A hydrocarbyldithiomethyl-modified compound of the Formula: R.sup.1--O--CH.sub.2--S--S--R.sup.2 or a salt thereof wherein R.sup.1 is an organic molecule and R.sup.2 is a hydrocarbyl is useful for protecting and/or blocking hydroxyl groups in organic molecules such as nucleotides. The hydrocarbyldithiomethyl-modified compounds can also be used for chemically synthesizing oligonucleotides and for sequencing nucleic acid compounds.