Olá! Espero que estas informações sejam úteis: 1) "si" é um pronome pessoal caso oblíquo e pertence à terceiras pessoa no singular e no plural (ele/ela/eles/elas). Exemplos: "[Ele] vive cheio de si", "[Eles] caíram em si". 2) É interessante notar que no Brasil o pronome "si" é usado, na grande maioria das vezes, como indicador de processo reflexivo. Exemplos: "Ela só pensa em si", "Acertaram entre si as datas". 3) Em Portugal é muito comum o emprego de "si" em relação à pessoa com quem se fala. Exemplo: "Gosto muito de si". SEUS EXEMPLOS: "Isto é para ele" -> this is to him "isto é para si" -> "This is to him" (most commom in Brazil) or "This is to you" (most commom in Portugal) ... But both can be used in both countries

correto é para ele/ela . verifiquei no livro de gramatica o "si" é um pronome reflexivo. neste caso não se utiliza.

The same thing happens with the 2nd and 3rd persons of the plural. 2nd person is vós but in portuguese this is seldom used, we use mostly vocês, so vós = você = you .The problem is that when we use vós we have to conjugate the verb using the 2nd person plural but if we use vocês we conjugate the 3rd person plural. Vós comeis a sopa = Vocês comem a sopa = You eat the soup. Notice please that we also say Eles/Elas comem a sopa. They eat the soup. Regarding the personal pronouns we have two different situations: when they are used as the subject of the sentence or when they are a complement, the first are called pronomes pessoais reto and the latter are called pronomes pessoais oblíquos. For example : Ele tem uma camisola. He has a shirt. Ele is the subject, so it is a pronome pessoal reto 3rd person singular. Eu dei-lhe a camisola (European portuguese ). Eu lhe dei a camisola (Brazilian portuguese ). I gave him the shirt. Now lhe is the personal pronoun that means to him and in this sentence has the function of indirect complement. So we say this is pronome pessoal oblíquo. In this case there is also another specification which is pronome pessoal oblíquo átono, átono means that the pronoun must be placed together with the verb. Dei-lhe= eu dei a ele = I gave him.

Some other examples are. Ela é cheia de si = She is full of herself. The example used above Ele só faz mal para si mesmo = He only make a harm for himself. Ele não cabe em si de contente = literally He doesn't fit in himself of happiness which means that he is soooooo soooooo happy that he can do anything. Notice please the one thing in common in all of these sentences: the pronoum si is always accompanied by the pronoum ele/ela. Now I say Ele não está em si = He is not himself as he doesn't seem like himself. But now I want to say that you don't seem like yourself so I say Tu não está em ti. Si= personal pronoun 3rd person singular in the form oblíquo tónico Ti = personal pronoun 2nd person singular in the form oblíquo tónico. But a Brazilian would say Você não está em si (remember what I said before in Portugal it is uses Tu and in Brazil it is used Você), Você uses the verb conjugated in the 3rd person singular and so it uses also the personal pronoun in the 3rd person plural Você não está em si. But in truth si in this sentence doesn't refer to a she or a he but it refers to a you. So here si means you although it is the form that corresponds to the third person when you consult a book of grammar. Remember again that in Portugal the same sentence Você não está em si would be used in a formal and polite context. So to conclude : if you want to ask is this for you? You can ask Isto é para ti (European portuguese ), isto é para você (Brazilian portuguese ) or isto é para si (formal European portuguese ). If you want to ask is this for him /her you have to say isto é para ele/ela. You DON'T say isto é para si when you mean for him /her . I hope I helped!

Ele comprou a camisola a si mesmo. He bought the shirt for himself. Here si is the personal pronoun 3rd person singular in the form oblíquo tónico. Again oblíquo means it functions as a complement and tónico means it does not have to be next to the verb. But the thing is the pronoun si in this sentence means for himself because it is followed by the word mesmo "si mesmo"=himself. There's also "si próprio" = himself. We can also omitt the pronoun and just write "Ele comprou a camisola" but if we do this then we don't know whom he bought the shirt for. So si in this context informs the person whom he bought the shirt for, for himself and the word mesmo reinforces the idea.