Ch. 9 - Alkenes and AlkynesSee all chapters
All Chapters
Ch. 1 - A Review of General Chemistry
Ch. 2 - Molecular Representations
Ch. 3 - Acids and Bases
Ch. 4 - Alkanes and Cycloalkanes
Ch. 5 - Chirality
Ch. 6 - Thermodynamics and Kinetics
Ch. 7 - Substitution Reactions
Ch. 8 - Elimination Reactions
Ch. 9 - Alkenes and Alkynes
Ch. 10 - Addition Reactions
Ch. 11 - Radical Reactions
Ch. 12 - Alcohols, Ethers, Epoxides and Thiols
Ch. 13 - Alcohols and Carbonyl Compounds
Ch. 14 - Synthetic Techniques
Ch. 15 - Analytical Techniques: IR, NMR, Mass Spect
Ch. 16 - Conjugated Systems
Ch. 17 - Aromaticity
Ch. 18 - Reactions of Aromatics: EAS and Beyond
Ch. 19 - Aldehydes and Ketones: Nucleophilic Addition
Ch. 20 - Carboxylic Acid Derivatives: NAS
Ch. 21 - Enolate Chemistry: Reactions at the Alpha-Carbon
Ch. 22 - Condensation Chemistry
Ch. 23 - Amines
Ch. 24 - Carbohydrates
Ch. 25 - Phenols
Ch. 26 - Amino Acids, Peptides, and Proteins

Hydrogenation reactions are a subtype of reduction reactions that add hydrogens to double and triple bonds. These differ in the types of products made and the stereochemistry of the mechanism.  

Concept #1: The definition of hydrogenation.

Concept #2: Using Catalytic hydrogenation or Wilkinson’s Catalyst to turn alkynes to alkanes. 

Catalytic Hydrogenation or Wilkinson’s Catalyst: Alkane products

Stereochemistry: Syn Addition

Concept #3: Using Dissolving Metal Reduction or Lindlar’s Catalyst to turn alkynes to alkenes.

Dissolving Metal Reduction: Alkene products

Stereochemistry: Anti Addition

Lindlar’s Catalyst: Alkene products

Stereochemistry: Syn Addition

Practice: Predict the product of the multistep synthesis

Additional Problems
Provide the reagents required for the following transformations. Note, that some of these methods will require more than one chemical step. All the steps and reagents must be included.
Provide an efficient multistep synthesis for the conversion of the given starting material into the target molecule shown to the right. You must begin with the given starting organic compound. Each C that ends up in the target compound must come from the given starting organic compound. For each functional group transformation, give all necessary reagents, solvents, and catalysts; give a structural formula for each organic reactant and the major organic product(s). Show stereochemistry appropriately when necessary. If a mixture of products (for example a mixture of stereoisomers) must be present after a step, assume that you can separate the mixture and take the one needed product forward through the next step.
Reaction of 3,4,5-trimethyl-4-hexen-1-yne with H2 and Pd will produce which of the following compounds? A) 2,3,4-trimethylhexane B) 3,4,5-trimethylhexane C) 2,3,4-trimethyl-1-hexene D) 3,4,5-trimethyl-1-hexyne E) 2,3,4-trimethyl-5-hexyne
What is the major product of the reaction drawn below?
Predict the product for the reaction below.   
The reduction of an alkyne can be made to stop at the alkene stage through the use of special reagents. 
Fill in the box with the product(s) that are missing from the chemical reaction equation. Draw only the predominant regioisomer product or products (i.e. Markovnikov or non-Markovnikov products) and please remember that you must draw the structures of all the product stereoisomers using wedges and dashes to indicate stereochemistry. When a racemic mixture is formed, you must write "racemic" under both structures EVEN THOUGH YOU DREW BOTH STRUCTURES.
Consider the strucutres below and answer the following questions.  g. Which compound(s) cannot be prepared by the appropriate reduction of an alkyne? 
For the reaction shown, select the expected major organic product.
Give all possible product/products and designate stereoselectivity &/or regioselectivity by using wedges and dashes.   
Give all possible product/products and designate stereoselectivity &/or regioselectivity by using wedges and dashes.   
Give all possible product/products and designate stereoselectivity &/or regioselectivity by using wedges and dashes.   
Reduction of a triple bond to an E (trans) double bond can be accomplished with which set of reagents?  
Predict the missing structures of products or reagents that you may use to accomplish the following transformations. Show the source of incorporation of deuterium and the stereochemistry when appropriate (No mechanism is required).
For the following reaction, the resulting stereochemistry of the expected product is best described as:
Identify which of the reagents would NOT produce cis-3-hexene from 3-hexyne. If it helps, draw out the reaction. After choosing the reagent that would not work indicate why and draw out its product and name it :).    I. H2, Pd/BaSO4 II. H2/Ni2B III. Na, NH3 (liq)
Supply the reagents needed to perform the following transformation:
Predict the organic product(s) for the following reaction. Be sure to indicate stereochemistry when appropriate, if stereoisomers are produced draw one and state the relationship between the other stereoisomer formed. (enantiomers, diastereomers, etc.).
Supply the reagent(s):
Supply the structure of the product
Draw the major organic product for each of the following hydrogenation reactions. Indicate which stereoisomer is formed if more than one is possible.
What is the product of the following reaction? 
Draw the product of the hydrogenation of 2-butyne with Lindlar catalyst. Draw all hydrogen atoms.
What reagent is required to accomplish the following transformation? a. H2, Ni b. H2 catalyst c. Na, NH3 d. H2, Pd-C
Predict the product(s) of treating the given alkyne with the reagents shown below. Show ALL atoms on chirality (stereo) centers, using wedge-and-dash bonds to indicate stereochemistry.
Draw the alkyne you would start with if you wanted to synthesize 1-hexene.
Predict the products for each of the following reactions:
Draw the product of the following reaction. 
Alkynes are reduced by lithium dissolved in liquid ammonia. For the reaction below, draw a structure for the major organic product of the reaction. Consider E/Z stereochemistry of alkenes.
Draw the product of the hydrogenation of 2-butyne. Draw all hydrogen atoms.  
Which is the major product of the reaction provided? 
Draw the structure of the product that is formed when the compound shown below is treated with the following reagents: 1) Na, NH3(liq); 2) D2, Pd, including its relative stereochemistry.
What is the major organic product obtained from the following reaction?
Wilkinson's catalyst accomplishes which of the listed molecular syntheses?A. syn addition of H2 to an alkeneB. anti addition of H2 to an alkeneC. syn dihydroxylation an alkeneD. anti dihydroxylation an alkene 
A compound, C6H10, which reacts with 2 mol of hydrogen over a platinum catalyst and which gives a precipitate with Ag(NH3)2+ could be: a. Ib. Vc. IId. IIIe. IV