This dissertation describes the infinitive structures from a semantic approach, based on verbal periphrases, to a syntactic one, based on the complement and morphological formation of the first verb, in order to assist the Portuguese as a Second/Foreign Language (PSL/PFL) teaching process. For that, we use Corpus Linguistics through the digital platform Linguateca for the random selection of both quantitative and qualitative data that describe this verbal phenomenon. Based on authors such as Almeida (1980), Travaglia (2014), Barroso (1960), Pontes (1973), Fernandes (1983) and Luft (2003), we were able to conceptualize verbal periphrases and their morphosemantic and morphosyntactic dependence, presenting the aspectual and modal values that involve it, and to characterize the different scenarios that produce semantically independent verbs. One hundred and seventy-two verbal structures are divided into two large groups: thirty-six are considered verbal periphrases and one hundred and thirty-six constitute a group in which the verbs do not hold a semantic relationship between each other due to syntactic factors, such as reduced sentences; due to lexical factors, such as crystallized expressions; due to limitations of the research itself, such as forms in disuse; and due to morphological factors, such as the past participle nominal form. Then, we propose a didactic sequence for advanced PSL/PFL students in order to illustrate the transition from the academic discourse of these structures to the pedagogical discourse. We conclude that the Portuguese prominent infinitive structures in our corpus do not hold a semantic independence between verbs and the reasons that lead them to be considered or not as verbal periphrases are more related to the semantic fluctuations of these structures than to syntactic phenomena.