important

*The first years of school are important for a child to learn certain kinds of behavior.

You can say, with somewhat different meaning (or focus):

1) The first years of school are important for a child because (then) he learns certain kinds of behavior.

2) It is important for the child to learn certain kinds of behavior in/during the first years of school.

1) was probably the intended meaning here. But why is the sentence above unacceptable?

The answer is that different adjectives allow differents types of complementation. Quirk et al. (§16.75) distinguish seven types of constructions composed of an adjective followed (complemented) by an infinitive clause:

1. Bob is splendid to wait.
2. Bob is slow to react.
3. Bob is sorry to hear it.
4. Bob is hesitant to agree with you.
5. Bob is hard to convince.
6. The food is ready to eat.
7. It is important to be accurate.

a. includes adjectives that are evaluative of human behavior and can be transformed into this pattern (careful, careless, crazy, greedy, mad, nice silly, wise, unwise, wrong):

It is splendid of Bob to wait.

b. includes adjectives that can become adverbs and allow the infinitive to become the finite verb:

Bob reacts slowly.

c. includes emotive adjectives, and the infinitive expresses causation (afraid, angry, ashamed, content, furious, glad, happy, impatient, indignant, jublilant, thankful, annoyed, astonished, bored, concerned, delighted, depressed, disappointed, disgusted, dissatisfied, embarrassed, fascinated, frightened, interested, overjoyed, overwhelmed, perturbed, puzzled, relieved surprised, worried):

Bob is sorry because he (has) heard it.

To hear it makes Bob sorry.

d. includes adjectives that express volitional, ability, possibility, or liability (able, anxious, apt, certain**, curious, due, eager, eligible, fit*, free*, greedy, hesitant, impotent, keen liable, likely**, loath, powerless, prone, ready*, reluctant, sure**, unable, welcome, willing, worthy, determined, disposed fated**, inclined, poised, prepared, [all] set, unqualified). Those marked ** can be transformed in sentences like (extraposed that-clauses):

It is likely that Jill will attend.

Those marked * can become infinitive constructions with passive meaning:

Those apples are not fit to be eaten.

e. includes adjectives related to the subject of the sentence and, at the same time, to the unexpressed object of the infinitive (awkward, convenient, difficult, easy, hard, impossible, nice, pleasant, tought, tricky, unpleasant):

Bob [subject] is hard to convince.

To convince Bob [object] is hard.

It is hard to convince Bob [object].

f. includes adjectives that are like e., except that the transformation with an infinitive clause subject is not possible (available, fit, free, ready, sufficient), but a passive infinitive usually is, without change of meaning:

The food is ready to eat.

*To eat the food is ready.

The food is ready to be eaten.

Some of these adjectives can also be Type d., so a sentence like The lamb is ready to be eaten is ambiguous.

g. includes adjectives that derive from underlying constructions with the infinitive as grammatical subject (important, vital, strange, essential, appropriate, compulsory, crucial, fitting, imperative, possible, necessary, obligatory, proper, advisable, desirable, preferable):

To be accurate is important.

The infinitive can also for introduced by for + subject:

It is important for people/us/everyone, etc. to be accurate.

So, finally, returning to our original problem sentence, we can say that important, like the other adjectives of Type g., simply does not allow this type of construction.