CHEM164 Study Guide - Midterm Guide: Phenylmagnesium Bromide, Gilman Reagent, Aldehyde

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violetminnow578

12 Jun 2015

School

University of Alberta

Department

Chemistry

Course

CHEM164

Professor

Ratmir Derda

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Document Summary

Lecture notes chapters 11,12, and 14: alcohols, ethers, and epoxides (review, in part!: alcohols and ethers. Bidensyneoside b glycosidic natural antiallergenic (from bidens parviflora wild) Crown ethers: synthetic ionophores (nobel prize to pedersen, cram, and lehn, 1987) O furan pyran tetrahydrofuran oxirane or ethylene oxide (an epoxide) Alcohols are weakly lewis basic (typical of oxygen lone pair): Alcohols are also weakly br nsted acidic (pka ~ 16-19, similar to h2o): Acidity (pka): hoh (15. 7) > etoh (17) > rc ch (25) > h2 ~ r2nh (35) > r h ( 50) Hydrogen bonding: strongly dipolar o h bond creates extensive bonding interactions: Synthesis of alcohols: review for some (i hope) (1) acid-catalyzed hydration of alkenes. A reaction of limited utility due to competition from the reverse reaction (sn1 elimination) and carbocation rearrangements. Chemistry 263 (2) oxymercuration and hydroboration of alkenes. R: b2h6 or bh3 thf (1/6 or 1/3 equiv, resp. , h2o2, naoh, h2o.

Related Questions

Â¥Write a brief (less than 150 words, 3 or 4 sentences) of the aim of the experiment

Â¥Address question of what was done, how it was done, and what compounds were used.

Â¥Include Chemical Reaction where relevant.

See text below. Please provide Purpose following the steps above. Thank you.

Alcohols R-O-H are characterized by the presence of the hydroxyl group

Because of intermolecular co-association, alcohols show higher boiling points

than aldehydes, ethers, or ketones of similar mass. Among alcohols, boiling

points increase with increased surface area. Increased surface area occurs as

more carbons are added to the alkyl portion or with decreased branching of th

alkyl group. Thus, 1-propanol has a higher boiling point than ethanol

(increased C#). 1-propanol also has a higher boiling point than 2-propanol

(decreased branching)

The solubility of alcohols in water decreases as the surface area of the

alkyl (nonpolar) portion increases. Thus, alcohols become less soluble in water

as the number of carbons in the alkyl group increases. When comparing

alcohols that contain the same number of carbons, branching of the alkyl group

decreases its surface area and thus increases the water solubility of the alcohol.

1-Propanol is slightly soluble in water while 2-propanol is quite soluble

The limit of water solubility is reached at about 4 or 5 carbons in the

alkyl group. However, it is possible to "salt out" or separate a water-soluble

alcohol from the water it is mixed with by the addition of certain salts such as

K2CO3. If an alcohol-water mixture is saturated with such a salt, the anion

selectively forms strong ion-dipole bonds to water, leaving the alcohol as a

separate layer. Thus, water is separated from the alcohol because the ionic salt

bonds more strongly with water than with the alcohol. There are twice as many

ion-dipole bonds possible with water than with the alcohol.

Alcohols are relatively acidic organic molecules, being weaker acids than

water, yet stronger than acetylene.

Acidity: water > alcohol > acetylene > ammonia > alkanes

Alcohols may be converted to sodium alkoxides by the action of metallic sodium

under anhydrous conditions. Primary alcohols react more readily tharn

secondary or tertiary alcohols due to the relative stability of the alkoxide ions in

the solvent alcohol.

R-o:-

Alcohols undergo nucleophilic substitution reactions with ease under

acidic conditions. The relative ease of such substitution for primary, secondary

and tertiary alcohols serves as a means of classification. Upon treatment with

concentrated HC1, tertiary alcohols are rapidly converted to alkyl chlorides

Secondary alcohols require warming in a boiling water bath for 15 minutes

Primary alcohols do not react at all under these conditions. The alkyl chlorides

formed by this reaction are insoluble in the concentrated HCl and form an

easily detectable second layer

R-O-H HC1 >

Ð-Ð-Ð

Complications arise from the fact that benzylic and allylic alcohols also

react immediately, but yield products that are soluble in the concentrated HCI

Alcohols are easily oxidized by any of these strong oxidizing agents:

dilute KMnO4, NajCr.07 in acid, or CrO3 (chromic anhydride)

acidified sodium dichromate is somewhat helpful in the classification of

alcohols. Prim

ary and secondary alcohols are oxidized rapidly within several

minutes, while tertiary alcohols do not react under these conditions

Oxidation occurs more easily when the carbon bearing the -OH group

bonded to at least one atom of hydrogen. The complex mechanism of

involves the transfer of a hydride ion H:- as a critical step.

