If a person makes divorce conditional upon something, then he does that thing by mistake or because he is forced to
Question

                I intended that if I did a certain thing, my wife would be divorced with the actual intention of divorce. If I do this thing under compulsion, does divorce take place? If I do this thing repeatedly, does divorce take place each time?.
Praise be to Allah.
    If the matter is limited to the mere intention of divorce, 
    and it was not spoken out loud, then no divorce takes place. 

    Ibn Qudaamah (may Allaah have mercy on him) said (7/373): 
    Divorce does not take place unless the word of divorce is uttered, except in 
    two cases: the first of which is that of a person who is not able to speak, 
    such as a mute, if he divorces by means of gestures, in which case his wife 
    is divorced. This is the view of Maalik, al-Shaafa’i and ashaab al-ra’y, and 
    we do not know of anyone who disagreed with them. The second case is if he 
    wrote the word of divorce. If he intended it as such, then his wife is 
    divorced. This is the view of al-Sha’bi, al-Nakha’i, al-Zuhri, al-Hakam, Abu 
    Haneefah, Maalik and al-Shaafa’i. End quote. 

    But if you uttered the word of divorce and made it 
    conditional upon doing a specific thing with the intention of divorce, then 
    divorce takes place when that thing is done, unless you did it as the result 
    of forgetfulness or because you were forced to do it, in which case divorce 
    does not take place. 

    Ibn Hajar al-Haytami said in al-Fataawa al-Fiqhiyyah 
    al-Kubra (4/178): If a person swears an oath to divorce or do something 
    else if he does  a certain thing, then he does it by mistake, forgetting 
    that condition, or he remembers it but is forced to do that thing, or he 
    chooses to do it due to ignorance of the condition but not the ruling, then 
    he has not broken his oath, because of the report mentioned above (“Allaah 
    has forgiven my ummah for mistakes, forgetfulness and what they are forced 
    to do”). In other words, He will not call them to account for any of these 
    three things, so long as there is no evidence to the contrary such as 
    compensation for damaged property. Doing the action in these cases is like 
    not doing it. End quote. 

    If what you mean by compulsion is that you were forced to do 
    that action, then divorce has not taken place, but if you are not forced to 
    do it, then divorce has taken place. 

    If divorce did not take place because of forgetfulness or 
    compulsion, then the conditional divorce remains as is, and if you do that 
    thing later on, then divorce will have taken place. 

    But does divorce take place every time you do it? That 
    depends on the wording that you uttered. If you said, “If I do such and such 
    my wife is divorced,” then divorce has taken place only once. But if you 
    said: “Every time I do such and such, my wife is divorced,” then divorce is 
    repeated when the action is repeated. 

    But if you did not say anything and it was only a matter of 
    intention, then no divorce has taken place at all, as stated above. 

    And Allaah knows best.