Alkyne Synthesis and Dihalides Concepts

Professor Dave explains the synthesis of alkynes using E2 reactions, focusing on vicinal and geminal dihalides. He discusses the use of strong bases like sodamide and the importance of excess base for geminal dihalides. The video also covers the formation and reactions of acetylide ions, including SN2 reactions with alkyl halides.

What is the primary reaction type used in synthesizing alkynes from dihalides?

• SN2 reaction

• E1 reaction

• E2 reaction

• SN1 reaction

What is a vicinal dihalide?

• Two halogens on the same carbon

• Two halogens on adjacent carbons

• Two halogens on opposite ends of a molecule

• Two halogens on non-adjacent carbons

Which base is used for the dehydrohalogenation process in alkyne synthesis?

• Lithium diisopropylamide

• Potassium tert-butoxide

• Sodamide

• Sodium hydroxide

Why are certain protons more acidic in the context of alkyne formation?

• They are part of a larger molecule

• They are attached to carbons with partial positive charges

• They are attached to a more electronegative atom

• They are closer to a double bond

What is the geometry of carbons involved in a triple bond?

• Tetrahedral

• Linear

• Trigonal planar

• Bent

What distinguishes a geminal dihalide from a vicinal dihalide?

• Geminal dihalides have halogens on opposite ends of a molecule

• Geminal dihalides have halogens on adjacent carbons

• Geminal dihalides have halogens on the same carbon

• Geminal dihalides have halogens on non-adjacent carbons

Why is excess base required in the synthesis of alkynes from geminal dihalides?

• To prevent side reactions

• To ensure complete reaction of all molecules

• To decrease the reaction time

• To increase the reaction temperature

What is the role of the acetylide ion in alkyne synthesis?

• It increases the acidity of the solution

• It acts as a catalyst

• It serves as a nucleophile

• It stabilizes the reaction intermediate

What type of reaction can an acetylide ion undergo with an alkyl halide?

• E2 reaction

• SN1 reaction

• SN2 reaction

• E1 reaction

What is a potential outcome of reacting an acetylide ion with an alkyl halide?

• Formation of a geminal dihalide

• Formation of a terminal alkene

• Formation of a vicinal dihalide

• Formation of a fully substituted alkyne