From CaGEL p1178
To-infinitivals with and without subject
To-infinitivals with overt subject require the subordinator for
To-infinitivals containing a subject are always introduced by the subordinator for:
i [For them to withdraw now] would be a mistake. [subject]
ii It's not been necessary [for them to wait any longer].
iii The best plan would be [for them to go alone].
iv I can think of no solution except [for them to sack him].
[comp of preposition]
If we drop the for we must also drop the subject, and conversely,
for cannot appear without a following subject. Compare [20ii], for example, with:
i It is not necessary [to wait any longer].
ii * It is not necessary [them to wait any longer].
iii * It is not necessary [for to wait any longer].
Notice, moreover, that the interrogative to-infinitivals shown in
[11i] and the wh- relative [11iia] cannot contain a subject:
i a. I can't decide [whether to go with them]. (=[11ia])
b. * I can't decide [whether (for) us to go with them].
ii a. He doesn't know [how to placate her]. (=[11ib])
b. * He doesn't know [how (for) us to placate her].
iii a. They have funds [with which to conduct a survey].
b. * They have funds [with which (for) us to conduct a
The well-formed examples here all exclude for because the prenuclear
position is occupied - by the interrogative subordinator whether,
the interrogative phrase how, or the relative phrase with which.
And because an infinitival cannot contain a subject unless introduced
by for the asterisked examples here are as bad in the version
without for as in the one where for illicitly appears.
From CaGEL p1222-1223
Adjunct of purpose
In general, infinitival clauses functioning as adjunct of purpose are sharply distinct from catenative complements.
Syntactically, they can be preceded by in order and
characterisically can be moved to front position:
i He walked [(in order) to save money]. [purpose adunct]
ii [(In order) to save money,]he walked. [purpose adjunct]
Semantically, they of course express the purpose of some agentive act
and we accordingly have a very clear ambiguity in:
 He swore to impress his mates. [catenative complement or
The catenative interpretation is "He swore that he would impress his
mates (in some unspecified way)", whereas with an adjunct the meaning
is "He swore in order to impress his mates (by swearing)". In the
adjunct reading, swore receives greater phonological prominence and
in writing is likely to be followed by a comma.
With a few verbs, sch as wait and hurry, the semantic distinction
is at times somewhat blurred - compare:
i. a. She was waiting for his letter to arrive. [catenative
b. She waited a while to make sure he wasn't coming back.
c. She was waiting to use the photocopier.
ii. a. He hurried to reassure her. [catenative complement]
b. He hurried, to prove he wasn't as slow as she claimed.
c. He hurried to catch the train.
With wait the contrast is clear in [ia-ib]: the catenative
complement identifies the event she was waiting for and the adjunct
gives the purpose of her waiting; [ic] can be construed as a
catenative construction, but at the same time there is an element of
purpose. Presumably she couldn't use the photocopier immediately
(someone else was using it or it needed attention), so it was
necessary for her to wait. In [ii] hurry is equivalent to hasten
in [iia], wher the meaning is that he quickly reassured her, or tried
to do so; [iib] is straightforwardly purposive and readily allows in
order and fronting; such fronting is very unlikely in [iii], but it
is probably best treated as also purosive, for we could not here
Go is a borderline member of the catenative category:
i She went to the Old Vic to see 'Hamlet'. [purpose adjunct]
ii She went to see 'Hamlet'. [?catenative complement]
It is quite clear that in [i] the phrase to the Old Vic is a
complement with the role of goal and the infinitival is an adjunct of
purpose. In [ii] (spoken without any prosodic break after went) the
concept of a spatial goal is very much backgrounded and it is not
implausible to regar the infinitival as having been reanalysed as a
complement: we certainly cannot insert in order and do not interpret
it as answering the question Why did she go?