Chemistry 5th Exam Study

What are organic reactions?

• They are not always balanced (we care more about what we are making rather than how much)

• Sometimes the inorganic byproducts are not written (we mostly care about the organic product)

• For each reaction learned, you want to know the organic reactant(substrate), the inorganic reactants (reagents), and the product(s)… if one of those 3 is missing you can fill it in

• Sometimes reagents are over the arrow, sometimes they are in front of the arrow with the substrate… it doesn’t matter

What are the techniques to solve organic reaction problems?

1. Identify what’s given and what is the question asking for

2. Draw the structure in the format your most comfortable with

3. Identify abd bane type of substrate (example: alkene, alcohol, or etc.) Hint identify the functional group

4. Identify which part of the structure is reacting and which is not reacting. Hint: take special note what carbon is bonded ot the portion that is reacting

5. Identify the type of reactions can occur with your substrate

6. Identify the reagents to determine the reaction

7. Identify and name the type of products produced

8. Number your parent chain

9. Redraw unreacted portion of your structure iast a product

10. Number the parent chain on the product making sure the unreacted substituents are correct

11. Add the correct functional group/atoms to make the correct

What are the four types of organic reactions and their definitions?

• Oxidation: in organic chemistry involves carbon’s gain of bonds to oxygen at the alpha carbon (or the loss of hydrogen from the alpha carbon)

• Reduction: involves carbon’s loss of bonds to oxygen at the alpha carbon(or the gain of hydrogen from the alpha carbon)

• Addition: When you are adding two things to the carbons with a double and or tripled bonds

• Substitution: When you are substituting one thing for another

What is a combustion reaction, and its example?

Combustion reaction of an organic molecule that contains only C, H, and/or O with oxygen gas to produce CO₂ gas and H₂O gas(exothermic)

Organic substrate + O_2(g) + CO_2(g) + H₂O_(g) + heat

Equation for the combustion of methane gas

CH₄ + O₂ → CO_2(g) + H₂O_(g) + heat

or another example:

Propene + O₂ → CO_2(g) + H₂O_(g) + heat

What are reactions of alkanes?

• Besides combustions alkanes will only do substitution reactions

• For substitution of alkane, a H on the substrate will always be substituted

Reaction between an alkane and a diatomic halogen (Br₂ or Cl₂)

reagents X₂ (halogens)

Type of reaction: substitution

• Halogen (X): is substituted in place of a hydrogen on the alkane

• Requires light(hv) or heat

• The products are alkyl halides(R-X)

STUDY IMAGE WITH THE REST OF THE NOTES

What is the reactions of alkenes and alkynes like?

• Besides combustions alkenes will only do addition reaction

Addition reactions:

• When you are adding two things to the carbons with a double and or tripled bonds

STUDY IMAGE WITH THE REST OF THE NOTES

What is the hydrogenation of alkenes and alkynes?

• Type of reaction: addition

• In hydrogenation reactions alkenes and alkynes, the multiple bonds converts to a single bond

• Converting unsaturated organic molecules to saturate organic molecules by

• A catalyst like Pt, Ni, or Pd speeds up the reacion

Substrate: alkene/alkyne (unsaturated), Reagent: hydrogen, Catalyst: either Pt, Ni, or Pd

Type of product: alkane(saturated)

STUDY IMAGE WITH THE REST OF THE NOTES

What is the hydration of alkenes?

1. An alkene breaks its double bond, H and OH is added

2. An acid(example: HCl, H⁺, or etc.) is needed as a catalyst

Hydration of alkenes = addition of an H₂O molecule across a C-C double bond(accoding to Markovnikov’s Rule)

Substrate: alkene, Reagent: H₂O, Catalyst: strong acid, Type of product: alcohol

RMB CARBONS MUST HAVE 3 BONDS, BONDS BETWEEN C AND H ARE NOT SHOWN IN BOND LINE STRUCTURE

What are the major and minor products?

If two carbons of the double bond are attached to different groups(asymmetrical alkene), H adds to the carbon of the double bond with more H directly attached to produce the Major product.

• Markovnikov’s Rule: hydrogen will add carbon on C=C with more “H”(hydrogen)

STUDY PAGE FROM NOTES

What is the reaction of alcohols?

Alcohols can undergo oxidation reactions.

What are oxidation reactions?

