Chemical reactions of the alkanes Flashcards
Why are alkanes generally unreactive?
Alkanes do not react with most common reagents due to:
- Strong C—C and C—H bonds
- Non-polar C—C bonds
- Similar electronegativity of carbon and hydrogen
What is the primary reaction that alkanes undergo with oxygen?
Combustion
What are the products of the complete combustion of alkanes?
Carbon dioxide and water
What is the equation for the complete combustion of methane?
CH₄(g) + 2O₂(g) → CO₂(g) + 2H₂O(l)
What happens during incomplete combustion of alkanes?
Inadequate oxygen leads to the formation of carbon monoxide (CO) or soot (C) instead of complete combustion products
What is a key indicator that incomplete combustion has occurred?
Formation of carbon monoxide or soot
What initiates the reaction of alkanes with halogens?
Sunlight provides high-energy ultraviolet (UV) radiation
What type of reaction occurs when alkanes react with halogens?
Substitution reaction
What is the first step in the mechanism for bromination of methane?
Initiation: Breaking of the Br—Br bond by homolytic fission
What is formed during the initiation stage of the bromination of methane?
Bromine radicals
What occurs during the propagation step of the bromination mechanism?
Bromine radicals react with methane, forming methyl radicals and hydrogen bromide
What is the result of the termination step in the bromination mechanism?
Formation of a molecule with all paired electrons, stopping the reaction
What can limit the importance of radical substitution in organic synthesis?
Further substitution and formation of a mixture of products
What is a consequence of further substitution in haloalkane synthesis?
Formation of multiple bromo compounds (e.g., CH₃Br, CH₂Br₂, CHBr₃, CBr₄)
How does the position of substitution affect the products formed from longer carbon chains?
Mixtures of monosubstituted isomers can be formed by substitution at different positions
Fill in the blank: The complete combustion of any alkane produces _______.
carbon dioxide and water
True or False: Methane can react explosively with fluorine.
True
