TECHNOLOGY FOCUS - ORGANIC CHEMISTRY - Preferred Component: The glycol diether is a dimer, trimer, or oligomer, preferably diethylene glycol dibutyl ether.Preferred Properties: The glycol diether has a normal boiling point of at least 100 (preferably at least 200)degreesC, and a viscosity of not greater than 3000 (preferably not greater than 2000) mm2/s at 25degreesC. The mole ratio of lithium aluminum hydride to the substituted silacycloalkane is 0.5-3, preferably 0.5-1.2. The mole ratio of the glycol diether to the substituted silacycloalkane is 0.3-5, preferably 1-3.Preferred Method: The rate of addition of the substituted silacycloalkane to the suspension of lithium aluminum hydride in the glycol diether is slow to minimize distillation of the substituted silacycloalkane from the reaction mixture. It is such that the distillate contains less than 20% (preferably less than 10%) (gas chromatography (GC) area%) of the substituted silacycloalkane. The distilling step is carried out at a pressure of 0.1-20 kPa and at -20 to 25degreesC. The adding and distilling steps are carried out in sequential order, or simultaneously. Preferred Definition:    X1, X2 = -Cl;    R1 = 1-4C hydrocarbyl; and    n = 1.    EXAMPLE - Lithium aluminum hydride powder (100 g, 2.63 mol) and diethylene glycol dibutyl ether (984 g, 4.51 mol) were combined under argon in a 2L three-neck flask equipped with a mechanical stirrer, addition funnel, and a three-way adapter connected to a thermometer, vacuum adapter, and multi-flask receiver assembly. The temperature of the mixture was adjusted to 0degreesC and then the pressure was reduced to about 1 mmHg (133 Pa). While maintaining the temperature at 0degreesC, 1,1-dichloro-1-silacyclobutane (298 g, 2.11 mol) was added drop wise to the mixture over a period of 2.5 hours, during which time the product was continuously removed by distillation. After the addition was complete, an empty receiving flask was rotated into position, 1,1-dichloro-1-silacyclobutane (91 g, 0.65 mol) was again added drop wise to the reaction mixture, and the product was continuously removed by distillation. In a similar manner, a third portion of 1,1-dichloro-1-silacyclobutane (120 g, 0.851 mol) and a fourth portion of 1,1-dichloro-1-silacyclobutane (65 g, 0.46 mol) were sequentially added to the reaction mixture. The product formed during each addition was continuously removed by distillation and collected in a fresh receiving flask.    The product (146.3 g) from the first addition of 1,1-dichloro-1-silacacylcobutane consisted of silacyclobutane (97.4 GC area %) and 1,1-dichloro-1-silacyclobutane (1.1 GC area %).    The product (43.4 g) from the second addition of 1,1-dichloro-1-silacacylcobutane consisted of silacyclobutane (92.3 GC area %) and 1,1-dichloro-1-silacyclobutane (7.6 GC area %).    The product from the third addition (59.1 g) and the product from the fourth addition (33.1 g) of 1,1-dichloro-1-silacacylcobutane were combined to afford a crude product consisting of silacyclobutane (93.3 GC area %) and 1,1-dichloro-1-silacyclobutane (6.6 GC area %).    All the products were combined and fractionally distilled in vacuo to give silacyclobutane (99.6 GC area %) as a colorless liquid having a boiling point of about 7degreesC. at 170 mmHg (22.7 kPa).