三苯甲醇的合成

Method 1:
Mg
Br MgBr
anhydrous ether
Grignard reagents(格氏试剂) form via the reaction of an alkyl or aryl halide with magnesium metal. The reaction is conducted by adding the organic halide to a suspension of magnesium in an ether solvent(醚类 溶 剂 ), which provides ligands required to stabilize the organomagnesium compound.
3.2 Materials
① bromobenzene （溴苯）（FW 157) 7.85g 5.3mL(0.05mol） ② Anhydrous ether（FW 74） b.p. 34.5 ℃
③ Magnesium turning or ribbon （FW 24.3) 1.4g (0.055mol)
3. Drive out the water, CO2, O2 in the reaction system. RMgX+CO2 = RCOOMgX = RCOOH+Mg（OH）X 2 RMgX + O2 = 2 ROMgX
O
OMgBr
NH4Cl
MgBr
OH
H+, -H2O +H2O
白的沉淀
红色溶液
Add 4-5 mL solution of 5.3 mL bromobenzene in 20 mL of anhydrous ether.
Ether boiling Brownish solution colorless
Add the rest stirring bromobenzene/ether solution Add solution of 9g Warm-water bath(45Cool it in ice30 min Benzophenone in 25 water bath 50 ℃) mL of anhydrous ether. Cool it in iceReflux about 30 min Add 40 mL of Saturated water bath ammonium chloride . Add 20 mL of Distill Ether Vacuum filtrate Petroleum ether. recrystallization Dry Ca. pecentage yield.
⑥ Saturated ammonium chloride solution ⑦ Petroleum ether
4 Procedure实验流程
Add 1.4g magnesium Iodine crystal Warm-water bath(4550 ℃) Remove warmwater bath
Br
MgBr
The rate of addition should be adjusted so that the reflux ring in the water cooled condenser is no more than half way up the inner tube, if the reaction becomes too vigours, the more biphenyl( 联苯 ) by product will formed. The crude product contains the desired triphenylmethanol and also the biphenyl by-product. Most of the biphenyl can be removed by dissolving in the petroleum.(石油醚)
H2O
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Mg(OH)Br
It is critical to maintain completely dry conditions throughout the formation and reaction of the Grignard reagent.
The fuction of anhydrous ether:
CH3 CH2 OCH2CH3
MgBr
CH3 CH2 OCH2CH3
1. Solvent： phenylmagnesium bromide is easily dissolvable in anhydrous ether. 2. Complex was formed by the reaction of phenylmagnesium bromide with ether. To keep the stability of phenylmagnesium bromide.
Method 2:
O O MgBr OMgBr O NH4Cl O
慢
MgBr
OMgBr NH 4Cl
快
OH H +, -H2O +H2O
白的沉淀
红色溶液
3. Apparatus and materials 3.1 stirring apparatus
Mechanical stirrer with a reflux condenser and a droping funnel
Maker sure that all your glassware and reagents are thoroughly dry before conducting the experiment. Grignard reagent is very easily hydrolyzed（水解）.
MgBr
Bright magnesium ribbon can be used instead of magnesium turning. Scrape both side of the ribbon with an abrasive to remove any oxide, cut the ribbon into small pieces.
1.2 Master the techniques of stirring，reflux（回 流），extraction， distillation and recrystallization.
2. Principle
The Grignard reaction is an organometallic chemical reaction in which alkyl （烷基） , vinyl （乙烯基） , or aryl （ 芳 基 ） -magnesium( 镁 ) halides (Grignard reagents) add to a carbonyl group in an aldehyde（醛） or ketone（酮）.This reaction is an important tool for the formation of carbon–carbon bonds. The reaction of an organic halide with magnesium is not a Grignard reaction, but provides a Grignard reagent.
Preparation(Synthesis) and Characterization of Triphenylmethanol （三苯甲醇的合成与表征） 1. Purpose
1.1 Study the principle and method of preparing triphenylmethanol by the Grignard reaction（格林 尼雅反应）.
The role of the saturated ammonium chloride(氯化铵) solution is to decompose the additional product， forming the crude triphenylmethanol.
SIDE-REACTIONS(副反应)
④ Benzophenone （FW 182) 9g (0.05mol） ⑤ Iodine crystal
Add a small crystal of iodine and promote the heterogeneous(混杂的) reaction at the surface of the magnesium sometimes.