Grade 11Organic Chemistry

why substitution reactions occur only in saturated hydrocarbons and addition reaction in unsaturated????

Ranjita yadav

14 Years agoGrade 11

3 Answers

nikhil arora

Approved Tutor Answer14 Years ago

Hi Ranjita,

In saturated compounds all carbons are attached through 4 single bonds, which means there is no space to add another substituent , if they undergo addition that would mean a particular carbon will be having 5 single bonds which is not desirable. They can only replace one of their groups with a new one. thats why they always undergo substitution.

Unsaturated compounds have some carbons attached through double or triple bonds. In case of alkenes, C=C double bond may be converted to C-C single bond and carbon would become on substituent short, hence they can add a new substituent which is called addition. similar is the case with alkynes.

G Narayana Raju

Approved Tutor Answer14 Years ago

unsaturated hydrocarbons are highly reactive so the try break their double/triple bond to lower bonds by addition reactions.

where as in saturated hydrocarbons they are not much reactable so the go for substitution reactions.

Ghanshyam Khandelwal

9 Years ago

Saturated hydrocarbons are quite unreactive.being unreactive, saturated hydrocarbon do not react with many substances. Saturated hydrocarbon, however, react with chlorine in presence of sunlight. If the substitution substitution of hydrogen atoms takes place by chlorin, it is also called chlorination.

Substitution reaction of methane with chlorine :

$CH_{4} + CL_{2} \rightarrow CH_{3}CL + HCL$

In this reaction, one H atom of methane has been substituted by a Cl atom, converting CH₄into CH₃CL ( chloromethane). By supplying more chlorine, it is possible to replace all the hydrogen atoms of methane by chlorine,one by one