Diethylzinc CAS 557-20-0

This method directly generates diethylzine through the oxidation-reduction reaction between halogenated ethane (such as iodoethane, bromoethane) and activated zinc powder. The reaction formula is:
2 C₂H₅X + Zn → (C₂H₅)₂Zn + ZnX₂
Among them, X represents a halogen atom (I, Br). During the reaction process, electron transfer on the surface of zinc powder promotes the breaking of carbon halogen bonds in halogenated hydrocarbons, forming carbon zinc bonds and ultimately producing the target product.

Zinc powder pretreatment
Equipment: 1000mL glass bottle with bottom tube
Operation: Add 600g of zinc powder (6N grade), introduce dry hydrogen gas to slightly bubble the tail gas cylinder, slowly raise the temperature to 200 ℃ and hold for 30 minutes, observe the condensation of water vapor on the tail gas tube wall, confirm the removal of the oxide layer, and then cool down to room temperature.
Objective: To remove the surface oxide layer of zinc powder, expose active sites, and improve reaction efficiency.

Construction of Inert Environment
Equipment: 1000mL four necked glass flask (equipped with spherical condenser tube, constant pressure funnel, thermometer sleeve, stainless steel stirrer)
Operation: Connect the nitrogen system, fill it with nitrogen and replace it 3 times to ensure that the oxygen content in the reaction system is below 0.1ppm.

Reaction initiation and temperature control
Operation:
Add pre treated zinc powder and sequentially drip 10mL of iodoethane/bromoethane mixed solution (volume ratio 1:1), 10g of cuprous iodide (catalyst), and 30g of diethylzinc (initiator).
When the temperature rises to 58-60 ℃, reflux accelerates. After heating to 80 ℃, the remaining mixed solution is added. After the solution is added, it is heated to 140 ℃ and kept at that temperature for 1 hour.

Key points:
The triggering stage requires strict temperature control to avoid local overheating and side reactions;
Copper iodide can reduce the activation energy of the reaction and shorten the initiation time (usually<40 minutes);
The staged heating strategy can balance the reaction rate and product purity.
Product separation and purification

Operation:
When naturally cooled to 70 ℃, the material solidifies. After complete cooling, connect the low-temperature receiving device (receiving bottle temperature<-35 ℃).
Vacuum distillation (pressure -0.08 to -0.09MPa) is used to collect gas phase temperature fractions at 30-50 ℃, and secondary distillation is used to collect mixtures at 50-60 ℃.
Purity index: Diethyl zinc purity ≥ 99.9%, zinc impurity concentration ≤ 10ppm, lead impurity concentration ≤ 1ppm.

When a certain enterprise adopts a 500L reaction kettle for large-scale production, it achieves a 30% increase in annual production capacity through the following improvements:

Raw material pre mixing: pre mix iodoethane and bromoethane in a ratio of 1:1.2 to reduce fluctuations in dropwise addition time;
Gradient heating: Set a three-stage temperature control program of 80 ℃, 120 ℃, and 140 ℃ to shorten the insulation time to 45 minutes;
Continuous distillation: Adopting a two-stage distillation tower series process, the first stage separates unreacted halogenated hydrocarbons, and the second stage purifies diethyl zinc, with a product purity of 99.95%.

Using the double decomposition reaction of alkyl aluminum (such as triethylaluminum) and zinc chloride to generate diethyl zinc, the reaction equation is:
ZnCl₂ + 2 Al(C₂H₅)₃ → (C₂H₅)₂Zn + 2 Al(C₂H₅)₂Cl
This method achieves high selectivity synthesis by controlling the molar ratio of reactants (usually ZnCl ₂: Al (C ₂ H ₅) ∝=1:2.2) and reaction conditions (such as temperature and solvent).

Advantage:
Low raw material cost: the price of triethylaluminum is only 1/5 of iodoethane;
Recyclable by-products: Diethyl aluminum chloride (Al (C ₂ H ₅) ₂ Cl) can be recycled as an alkylating reagent;
High industrial feasibility: mild reaction conditions (from room temperature to 80 ℃), low equipment corrosiveness.

Challenge:
The purity requirements for raw materials are strict: the concentration of hydrides in triethylaluminum needs to be controlled between 0.01-0.10wt%, otherwise precipitation may occur and block the equipment;
The difficulty of product separation is high: the boiling points of diethylzine and diethylaluminum chloride are close (98 ℃ for the former and 150 ℃ for the latter), requiring the use of vacuum distillation or extraction distillation techniques.

Raw material preparation:
Mix triethylaluminum (purity ≥ 99.5%) with white oil (diluent) in a 1:1 volume ratio to reduce the intensity of the reaction;
Zinc chloride (anhydrous grade) is dried at high temperature of 200 ℃ for 4 hours to remove crystal water.

Reaction control:
Under nitrogen protection, slowly add zinc chloride to the triethylaluminum solution, and control the feeding rate so that the temperature does not exceed 60 ℃;
After the reaction is complete, dilute the system with n-hexane (solvent) to reduce viscosity and facilitate separation.

Product separation:
Reduced pressure distillation (pressure -0.095MPa):
Phase 1: Collect 30-50 ℃ fractions (unreacted triethylaluminum);
Phase 2: Collect fractions at 60-150 ℃, where 60-98 ℃ is diethyl zinc and 98-150 ℃ is diethyl aluminum chloride.
Purity verification: Through gas chromatography (GC) detection, the purity of diethylzine is ≥ 99.9%, and the purity of diethylaluminum chloride is ≥ 99.5%.

Utilize the surface catalytic activity of zinc copper alloy (Zn Cu) or zinc sodium alloy (Zn Na) to promote the formation of carbon zinc bonds in halogenated ethane. Taking zinc copper alloy as an example, the reaction equation is:
Zn-Cu + C₂H₅X → C₂H₅ZnX → (C₂H₅)₂Zn + ZnX₂
Copper or sodium in alloys can alter the electronic structure of zinc, reduce reaction activation energy, and increase reaction rate.

Alloy preparation:
Melt and mix zinc powder and copper powder (mass ratio 9:1) in an inert atmosphere, and cast them into a block alloy;
Crush to 200 mesh powder for subsequent reactions.

Reaction optimization:
Temperature control: Gradient heating of 30-150 ℃ to avoid local overheating;
Drop acceleration: The drop acceleration of a mixture solution of iodoethane/bromoethane (volume ratio 1:1) is 2-3mL/min;
Mixing intensity: Magnetic stirring (speed of 500rpm) is used to ensure sufficient dispersion of the alloy powder.

Product purification:
Reduced pressure distillation (pressure -0.1 MPa):
Initial boiling point: Collect<50 ℃ fractions (unreacted halogenated hydrocarbons);
Main fraction: Collect fractions at 50-98 ℃ with a purity of ≥ 99.5%;
Tail fraction:>98 ℃ fraction (high boiling impurities).

A certain enterprise adopts the zinc copper alloy method to construct a production line with an annual output of 10 tons of diethylzinc. The key improvements include:

Continuous preparation of alloy: Design a melting atomization device to achieve continuous production of alloy powder with a particle size distribution D50=150 μ m;
Reactor design: Adopting a fluidized bed reactor to enhance gas-solid phase contact and shorten the reaction time to 4 hours;
Energy saving distillation: Utilizing heat pump technology to recover distillation waste heat, reducing energy consumption by 40%.