Log out Go to App
Go to App

Learning Materials

Features

Discover

Chapter 15: Problem 307

Write balanced equations for the preparation of each of the following organometallic compounds by two different reactions starting from suitable alky1 halides and inorganic reagents. Specify reaction conditions and solvents. In each case, indicate which method of preparation you would prefer from standpoints of yield, convenience, etc. (a) \(\left(\mathrm{CH}_{3}\right)_{2} \mathrm{Zn}\) (c) \(\left(\mathrm{CH}_{3} \mathrm{CH}_{2}\right)_{4} \mathrm{~Pb}\) (b) \(\mathrm{CH}_{3} \mathrm{MgCl}\) (d) \(\left(\mathrm{CH}_{3}\right)_{2} \mathrm{CHLi}\)

Short Answer

Expert verified
In summary, the preferred methods for preparing the desired organometallic compounds are as follows: (a) (CH3)2Zn: Method 1 - Reaction of Zinc powder with two methyliodides (b) CH3MgCl: Method 1 - Grignard reaction (c) (CH3CH2)4Pb: Method 1 - Direct synthesis (d) (CH3)2CHLi: Method 1 - Lithium-halogen exchange reaction

Step by step solution

01

Method 1: Reaction of Zinc powder with two methyliodides

To prepare the dimethylzinc from zinc powder, you can react the zinc powder with two methyliodides. The balanced equation for this reaction is: \[Zn + 2CH_{3}I \rightarrow (CH_{3})_{2}Zn + I_{2}\] This reaction occurs at room temperature in a dry non-polar solvent like diethyl ether.
02

Method 2: Transmetallation reaction between diethylzinc and methyl iodide

An alternative way to prepare dimethylzinc is by using a transmetallation reaction between diethylzinc and methyl iodide. The balanced equation is: \[(C_{2}H_{5})_{2}Zn + CH_{3}I \rightarrow (CH_{3})(C_{2}H_{5})Zn + C_{2}H_{5}I\] Then, you can react the above product with another methyl iodide: \[(CH_{3})(C_{2}H_{5})Zn + CH_{3}I \rightarrow (CH_{3})_{2}Zn + (C_{2}H_{5})I\] These reactions will take place in a dry non-polar solvent like diethyl ether at room temperature.
03

Preferred method

The preferred method to prepare (CH3)2Zn is Method 1 because it directly yields the desired product and does not require multiple reactions. ##(b) Preparation of CH3MgCl##
04

Method 1: Grignard reaction

To prepare CH3MgCl, you can start with a Grignard reaction. React magnesium metal with methyl chloride in a dry, non-polar solvent such as diethyl ether or tetrahydrofuran. The balanced equation is: \[Mg + CH_{3}Cl \rightarrow CH_{3}MgCl\]
05

Method 2: Halogen-metal exchange reaction

An alternative method for the synthesis of CH3MgCl is the halogen-metal exchange reaction. The reaction occurs between isopropylmagnesium chloride and methyl iodide. The balanced equation is: \[(CH_{3})_{2}CHMgCl + CH_{3}I \rightarrow (CH_{3})_{2}CHI + CH_{3}MgCl\] The reaction takes place in a dry non-polar solvent like diethyl ether or tetrahydrofuran at low temperatures, between -20°C and -78°C.
06

Preferred method

The preferred method for the preparation of CH3MgCl is Method 1 because it is a direct and straightforward process. ##(c) Preparation of (CH3CH2)4Pb##
07

Method 1: Direct synthesis

Tetraethyllead can be prepared by the direct reaction of lead with four ethyl halides. The balanced equation for this reaction is: \[Pb + 4(CH_{3}CH_{2}I) \rightarrow (CH_{3}CH_{2})_{4}Pb + 4I\] This reaction occurs at room temperature in a dry non-polar solvent like diethyl ether.
08

Method 2: Stepwise synthesis

Alternatively, you can first synthesize diethyllead by reacting lead with two ethyl halides: \[Pb + 2(CH_{3}CH_{2}I) \rightarrow (CH_{3}CH_{2})_{2}Pb + 2I\] Then, you can react diethyllead with two more ethyl halides to form tetraethyllead: \[(CH_{3}CH_{2})_{2}Pb + 2(CH_{3}CH_{2}I) \rightarrow (CH_{3}CH_{2})_{4}Pb + 2I\] These reactions take place in a dry non-polar solvent like diethyl ether at room temperature.
09

Preferred method

The preferred method for preparing (CH3CH2)4Pb is Method 1, as it is direct and less time-consuming. ##(d) Preparation of (CH3)2CHLi##
10

