Can I synthesize an Amide simply by heating an amine and a carboxylic acid (with a vacuum pump)? I am interested in creating an amide of stearic acid. I thought that simply mixing both of them in some solvent, heating the solution, and using a vacuum pump to distill the liberated water (to drive the reaction forward) would be enough.
But a bit of research showed that this synthesis is normally done with acyl chlorides derivatives or methyl ester derivatives or other more elaborate methods.
Without access to those tools, is it still possible for me to produce a good yield of amide, using only a fatty acid, a primary or secondary amine, a solvent, and heating &amp; vacuum?
(Secondary optional question: If I use ethanolamine, what will be formed preferentially, the amino-ester or the hydroxy-amide?)
It can be done but it is not a good reaction. From Lundberg et al. [1]:

Formally, the amide bond is formed through the condensation of a carboxylic acid and an amine with the release of one equivalent of water. This reaction has been considered challenging due to the competing acid–base reaction, which occurs when the amine and the carboxylic acid are mixed. Although the amide bond can be formed from the corresponding ammonium carboxylate salt upon heating, this reaction has generally been considered to be of limited preparative value. Furthermore, the high activation barrier for the direct coupling of a carboxylic acid and an amine can only be overcome using forcing reaction conditions.

Use of borate ester catalysis under Dean–Stark conditions has recently been reported to give good yields without resorting to acyl activation groups [2].
References

Lundberg, H.; Tinnis, F.; Selander, N.; Adolfsson, H. Catalytic Amide Formation from Non-Activated Carboxylic Acids and Amines. Chem. Soc. Rev. 2014, 43 (8), 2714–2742. DOI: 10.1039/C3CS60345H. (PDF)
Sabatini, M. T.; Boulton, L. T.; Sheppard, T. D. Borate Esters: Simple Catalysts for the Sustainable Synthesis of Complex Amides. Sci. Adv. 2017, 3 (9), e1701028. DOI: 10.1126/sciadv.1701028.