hydrogen atom is absent (as in tertiary alcohols), no oxidation can occur

directly. Tertiary alcohols may be oxidized indirectly through the formation of

Alcohols which contain the partial structure C- CH3 give positive

Ð¾Ð½

results in the iodofora reaction. When the alcohol is dissolved in water and

KOH, the addition of a solution of 12 in KI yields a yellow precipitate of

iodoform, CHI3, along with the oxidized portion of the alcohol

Hypoiodite ion is produced by the reaction between molecular iodine and

hydroxide ion:

I2 + 4(OH) -

The hypoiodite ion in turn oxidizes an alcohol with the proper structure

Once this oxidation has occurred, additional hypoiodite ion continues to

react with the aldehyde or ketone produced:

CH,-C

3 (0I)-IC-c3 (OH)-

resulting in the final substitution reaction to give iodoform and the anion of a

carboxylic acid containing one carbon atom less than the original alcohol:

128

lodoform precipitates as fine yellow crystals. This precipitate, a result of a

specific oxidation followed by a substitution, is an indication of the partial

structure of the original alcohol.

Simple alcohols of up to ten carbon atoms may be detected by the

ammonium hexanitrocerrata(lV) reagent, (NH4Ce(NO,). The hexanitro-

cerrate(IV) ion has a distinctive orange-red color. When an alcohol, ROH is

added, one or more OR- groups replace the nitro groups as ligands in the

complex ion. The new complex ion formed has a distinctive color. The general

equation for this reaction is:

This test is positive for aliphatic alcohols up to approximately ten carbons in

length. Phenols or larger alcohols yield insoluble mixtures

Alcohols react with acids or with acid derivatives to form esters. This

characteristic reaction is useful in the formation of specific esters such as ethyl

acetate, acetylsalicylic acid (aspirin) and methyl salicylate (oil of wintergreen). In

this experiment, methyl salicylate will be prepared by reacting methyl alcohol

with salicylic acid in the presence of a trace of sulfuric acid as the catalyst

Lower molecular weight alcohols such as ethanol, methanol, and

isopropyi alcohol absorb water on exposure to moist air or are prepared as

azeotropic mixtures containing water. The presence of water in alcohols may be

detected in several ways. If a small lump of CaC2 is added to any alcohol that

contains a trace of water, a reaction occurs that produces immediate bubbles of

acetylene gas:

Thus, evolution of acetylene gas upon the addition of calcium carbide indicates

the presence of water in the alcohol. Another way to test for the presence of

water in alcohols involves the use of anhydrous cupric sulfate powder (CuSO4)

Anhydrous cupric sulfate is a very pale, almost white powder. In the presence of

water, deep blue crystals of cupric sulfate pentahydrate,

CuSO4-5H20, are formed. Thus, anhydrous cupric sulfate indicates the

presence of water in an alcohol by a simple color change.

Commercial ethanol is produced as an azeotropic mixture that contains

95% ethanol and 5% water. Absolute alcohol contains no water. Many reagent

grade alcohols are composed of a nonpotable mixture of 95% ethanol and 5%

isopropyl alcohol. Thus, absolute ethanol and reagent alcohols are both water

free and give negative results when tested for the presence of water

Observations In columns 3 and 4, record the color and intensity seen. In columns 5 and 6, determine if the substance is an acid or a base, and if the substance is ionic. For the last column, determine which chemical species is acting as an acid or base.