Method 1: Lithium-halogen exchange reaction

You can prepare (CH3)2CHLi using a lithium-halogen exchange reaction. React isopropyl bromide with n-butyllithium, followed by the addition of HCl at low temperatures. The balanced equation is: \[(CH_{3})_{2}CHBr + BuLi \rightarrow (CH_{3})_{2}CHLi + BuBr\] This reaction occurs in a dry non-polar solvent like diethyl ether at low temperatures, between -20°C and -78°C.
11

Method 2: Halogen-metal exchange reaction using Grignard reagent

Another method is to use a Grignard reagent, such as isopropyl magnesium chloride, and react it with lithium chloride. The reaction is represented as: \[(CH_{3})_{2}CHMgCl + LiCl \rightarrow (CH_{3})_{2}CHLi + MgCl_{2}\] The reaction takes place in a dry, non-polar solvent like diethyl ether or tetrahydrofuran at low temperatures, between -20°C and -78°C.
12

Preferred method

The preferred method for the synthesis of (CH3)2CHLi is Method 1 due to its directness and fewer reagent requirements.

Unlock Step-by-Step Solutions & Ace Your Exams!

  • Full Textbook Solutions

    Get detailed explanations and key concepts

  • Unlimited Al creation

    Al flashcards, explanations, exams and more...

  • Ads-free access

    To over 500 millions flashcards

  • Money-back guarantee

    We refund you if you fail your exam.

Start your free trial

Over 30 million students worldwide already upgrade their learning with Vaia!

One App. One Place for Learning.

All the tools & learning materials you need for study success - in one app.

Get started for free

Most popular questions from this chapter

Propose a synthesis for n-butane from n-butylbromide using the Grignard Reaction.

The following experimental observations have been reported: [1]) t-Buty1 chloride was added to lithium metal in dry ether at \(35^{\circ}\). A vigorous reaction ensued with evolution of hydrocarbon gases. After all the lithium metal was cosumed, the mixture was poured onto Dry Ice. The only acidic product which could be isolated (small yield) was 4,4 -dimethylpentanoic acid. 2) t-Buty1 chloride was added to lithium metal in dry ether at \(-40^{\circ}\). After all the lithium had reacted, the mixture was carbonated and gave a good yield of trimethylacetic acid. 3) t-Buty1 chloride was added to lithium metal in dry ether at \(-40^{\circ}\). After all the lithium was gone, ethylene was bubbled through the mixture at \(-40^{\circ}\) until no further reaction occurred. Carbonation of this mixture gave a good yield of 4, 4 -dimethylpentanoic acid. a) Give a reasonably detailed analysis of the results obtained and show as best you can the mechanisms involved in each reaction. b) Would similar behavior be expected with methy1 chloride? Explain. (c) Would you expect that any substantial amount of \(6,6-\) dimethytheptanoic acid would be found in (3) (above)? Explain.

Write structures for the products of the following reactions involving Grignard reagents. Show the structures of both the intermediate substances and the substances obtained after hydrolysis with dilute acid. Unless otherwise specified, assume that sufficient Grignard reagent is used to cause those reactions to go to completion which occur readily at room temperatures. (a) \(\mathrm{C}_{6} \mathrm{H}_{5} \mathrm{MgBr}+\mathrm{C}_{6} \mathrm{H}_{5} \mathrm{CHO}\) (b) \(\mathrm{CH}_{3} \mathrm{MgI}+\mathrm{CH}_{3} \mathrm{CH}_{2} \mathrm{CO}_{2} \mathrm{C}_{2} \mathrm{H}_{5}\) (c) \(\left(\mathrm{CH}_{3}\right)_{3} \mathrm{CMgCl}+\mathrm{CO}_{2}\) (d) \(\mathrm{CH}_{3} \mathrm{CH}_{2} \mathrm{MgBr}+\mathrm{ClCO}_{2} \mathrm{C}_{2} \mathrm{H}_{5}\) (e) \(\mathrm{CH}_{3} \mathrm{Mg} 1+\mathrm{CH}_{3} \mathrm{COCH}_{2} \mathrm{CH}_{2} \mathrm{CO}_{2} \mathrm{C}_{2} \mathrm{H}_{5}\) \((1\) mole \()\) \((1\) mole \()\) 0

When \(10.0 \mathrm{~g}\) of n-propylchloride is allowed to react with excess sodium in the Wurtz reaction, how many grams of hexane would be produced assuming a \(70 \%\) yield?

What products would you expect to be formed in an attempt to synthesize hexamethylethane from t-buty1 chloride and sodium? Write equations for the reactions involved.
See all solutions

Recommended explanations on Chemistry Textbooks

Chemical Reactions

Read Explanation

Physical Chemistry

Read Explanation

The Earths Atmosphere

Read Explanation

Inorganic Chemistry

Read Explanation

Making Measurements

Read Explanation

Nuclear Chemistry

Read Explanation
View all explanations

What do you think about this solution?

We value your feedback to improve our textbook solutions.

Study anywhere. Anytime. Across all devices.

Sign-up for free