Organopolysiloxane compound having ethynyl groups, method for preparing linear organopolysiloxane compound having ethynyl groups at both terminals of molecular chain, method for preparing organopolysiloxane polymer having alkoxysilyl-ethylene group at terminal, room temperature curable composition and molded product which is cured product thereof

A method for preparing an organosiloxane polymer having an alkoxysilyl-ethylene group at its terminal which comprises subjecting an organopolysiloxane compound which is either a linear or a branched, and having at least one unit of the following formula (1′) as a partial structure and an alkoxysilane to addition reaction according to the following reaction formula, to prepare an organosiloxane polymer which is either a linear or a branched, and having an alkoxysilyl-ethylene group at its terminal having at least one unit of the following formula (1″) in a molecule,

• wherein R represents a hydrogen atom or a monovalent hydrocarbon group having 1 to 20 carbon atoms which may have a substituent;
• each R may be the same or different from each other;
• “m′” represents an integer of 0 to 2,000, parts of a repeating unit of the siloxane bond may be crosslinked to form a branched chain structure;
• “n” represents an integer of 0 to 20;
• R1 represents an alkyl group having 1 to 20 carbon atoms which may have a substituent, and those having 3 or more carbon atoms among the alkyl groups may be a cycloalkyl group which is cyclic;
• R2 represents a hydrogen atom or a monovalent hydrocarbon group having 1 to 20 carbon atoms which may have a substituent;
• and “a” represents an integer of 1 to 3.