Organic Chemistry Flashcards

Question

Explain an aldol condensation reaction

Answer 1

Two aldehyde's react with an alcohol to combine together to form an aldol. If the aldol is heated, the molecule will undergo elimination and will loose the alcohol to produce a water

Answer 2

Method of forming C=C double bonds by converting aldehydes and keytones into alkenes (C=O becomes C=C) - First step: phosphonium salt from the SN2 rxn of an alkyl halide with the nucleophile triphenylphosphine (C6H5)3P. The phosphonium salt is then deprotonated with a strong base, yeilding a neutral ylide or phosphorane

Answer 3

Halogenation adds a halogen to the aromatic ring with bromine or chlorine in the presence of a lewis acid, such as FeCl3, FeBr3 or AlCl3

Answer 4

Ring reacts with fuming sulfuric acid (a misxture of sulfuric acid and sulfur trioxide) to form sulfonic acids

Answer 5

A mixture of nitric and sulfuric acids is used to create the nitronium ion, NO2+, a strong electrophile. This reacts with aromatic rings to produce nitro compounds

Answer 6

A carbocation electrophile, usually an acyl group, is incoporated into the aromatic ring. These reactions are usually catalyzed by Lewis acids such as AlCl3. This reaction can also be used to add alkyl groups, but the reaction is difficult to control and can lead to multiple products

Answer 7

**_1. Activating (ortho/para - directing Substituent)_** - Electron Donating NH2 \> NR2 \> OH \> NHCOR \> OR \> OCOR \> R **_2. Deactivating (ortho/para - directing Substituent)_** - Weakly Electron withdrawing F \> Cl \> Br \> I **_3. Deactivating, Meta-directing substituents_** - Electron withdrwing NO2 \> SO3H \> carbonyl compounds, including COOH, COOR, COR, and CHO

Answer 8

Ring can be reduced by catalytic hydrogenation under vigorous conditions (elevated temperature and pressure) to yeild cyclohexane. Ruthenium or rhodium on carbon are the most common catalysts; platinum or palladium may also be used

Answer 9

Phenols may be synthesized from arylsulfonic acids with heat and NaOH. However, this reaction is useful only for phenol or its alkylated derivatives, as most functional groups are destroyed by the harsh reaction conditions - A more versatile method of synthesizing phenols proceeds using hydrolysis of diazonium salts

Answer 10

Alcohols can be dehydrated in strongly acidic solutions (usually H2SO4) to produce alkenes. The mechanism of this dehydration reaction is E1, and proceeds by first protonating the alcohol and then removing the water molecule to form the double bond \*Two products normally produced, major and minor based on their subsititution

Answer 11

CH2OH side chain on a cyclic ring, turned into COOH using CrO3, H2SO4 in acetone

Answer 12

Produce compounds called quinones (2,5 - cyclohexadiene-1,4diones

Answer 13

Produces asymmetrical ethers from the reaction of metal alkoxide ions with primary alkyl halides or tosylates The alkoxides behave as nucleophiles and displace the halide or tosylate in an SN2 reaction, producing an ether \*\*Williamson ether synthesis can also be applied to phenols. Relatively mild reaction conditions are sufficient, due to the acidity of phenols

Answer 14

Cyclic ethers, oxiranes, are prepared in a number of ways. They can be synthesized by means of an internal SN2 displacement. Since the nucleophile and sustrate are part of the same molecule, they are in close proximity, facilitating the reaction

Answer 15

Will produce an oxirane

Answer 16

Cleavage will take place only under vigorous conditions: high temperature in the presence of HBr or HI * Initiated by protonation of the ether oxygen * RxN proceeds via SN1 or SN2 mechanism, depending on the condition and the structure of the ether * usually producing an alkyl halide and an alcohol

Answer 17

Reactions of epoxides provide additional insight into SN1 and SN2 reaction mechanisms. * Base-catalyzed cleavage of epoxides has the most SN2 character, so it occurs at the least hindered (least substituted) carbon. The basic environment provides the strong nucleophile required for SN2 reactions * Acid-catalyzed cleavage is thought to have some SN1 character as well as some SN2 character. The epoxide oxygen can be protonated, making it better leaving group. this give the carbons partial positive charges. Since substitution stabilizes this charge (tertiary carbson provide the most stable carbocations), the most substututed C becomes a good target for nuceophilic attack

Answer 18

Acetic Acid

Answer 19

Formic Acid

Answer 20

* Carboxylic acids can be prepared via oxidation of aldehydes, primary alcohols, and certain alkylbenzenes. Any strong oxidizing agent, including KMnO4, K2Cr2O7, and CrO3, will create a carboxylic acid. * A primary alcohol can also be oxidized first with PCC to create an aldehyde and then further oxidized with Tollen's reagent to create the carboxylic acid

