Apple cider vinegar is touted as a "superfood" with seemingly miraculous weightloss and detoxification properties. While most of these claims are surely exaggerated, some of them seem to be factual - some links:
This Australian documentary features research that the acetic acid contained in vinegar helps alleviate autoimmune disorders:
https://www.youtube.com/watch?v=CfDpM9D_if4
A Swedish study has found that vinegar decreases the GI of subsequently consumed food and increases insulin sensitivity, both of which result in increased satiety: http://www.nutraingredients.com/Research/Vinegar-may-help-dieters-eat-less Once more, acetic acid and not some obscure phytonutrient seems the cause.
From personal experience, I can at least attest to the prolonged satiety: For some time, I have been following an intermittent fasting eating pattern, and the long fasting window (usually 16-18 hours) has sometimes been a problem for me. This week, I drank a glass of water with 3 tbsp of vinegar (through a straw to protect my teeth) shortly before the two main meals every day, and I have not experienced any hunger during the fasting window since. Now I'm even thinking about having only one meal a day (but that would probably result in eating too much at one time; I might have to resort to higher calorie density foods which would negate the intended health benefits).
Still, if recurring hunger is a problem for you and you neither want to increase calorie intake nor decrease caloric density, vinegar might be worth a shot.