Laboratory Methods of Inorganic Chemistry, 2nd English Ed. 1928

216 METAL-ORGANIC COMPOUNDS.

Lead Tetraphenyl. Place 70 g. of perfectly dry ether, which

has stood several days in contact with sodium wire, and 25 g. of

brombenzene in a small flask. Add 3.7 g. of magnesium ribbon

which has been scraped clean with a knife, close the flask with a

calcium chloride tube and allow it to stand 24 hours in a dish of

water. When all the magnesium has dissolved, add, while

shaking, 24 g. of dry powdered lead chloride in small portions,

and allow the mixture to stand for two days with occasional

shaking. Then add this mixture, a little at a time, to 200 c.c. of

water and acidify faintly with dilute hydrochloric acid. Collect

the precipitate (which is colored dark by precipitated lead) on a

suction filter, wash it with water, and dry it in the hot closet.

The mass becomes lighter colored on drying and weighs about

15 g. Boil the material with two successive portions of 100 c.c.

each of benzene, using a reflux condenser, and concentrate the

combined filtrates in a distilling apparatus^1 to about 75 c.c. Color-

less, glistening prisms, melting-point 222° to 224°, crystallize from

the liquid. Yield, 8 to 9 g.

Further concentration of the mother-liquid furnishes but little

additional product.

Diphenyl-lead-iodide. (CeHb) 2 Pbl 2.

Two of the phenyl groups in lead tetraphenyl can be replaced with

hydroxyl groups, or with acid radicals:

Pb(C 6 H 5 ) 4 + 2 I 2 = (C 6 H 6 ) 2 PbI 2 + 2 C 6 H 6 I.

Dissolve 3 g. of lead tetraphenyl by warming it with 60 g. of

chloroform. After cooling add carefully a cold solution of 3 g.

iodine in a little carbon disulphide until the color of the iodine

just fails to disappear. Allow the yellow solution to evaporate

in a warm place; extract the residue first with 10 c.c. and then

with 5 cc. of carbon disulphide; concentrate
2
the filtered extract

to a volume of between 5 and 10 c.c; and allow it to crystal-
lize, after the addition of 2 to 3 c.c. of absolute alcohol. Drain

(^1) Benzene vapors are inflammable and burn with a smoky flame.

• Small quantities of carbon bisulphide and other inflammable liquids can
  be evaporated over a free flame in an open vessel if the vapors are drawn
  rapidly away through a tube connected with the suction pump. The tube
  should be inserted about one-third the way into the beaker or flask.