Answer 21

KMnO4, OH-, heat are used first then H+ to cleave the double bond and produce carboxylic acids

Answer 22

Such as Grignard reagents, react with carbon dioxide (CO2) to form carboxylic acids. This reaction is useful for the conversion of tertiary alkyl halides into carboxylic acids, which cannot be accomplished through other methods. Note that this reaction adds one carbon atom to the chain \*\*Top row of image

Answer 23

Strong nucleophile Cyanide anion and will displace primary and secondary halides in typical SN2 fashion

Answer 24

Starting with an alkyl halide, a carboxylic acid can be produced by replacing the halide with a cyanide anion and then reacting with water to change the cyanide anion into -COOH

Answer 25

Nucleophile attacks the carbonyl group, carbonyl group reforms and kicks out a leaving group

Answer 26

Nucleophilic substitution is where the C=O bond reformes and there is an elimination of a leaving group

Answer 27

* Carboxylic acids can be reduced with lithium aluminum hydride (LAH) to their corresponding primary alcohols. * Aldehyde intermediates that may be formed in the course of the reaction with LAH are also reduced to their primary alcohol * The reaction occurs by nucleophilic addition of hydride (the H- ion) to the carbonyl group and elimination of water as a leaving group

Answer 28

*_\*\*Need to keep water out of the reaction to make an ester or will reform carboxylic acid\*\*_* * Carboxylic acids react with alcohols under acidic conditions, the oxygen on the carbonyl group can become protonated. This increases the polarity of the C=O bond, putting even more positive charge on the carbon and making it even more susceptible to nucleophilic attack * Again, water is eliminated as a leaving group, and the carbonyl re-forms * this condensation reaction occurs most rapidly with primary alcohols.

Answer 29

* Acyl halides = acid halides * Compounds with carbonyl groups bonded to halides * Several different reagents can accomplish this transformation; thionyl chloride, SOCl2, is the most common * Acid chlorides are very reactive, as the greater electron-withdrawing power of the Cl- makes the carbonyl carbon more susceptible to nucleophilic attack than the carbonyl carbon of the carboxylic acid. (Cl- also good LG)

Answer 30

* Carboxylic acids can undergo decarboxylation reactions, resulting in the loss of carbon dioxide and thus loss of the entire carboxyl group * The carboxyl group is lost and replaced with a hydrogen. * The reaction proceeds through a six-membered ring transition state. * The enol initially formed tautomerizes to the more stable keto form as the final product

Answer 31

Polar heads face outward, where they can be solvated by water molecules, and the nonpolar hydrocarbon chains are inside the sphere, protected from the solvent

Answer 32

A long-chain hydrocarbon with a highly polar end. Generally, this polar end or head is a salt of a carboxylic acid (with sodium ususally)

Answer 33

acetyl chloride or ethanoyl chloride

Answer 34

Benzoyl chloride

Answer 35

Acyl halides are less polar than comparable carboxylic acids, and demonstrate significantly lower melting and boiling points

Answer 36

\*\* Strong carbon nucleophiles\*\*

Answer 37

\*\* Ring generating reaction \*\*

Answer 38

Begins with the attack of the nucleophile

Answer 39

Reacts with water to form the carboxylic acid

Answer 40

* The most common acyl halides are the acid chlorides, although acid bromides and iodides are occasionally encountered. * Acyl chlorides are prepared by reactions of a carboxylic acid with thionyl chlorides, SOCl2, producing SO2 and HCl as side products. * Alternately, PCl3 or PCl5 (or PBr3 to make acid bromide) can be used for this synthesis

Answer 41

Halogen makes a strong electron-withdrawing group, making the carbonyl carbon more susceptible to nucleophilic attack than the carbonyl carbon of the carbonxylic acid. * Since halides are great LGs, nucleophilic attack will always be followed by re-formation of the carbonyl. * Therefore, acyl halides readily undergo nucleophilic substitution reactions, including hydrolysis (with H2O as nucleophile), which produces the origional carboxylic acid.