Alcohols can be oxidized with a variety of oxidizing agents to form aldehydes and ketones

• Oxidation: in organic chemistry involves alpha carbon’s gain of bonds to oxygen(or loss of hydrogen)

Reagents:

• A common oxidizing reagent is K₂Cr₂O₇ or KMnO₄

• The symbol [O] over the reaction arrow is used to designate any general oxidizing agent.

• Also depends on classification of alcohol, you will end up with a different product!

STUDY PAGES FROM NOTES

What are the reactions of aldehydes and ketones?

Aldehydes undergo oxidation or reduction reactions

Ketones will undergo reduction reactions ONLY

What is reduction (hydration of C=O)?

Reagents H₂ and Pt/Pd/Ni

Hydrogenation(reduction) of aldehydes and ketones is the addition of an H₂ molecule across a carbon-oxygen double bond.

Same reaction as with alkenes, but with a C=O instead of C=C!

Hydrogenation of an aldehyde leads to the formation of a primary alcohol.

Hydrogenation of a ketone leads to the formation of a secondary alcohol

How do we test for aldehydes vs. ketones? (What is the tollens’ test).

An aldehyde is oxidized to a carboxylic acid. Silver also forms. Acetone give a positive or negative result for Tollens test because acetone is a standard ketone.

What are the techniques to solve organic reaction problems?

1. Identify what’s given and what is the question asking for

2. Draw the structure in the format your most comfortable with

3. Identify the name type of substrate (example: alkene, alcohol, or etc,) Hint identify the functional group

4. Identify which part of the structure is reacting and which is not reacting. Hint Take special note what carbon is bonded to the portion that is reacting.

5. Identify types of reactions can occur with your substrate

6. Identify the reagents to determine the reaction

7. Identify and name the type of products produced

8. Number your parent chain

9. Redraw unreacted portion of your structure as a product

10. Number the parent chain ont he product making sure the unreacted substituents are correct

11. Add the correct functional group/atoms to make the correct

What is solubility(what are hydrocarbons, what are the non-polar molecules)?

• Polar substances are more soluble in polar solvents(water, methanol, ethanol, and etc..)

• Non-polar substances are more soluble in non-polar solvents (cyclo-hexane, carbon tetrachloride, and etc.)

Hydrocarbons are very non-polar. Hydrocarbons are more soluble in non-polar solvents.

• Alkanes, alkenes, alkynes, and aromatics

*KNOW THAT BENZENE IS NON-POLAR

Are ethers, thiols. 3° amines polar or non-polar, and what is it more soluble in?

Ethers, Thiols, 3° amines are polar. Ethers, Thiols, 3° amines are more soluble in polar solvents.

What are compounds containing carbonyl group(are they polar or non-polar)?

Compounds containing carbonyl group are very polar. Group containing carbonyl are more soluble in polar solvents.

STUDY PICTURE OF THEIR DIFFERENCES

What are compounds that can hydrogen bond with polar solvents like, and where are they most soluble in?

Compounds that can Hydrogen bond with polar solvents are very polar. Compounds that can hydrogen bond with polar solvents are the most soluble in polar solvents.

• 1° and 2° amines, 1° and 2° amides, alcohols, and carboxylic acids all can hydrogen bond

What are london dispersion forces(what has it, its strength, surface area (STUDY FROM NOTES), and size effects on strength of London forces?

• What has it: All matter has this

• Strength: very very weak

• Size effects on Strength of London forces: larger more electrons (e-), larger your(carbon chain) hydrocarbon more e- therefore stronger LDF

• butane vs < decane

What has dipole dipole forces(attraction)?

• What has it: polar compounds

• Strength: medium weak

• Polarity effects on strength of dipole dipole attractions, more polar compound, stronger dipole-dipole

What is the hydrogen bonding attraction(what has it, and strength)?

• What has it: polar compounds that has an O-H, N-H, F-H

• H-O > H-N

What are the characteristics of carbohydrates?

Source of carbohydrates: PLANTS

Plants by chlorophyll

CO₂ and H₂O react to give different carbohydrates through a complex series of reactions called photosynthesis.

nCO₂ + nH₂O → light/chlorophyll → (CH₂O)_n + nO₂

What are the three different types of carbohydrates?

