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How can the organic compounds like alkanes,alkenes,alkynes be prepared in labs ? What will be the temperature required to prepare them ??

How can the organic compounds like alkanes,alkenes,alkynes be prepared in labs ? What will be the temperature required to prepare them ??

Grade:12

1 Answers

SAGAR SINGH - IIT DELHI
878 Points
13 years ago

Dear student,

General Methods of Preparation of Alkanes

(i)   Decarboxylation :

(a)    Decarboxylation means removal of CO2 from molecules having - COOH gp.

(b)    Saturated monocarboxylic acid salt of sodium potassium on dry distillation with soda lime gives alkane.

                                 RCOONa soda-lime  R-H

or                  RCOONa + NaOH cao  R-H + Na2CO3

(c)    The alkane formed always contains one carbon atom less than the original acid.

(d)    The yield is good in case of lower members but poor for higher members.

(e)    Soda lime is prepared by soaking quick lime CaO in caustic soda solution and then drying the products. It is generally written as NaOH + CaO. Its reaction is milder than caustic soda. Otherwise the reaction will occur violently. Also CaO used alongwith NaOH keeps it dry (NaOH is hygroscopic) to aid fusion.

(f)        The decarboxylation of sodium formate yields H2.

                                        HCOONa + NaOH cao H2 + Na2CO3

                                         CH3COONa + NaOH cao CH4 + Na2CO3

                                                                methane

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All the best.

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Askiitians Expert

Sagar Singh

B.Tech, IIT Delhi

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