Answer 42

* Simplest reaction of acid halides is their conversion back to carboxylic acids by classic nucleophilic attack * Acyl halides react very rapidly with water to form their corresponding acid, along with HCL, which is responsible for their irritating odor

Answer 43

* Reaction of an acyl chloride with a carboxylate salt will produce an anhydride through nucleophilic attack and re-formation of the carbonyl

Answer 44

* Acyl halides can be converted into esters by reaction with alcohols. * The same type of nucleophilic attack found in hydrolysis leads to the formation of a tetrahedral intermediate, with the hydroxyl oxygen of the alcohol acting as the nucleophile * Chloride is displaced as the carbonyl re-forms, and the HCL is released as a side-product

Answer 45

* Nucleophilic substitution with amines * An amine, such as ammonia, attacks the carbonyl group, displacing chloride. * The side product is ammonium chloride, formed from excess ammonia and HCL. * Primary and secondary amines can also be used as nucleophile to create N-substituted amides

Answer 46

* Aromatic rings can be acylated in a Friedel-Crafts reaction. * the mechanism is electrophilic aromatic substitution, and the attacking reagent is an acylium ion, formed by reaction of an acid chloride with AlCl3 or another Lewis acid. * The product is an alkyl aryl ketone

Answer 47

* Reduced to alcohol with a strong reducing agent such as LAH * Can also be selectively reduced to the intermediate aldehydes by catalytic hydrogenation in the presence of a "poison" such as quinoline, (AKA. Lindlar's catalyst).

Answer 48

acetic anhydride No longer have -OH groups and therefore cannot form hydrogen bonds

Answer 49

* Anhydrides can be readily synthesized by reaction of an acyl chloride with a carboxylate salt. this is the most effectient and most commonly used method of anhydride synthesis

Answer 50

* Certain cyclic anhydrides can be formed simply by heating carboxylic acids. The reaction is driven by the increased stability of the newly formed ring; hence, only five- and six- membered ring anhydrides are easily made. * In this case, the hydroxyl of one - COOH group acts as a nucleophile, attacking the carbonyl on the other -COOH group and releasing water

Answer 51

* Two carboxylic acid molecules can condense to form an anhydride in a reaction releasing water; however, this reaction requires anhydrous conditions. * Therefore a dehydrating reagent that will remove the water produced in the reaction is neeeded to prevent immediate conversion back to the carboxylic acid * Reagents such as acetic anhydride, trifluoroacetic anhydride, phosphorus pentachloride, or dicyclohexylcarbodiimide (DCC) can be used for this purpose

Answer 52

* Anhydrides are converted into carboxylic acids when exposed to water * Note that in this reaction, the leaving group is actually a carboxylic acid; because the anhydride is symmetrical, it produces two molecules of the same carboxylic acid

Answer 53

* Anhydrides are cleaved by ammonia, producing an amide and a carboxylic acid. * The carboxylic acid then further reacts with ammonia to form an ammonium carboxylate

Answer 54

Anhydride + alcohol = ester + carboxylic acid * Anhydrides react with alcohols to form esters; a single anhydride molecule will produce one ester and also one molecule of carboxylic acid

Answer 55

* Friedel-Crafts acylation occurs readily with anhydrides in the presence of AlCl3 or other Lewis acid catalysts. * This reaction produces an aryl ketone and a carboxylic acid

Answer 56

Acid chloride + alcohol ---(anhydrous conditions)--\> ester + HCl * Esters can be readily obtained from the reaction of acide chlorides with alcohols under anhydrous conditions * Phenolic (aromatic) esters are produced in the same way, although the aromatic acid chlorides are less reactive than aliphatic acid chlorides, requiring base to be added as a catalyst

Answer 57

Carboxylic acid + alcohol -(anhydrous condition)-\> ester + H2O * Mixtures of carboxylic acids and alcohols will condense into esters under anhydrous conditions, liberating water. * use of sulfuric acid as a catalyst and dehydration reagent will drive the reaction forward

Answer 58

Ester -\> carboxylic acid + alcohol * Esters, like the other derivatives of carboxylic acids, can be hydrolyzed, yeilding carboxylic acids and alcohols. * Hydrolysis can take place under either acidic or basic conditions. * Acidic conditions, the first step is protonation of the carbonyl oxygen, followed by water attacking the carbonyl carbon * Basic conditions, the nucleophile (OH-) directly attack the carbonyl carbon.

Answer 59

Ester + ammonia -\> amide + alcohol * Nitrogen bases, such as ammonia, act as a nucleophile and attack the electrophilic cerbonyl carbon atom, displacing the ester functional group to yeild an amide and an alcohol side product

Answer 60

Ester + alcohol -\> New ester + new alcohol * Alcohols can act as nucleophiles and displace the alkoxy groups on esters. * This process, which transforms one ster into another, is called transesterification

Answer 61

* Grignard reagents add to the carbonyl groups of esters to form ketones; however, these ketones are more reactive than the initial esters are are readily attacked by more Grignard reagent. * Two equivalents of Grignard reagent can thus be used to produce tertiary alcohols with good yeild. * The intermediate ketone can be isolated only if the alkyl groups are sufficiently bulky to prevent further attack. * This reaction proceeds via nucleophilic substitution followed by nucleophilic addition

Answer 62

* Important reaction of esters is the **Claisen condensation.** * In the simplest case, two moles of ethyl acetate react under basic conditions to produce a beta-keto ester, ethyl 3-oxobutanoate, which is also known by its common name, acetoacetic ester. * Also known as **acetoacetic ester condensation** * The reaction proceeds by addition of an enolate anion to the carbonyl group of an ester, followed by displacement of ethoxide ion.

