import re,json

def findTokenOffset(text, pattern):
    items = []
    for m in pattern.finditer(text):
        item = {}
        #item['index']= NO!! #// word index starts from 1
        item['word']=m.group()
        item['characterOffsetBegin'] = m.start()
        item['characterOffsetEnd'] = m.end()
        items.append(item)
    return items

text = "George Washington came to Washington Washington.com"
tokens = ["George Washington", "Washington"]
pattern = re.compile(fr'(?<!\w)(?:{"|".join(sorted(map(re.escape, tokens), key=len, reverse=True))})(?!\w)(?!\.\b)', re.I )
offsets = findTokenOffset(text,pattern)
print(json.dumps(offsets, indent=2))