up with some suitable compound. This could be carbon dioxide to form a carboxylic acid or water or deuterium oxide to form the reduced hydrocarbon. More commonly carbonyl compounds (organic compounds which contain a C-O group) are used to form the addition product of the organometallic compound and the carbonyl group. This results in an alcohol if aldehydes and ketones are used as the carbonyl group. If the carbonyl group used is an ester (R-COp-R') then the nucleophilic addition to the carbonyl carbon occurs as expected but the carbonyl is reformed by loss of the alkoxide ion. This new carbonyl compound can add an additional mole of organometallic reagent to again give an alcohol but one that contains two of the organic groups from the Grignard reagent. In this reaction you will prepare an aromatic organometallic reagent which will react with diethyl carbonate. Diethyl carbonate will perform the reaction described for esters above but since there are two alkoxide groups that can leave, this results in the addition of not two but three moles of the Grignard reagent. Also the product expected would be a tertiary alcohol in which each of the carbon groups is aromatic. The triphenyl methyl group is commonly called a "trityl" group and since the central carbon is both tertiary and benzylic to each of the rings the alcohol that might be expected will quickly dehydrate to give a stable carbocation (a so-called trityl or triphenylmethyl cation). In the compound that you will prepare called Crystal Violet or Gentian Violet the cation is not only a trityl cation but each of the rings has a dimethylamino group in the para position. These groups being electron donating by resonance will also help to stabilize the cation. This highly conjugated compound will absorb visible radiation and will be highly colored. This compound has been used as a dye in commercial applications including biological staining.

Test 1-Multiple Choice: Choose and underline the best answer in each of the following statement/question.

_____1. Which of the following best differentiates an aldehyde from a ketone?

a. In aldehydes, carbon is bonded to a hydroxyl group.

b. In aldehydes, hydrogen is bonded to an oxygen group.

c. In aldehydes, hydrogen is bonded to a carbonyl group.

d. In aldehydes, oxygen is bonded to an oxygen group.

_____2. Which of statement is not true about petroleum and its products?

a. Petroleum is fossil fuel.

b. Petroleum is a mixture of hydrocarbons with sulfur as impurity.

c. There is no harm that comes from the use of petroleum products.

d. Petroleum comes from decomposition of materials of living origin.

_____3. Cooking gas or liquefied petroleum gas(LPG) is a mixture of C₃H₈ and C₄H₁₀. Which are these compounds?

a. pentane and butane b. methane and butane

c. propane and butane d. propane and methane

_____4. Which of the following compounds ionizes in water and, thus conducts electricity poorly?

a. acetic acid b. hydrochloric acid c. distilled water d. sodium hydroxide

_____5. A lead storage cell can function both as an electrolytic cell and as a voltaic cell. When a lead storage battery is being recharged, it converts ________ energy to_____--energy

a. chemical : electrical b. chemical to heat c. electrical to mechanical

_____6. The acid electrolyte in a lead storage battery is

a. HCl b. H₂SO₄ c. HNO₃ d. CH₃COOH

____7. The anode and cathode in a dry cell respectively are

a. Zn and C b. C and Zn c. Pb and PbO₂ d. PbO₂ and Pb

____8. What is the proper name for the compound CH₃CH₂CH₃?

a. ethane b. propane c.butane d. pentane

____9. Which of the following is the simplest hydrocarbon?

a. CH₂ b. C₂H₄ c. CH₃ d. CH₄

____10. Hydrocarbons such as CH₂ =CH₂ are said t be

a. ionic b. aromatic c. saturated d. unsaturated

_____11. Which of the following best describes hydrocarbons?

a. flammable ionic compounds that are insoluble in water and are denser than water

b. flammable ionic compounds that are insoluble in water and are denser than water

c. flammable covalent compound that are insoluble in water and are less dense than water

d. flammable covalent compounds that are soluble in water and less dense than water

_____12. Which of the following will result if hexane and water are mixed?

a. an explosion

b. clear solution of hexane dissolved in water

c. a layer of hexane on top of a layer of water

d. a layer of water on top of a layer of hexane

_____13.Which of the following is not a gas?

a. ethene b. octane c. methane d. acetylene

_____14. Which of the following is another name for wood alcohol?

a. methanol b. propanol c. grain alcohol d. rubbing alcohol

_____15. Which of the following alcohols groups are found in beverages?

a. ethyl b. methyl c. denatured d. wood

_____16. Which of the following is the only element present in organic compounds?

a. hydrogen b. oxygen c. carbon d. nitrogen

_____17. Which of the following is chlorofluorocarbon?

a. C₃F₈ b. CHF₃ c. CFCl₃ d. CHCl₃

_____18.What percent of alcohol is present in vodka which is 90 proof?

a. 9 b. 45 c. 90 d. 180

____20. Which of the following is formed when carbohydrates undergo fermentation process?

a. ethanol b. methanol c. glucose d. formaldehyde

_____21. In ethene, the two carbon atoms are joined by a

a.single bond b. double bond c. triple d. ionic

____22. The IUPAC name of CH₃CH₂CHCH₂CH₃ is

CH₂CH₃

a. 3-methylpentane b. 3-ethylpentane c. 2-ehtylpentane d. 2-methylpentane

____23. The IUPAC name of CH₃-O-CH₃ is

a. methoxymethane b. ethylether c. dimethylether d. dimethyloxide

____24. Which is an alcohol?

a. C₆H₆

b. CH₃-C-CH₃

c. CH₃-O-CH₃

d. CH₃OH

____25. A group which both aldehydes and ketones have in common is

a.-C=O b. âOH c. âO- d. -COOH

___26. The aroma associated with this class of compounds is regarded as pleasant.

a. amides b. esters c. carboxylic acids d. ketones

____27. The IUPAC name of CH₃CH₂CHO is

a. propanone b. propanol c. propanal d. propionic acid

____28.The âCOOH group is called

a. aldehyde group b. hydroxyl group c. carbonyl group d. carboxylic group

____29.The alkyl group of butane is

a. C₂H₃ b. C₃H₅ c.C₄H₇ d. C₄H₉

____30. The simplest alkene is

a. CH=CH b. CH₂=CH₃ c. CH₂=CH₂ d. CH₃CH=CH₂

Test 2. Answer the following questions completely.(3 points each)

1.Why are alcohols of lower molecular weight more soluble in water than those with higher molecular weights?

2. Which of the following pairs of compounds has

a. higher bolilng point:1-bromopentane or 1-chloropentane _____________________

b. the greater density: heptanes or octane ______________________
c. the higher boiling point :pentyl alcohol or pentylamine ______________________

d. the higher boiling point: hexylamine or dipropylamine ______________________

3. Explain why each of the following names are incorrect.Give the correct IUPAC name.

a. 3-Butanone

b. 1-Butanone

4. What is unique about carbon atom that makes it form numerous compounds?

5. Acetone or propanone is completely soluble in water,but 4-heptanone is completely insoluble.Explain.

Test 3.. Give the name and chemical formula of the functional group of each of the following organic groups. The first one has been done for you.

Organic Group	Functional chemicalfFormula	Functional group name
1.Alkanes	-C-C-	carbon carbon single bond
2.Alkenes
3.Alkynes
4.Alcohols
5. Aldehydes
6. Ketones
7. Thiols
8. Ethers
9.Carboxylic acids
10.Esters
11. Amines
12. Amides

01:160:308 Lecture Notes - Lecture 19: Diazomethane, Hydrogenation, Lithium Aluminium Hydride

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