(too long for a comment, hence posted as an answer)
The inability of TeX (and LaTeX, etc) to hyphenate words with accents -- if the accented words were constructed using accenting primitives and if the font encoding is the "original" or "old" TeX encoding -- has been known for a long time.
What to do? You should (a) if at all possible input the accented words directly, e.g., as adiabática
, (b) use any font encoding other than OT1 (which, as you can probably guess, is the original font encoding method), and (c) load the babel
or polyglossia
packages with the appropriate language choices.
The MWE below was compiled using LuaLaTeX; if compiled under pdfLaTeX the first word would not get hyphenated. (That's a different shortcoming...)

\documentclass[a4paper]{article}
\usepackage{ifluatex}
\ifluatex
\usepackage{fontspec}
\else
\usepackage[utf8]{inputenc}
\usepackage[T1]{fontenc}
\fi
\usepackage[portuguese]{babel}
\setlength\textwidth{1mm} % to force the use of every possible hyphenation point
\begin{document}
\noindent
adiabática adiabática
\end{document}
\usepackage[portuguese]{babel}
in your preamble?\usepackage[T1]{fontenc}
to allow hyphenation - see here and here.input
should not make any difference. did you read the links and made sure none of the answers there help? if so, can you give a MWE for your specific case so we can test?cenas
we can't test many things… Just a lead: add\usepackage{lmodern}
, for instance.\documentclass[10pt,a4paper]{book} \usepackage[utf8]{inputenc} \usepackage[T1]{fontenc} \usepackage[portuguese]{babel} \begin{document} adiabática adiabática adiabática adiabática adiabática adiabática adiabática adiabática adiabática adiabática adiabática adiabática adiabática adiabática adiabática adiabática adiabática adiabática \end{document}