Answer 63

* Esters may be reduced to primary alcohols with LAH, but not with NaBH4. * This allows for selective reduction in molecules with multiple functional groups * Note that different alcohols are produced from the ester alkoxy functional group and the carbonyl-containing carbon chain

Answer 64

* Acyl halides can be readily converted into amides by nucleophilic substitution with amines * An amine such as ammonia attacks the carbonyl group, displacing chloride * The side product is ammonium Chloride, formed from excess ammonia and HCL. * Primary and secondary amines cnan also be used as the nucleophile to create substituted amides; tertiary amines are not able to lose a hydrogen and thus cannot participate in this reaction

Answer 65

Ammonia + anhydride -\> amide + carboxylic acid (goes to ammonium carboxylate) * Anhydrides are cleaved by ammonia, producing an amide and a carboxylic acid * The carboxylic acid then further reacts with ammonia to form ammonium carboxylate

Answer 66

ester + amimonia -\> amide + alcohol * Nitrogen bases such as ammonia act as nucleophiles and will attack the electrophilic carbonyl carbon atom, displacing the ester functional group to yeild an amide and an alcohol side-product

Answer 67

water + amide --(acidic condition)--\> carboxylic acid + ammonia * Amides can be hydrolyzed under acidic conditions, via nucleophilic substitution, to produce carboxylic acids. * Under basic conditions amides react to form carboxylates

Answer 68

* The Hofmann rearrangement converts amides to primary amines with the loss of the carbonyl carbon as a molecule of CO2 * The mechanism involves the formation of a nitrene, the nitrogen analog of a carbene * The nitrene is attached to the carbonyl group and rearranges to form an isocyanate, which under aqueous reaction conditions is hydrolyzed to the amine

Answer 69

Amide --(LAH)--\> amine * Amides can be reduced with LAH to the corresponding amine. Notice that this differes from the product of the Hofmann rearrangement in that no carbon atom is lost * Note that, unlike with a carboxylic acid reduction with LAH, the oxygen atom is completely removed

Answer 70

Picture #1

Answer 71

Formula, IUPAC, COmmon Name Class of compound; characteristics

Answer 72

* Alkyl halides react with ammonia to produce alkylammonium halide salts. * Ammonia functions as a nucleophile and displaces the halide atom * When the salt is treated with base, the alkylamine product is formed

Answer 73

* The preferred method for synthesizing amines is the Gabriel synthesis * The pathway converts a primary alkyl halide to a primary amine without uncontrolled additional reactions seen in the direct alkylation of amines * The first step is the creation of phthalimide, a nitrogen source based on ammonia, but with more controlled reactivity

Answer 74

* Amines can be obtained from other nitrogen-containing functionalities through reduction reactions using typical reducing agents * Four different types: * From nitro compounds * From nitriles * Form imines * From amides

Answer 75

* Nitro compounds are easily reduced to primary amines * The most common reducing agent is iron or zinc and dilute hydrochloric acid, although many other reagents can be used. * This reaction is especially useful for aromatic compounds, because aromatic rigs are readily nitrated and thus provide an efficient route for amine synthesis

Answer 76

* Nitriles can be reduced with hydrogen and a catalyst, or with lithium aluminum hydride (LAH) to produce primary amines

Answer 77

* Amines can be synteized by reductive amination: a process in which an aldehyde or ketone is reacted with ammonia, a primary amine, or a secondary amine to form a primary, secondary, or tertiary amine, respecitvely. * When the amine reacts with the aldehyde or the ketone, an imine intermediate is produced. * similar to a crbonyl, the imine can then undergo hydride reduction. when the imine is reduced with hydrogen in the presence of a catalyst, an amine is produced

Answer 78

Amides can be reduced with LAH to form amines

Answer 79

* Exhaustive methylation is known as Hofmann elimination * In this process, an amine is converted to a quaternary ammonium iodide salt by reacting with excess methyl iodide * Treatment with silver oxide and water converts this to the ammonium hydroxide, which, when heated, undergoes elimination to form an alkene and an amine. * The predominant alkene formed is the least substituted, in contrast with normal elimination reactions, where the predominant alkene product is the most substituted

Answer 80

Weak nucleophile

Answer 81

see attached

Organic Chemistry Flashcards

(109 cards)