request vs ask for

request is a noun but ask for is not a noun.

Word	Noun	Adjective	Verb	Adverb
request	Yes	No	Yes	No
ask for	No	No	Yes	No

As verbs, request and ask for are synonyms defined as:

Other synonyms of request include bespeak, call for, quest.

request (noun)	ask for (noun)
the verbal act of requesting
a formal message requesting something that is submitted to an authority

request (verb)	ask for (verb)
express the need or desire for	express the need or desire for
ask (a person) to do something	increase the likelihood of
inquire for (information)