Data Table 1: Acids and Bases Acting in Water
Well	Substance	1drop BTB	Plus 1 drop of substance	Acid or base (Q1)	Ionic? Y/N (Q2)	Species acting as acid or base (Q3)
1	NaHCO3
2	CH3COOH
3	HCL
4	Na2CO3
5	H2SO4
6	CH3COONa
7	NaOH
8	HNO3
9	NaHSO4
10	NH3
11	H3PO4
12	NaH2PO4
13	Na2HPO4
14	Na3PO4
15	NaHSO3

Data Table 2: Following Acid/Base neutralization reactions
Well #	1 Drop of Each	Observation	+2 Drops Acid	Observation	+2 Drops Base	Observation
1	BPB + NaOH		HCl		NaOH
2	BPB + NaOH		H2SO4		NaOH
3	BPB + NaOH		CH3COOH		NaOH
4	BPB + NaOH		H3PO4		NaOH
5	BPB + Ca(OH)2		HCl		Ca(OH)2
6	BPB + Ca(OH)2		H2SO4		Ca(OH)2
7	BPB + Ca(OH)2		CH3COOH		Ca(OH)2
8	BPB + Ca(OH)2		H3PO4		Ca(OH)2
9	BPB + NH3		HCl		NH3
10	BPB + NH3		H2SO4		NH3
11	BPB + NH3		CH3COOH		NH3
12	BPB + NH3		H3PO4		NH3

Please note here if any of the other starting materials is other than a clear, colorless solution.

Data Table 3: Investigating Odor as a Means of Indicating Neutralization.
Substance(s)	Odor
2 Drops of HCl in Well #1
1 Drop of Ammonia on Swab
Swab with Ammonia & HCl

Data Table 4: Investigating Evaporation as a Means of Indicating a Neutralization Reaction.
Reaction Mixture	Observation (When Wet)	Observation (When Dry)
HCl + NaOH
CH3COOH + NH3
HNO3 + NaOH

PART 5: Mini-Experiments

1. Use BTB to classify four household products as acidic or basic. Possible substances to test include home cleaning products, glass cleaner, liquid detergent, bleach, soft drinks, liquid from food items, etc. Remember to:

a. Hypothesis (What you think will happen and why) or purpose:

b. Method used to test your hypothesis:

c. Data and Observations Put your data and observations in the space below. You can include pictures that you âdraw.â

d. Conclusions

2. Find one common, highly colored substance that can be used as an acid-base indicator.

Possible substances include fruit/vegetable juice or products, inks, food coloring, flower

petals, etc. If using fresh fruit, veggies, or flowers, crush the substance with a little water or

rubbing alcohol to extract the colored pigments. If red cabbage is available, it makes a superb

acid-base indicator. Then use a few drops of the colored extract as the indicator. Test four

more household products using the freshly made acid-base indicator. Remember to:

a. State a hypothesis or purpose.

b. State the testing method.

c. Use the prepared indicator to test four substances known to be acids or bases from either the LabPaq or home materials and record results.

d. State conclusions in terms of the hypothesis or purpose.

Questions

A. Review the substances used in Part 1. Determine whether each substance contains an acid or a base based on the BTB results. Place answers to this question in column 6 of Data Table 1.

B. Review the responses to Question 3. The anion that is produced in the dissociation of the compound goes on to react with the water. Identify the anion product in each reaction. Place the formulas for these species into column 7 of Data Table 1. If the substance is not ionic and thus does not dissociate, then list the substance in column 7, just as it appears in column 1.

C. For each ionic species in Data Table 1, write the equation showing the dissociation of the compound in water. Hint: thereâs one for each line provided below.

a. NaHCO3 Ã Na

+ HCO3

Review the responses to Question 3. The anion that is produced in the dissociation of the compound goes on to react with the water. Identify the anion product in each reaction. Place the formulas for these species into column 7 of Data Table 1. If the substance is not ionic and thus does not dissociate, then list the substance in column 7, just as it appears in column 1.

D. Write the reaction of each acid or base the substance listed in column 7 with water.

Acids: Bases:

a) HCO - + H-OH Ã H CO

+ OH-

3 2 3

1. What is produced in each and every reaction of an acid with water?

2. What is produced in each and every reaction of a base with water?

E. Review the results in Data Table 2. For each reaction mixture, write the reaction equation describing the acid/base neutralization reaction:

2) 2NaOH + H2SO4 Ã 2H2O + Na2SO4

F. Define the term âneutralizationâ and provide an example of a neutralization equation. List the three ways used in this lab to detected neutralization.

G. Define the term âsalt,â and provide an example.

H. Review Data Table 3. What happened when the two chemicals were mixed? What indicates that conclusion? What reaction took place?

I. Review Data Table 4. What happened when the solution mixtures on the glass slide were heated? Describe the process that took place.

J. In Part 4, for HCl + NaOH, what is left on the slide after heating? Provide the formula. What is the common name of this substance?

CHEM164 Study Guide - Midterm Guide: Phenylmagnesium Bromide, Gilman Reagent, Aldehyde

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