• Monosaccharides: 1 sugar or monomer

• Disaccharides: 2 sugars

• Polysaccharides: many sugars bonded together

STUDY PICTURES IN NOTES

What are characteristics of polymers?

• Large, long chain molecules composed of repeating structural units = monomers

• Polymers can be composed of several thousand monomers

• Found in nature including cellulose in plants, starches in food, proteins, and DNA in the body

• There are also synthesis (man-made) polymers like T eflon and nylon

• Monomers: small molecules that can link together in some repeating way.

What are the different functional groups?

• A monosaccharide with a ketone group is a ketose

• An aldose is a monosaccharide that contains and aldehyde group.

STUDY IMAGES FROM NOTES

What are the names of the number of chain lengths?

• A three-carbon monosaccharide is a triose

• A four-carbon monosaccharide is a tetrose

• A five-carbon chain sugar is a pentose

• A six carbon chain is a hexose

• A seven carbon chain is a heptose

• a 8 carbon chain is an octose

REVIEW THE NOTES FOR STRUCTURES

What is stereochemistry(D vs. L) isomers? What is a Fischer projection?

• By convention, it is the position of the hydroxyl (-OH) group bonded to the penultimate (next to last) carbono or the last chiral carbon that determines the monosaccharide D or L.

For a properly drawn Fischer projection:

• If the -OH group is pointing right = D

• If the -OH group is pointing left = L

What are stereoisomers?

• Stereoisomers: are pairs of molecules that have the same molecular formula and the same bonding pattern, but different arrangements of the atoms in spsce

• cis and trans are one type of stereoisomer

• D or L refer to a different type of stereoisomer

What are chiral objects like?

Chiral objects have an image and a mirror image that are not the same ( contain a chiral carbon)

1. When the chiral objects are sliced in half, the two halves are not the same.

What are achiral objects?

Achiral objects do not have a unique image and mirror image(don’t contain a chiral carbon)

1. When achiral objects are sliced in half, the two halves are identical (super imposable)

What are chiral carbons?

Chiral carbons are tetrahedral carbons with four different attachments

• These two molecules are not superimposable: they are stereoisomers

* KNOW THAT AS LONG AS IT HAS AT LEAST ONE CHIRAL CARBON, THE COMPOUND IS CHIRAL

What are enantiomers?

• Two stereoisomers that are nonsuperimposable mirror images of one another are called a pair of enantiomers(a specific type of stereoisomer)

• An enantiomer is the mirror image of a chiral compound

What carbohydrates are chiral?

• Ex: glyceraldehyde comes in to versions(isomers)

• L-glyceraldehyde

• D-aldehyde

• The first carbon is the carbon on the top(carbonyl has priority over hydroxyl in numbering)

• L-version, the OH on the last chiral carbon is on the left

• D-version, the OH on the last chiral carbon is on the right

What are the most important monosaccharides?

glucose, fructose, and ribose

STUDY THE STRUCTURES

What are cyclic structures?

• Monosaccharides that can be in open-chain form and in a cyclic form(Haworth projections)

What are anomers alpha and beta notation?

• In the alpha anomer: the hydroxyl group points down (alpha = “OH down” in a proper Haworth projection)

• In the beta anomer: the hydroxyl group points up (beta = “OH up” in a proper Haworth projection)

What are 5-member rings always going to be?

• Ketohexose or aldopentose

What are the types of disaccharides?

Carbohydrates composed of 2 monosaccharide units held together by a bond called glycosidic linkage (special name for ester linkage between 2 monosaccharides)

What are alpha and beta linkages?

There are different types of linkages in disaccharides

1. In alpha-linkages, the bond from the alpha carbon of the first sugar to the oxygen is pointing down (we’re removing H₂O(H & OH) )

• dehydration reaction link biomolecules

STUDY PICTURES ON NOTES

2. In beta-linkages, the bond from the alpha carbon of the first sugar to the oxygen is pointing upwards

What are the two most important disaccharides?

• glucose + glucose → maltose

• glucose + fructose → sucrose

What is hydrolysis of disaccharides?

Water and a strong acid will break the glycosidic linkage

REVIEW PICTURES IN NOTES

What are polysaccharides?

• Polysaccharides are high molecular weight polymers of monosaccharides linked together through glycosidic bonds

What is a starch?

Polymer of sugars, how living things stores glucose

What is cellulose?

A structural material for plants