First and foremost, I would recommend visiting the following website:
The above website clearly defines the differences between shelf-life and expiration life. Although this source applies this concept to primarily aqueous standards, this practice is in fact expandable to almost all applications.
From our research on this very topic, we have found, regardless of the vendor or manufacturer, that any container/item/product lacking a stated expiration date has a SHELF-LIFE that is considered INDEFINITE. Do note, shelf life is NOT synonymous with expiration date (read the information in the above link to appreciate the difference between the two).
Companies like EMD, Fisher, Avantor, Sigma Aldrich, etc. do not state that the SHELF-LIFE of unlabled chemicals is 5 years BUT they do recommend that a 5 year EXPIRATION DATE be given to all containers from the date opened as EXPIRATION DATES do take into account the risk of contamination through human error.
To my knowledge of industry practice, any and all STANDARDS are given a 1 year expiration date at most due to the risk of human contamination from the date of opening. If your high purity solvents and acids are to essentially be considered as a standard, then these should be given a 1 year expiration date.
Again, keep in mind that the shelf-life (stability) of a reagent may surpass its necessary expiration date soely due to the risk of contamination and the affect of contamination on the intended purpose of the reagent.
Nothing should ever exceed a five year expiration date due to the nearly exponential increased risk of contamination as time progresses. It is always acceptable to err on the side of caution if contamination is considered highly likely. If your lab fears likely contamination before 5 years, then an expiration date of perhaps 3 years from opening could be suitable.
For reagents where an expiration date is provided by the manufacturer, obviously follow that expiration date. It is also important to know of expiration dating exceptions for your lab. Reagents such as THF may have an UNOPENED shelf life of perhaps three years from time of manufacture but may exceed manufacture degradation limits within a year of opening regardless of human contamination. For such cases, err on the side of caution with expiration dates that remain within degredation limits. However, a listed manufacturer's expiration date is nearly always sufficient to ensure stability throughout.
As "riverbrat" points out, essentially take the soonest expiration date of any precursor reagent or intermediate as the longest expiration date for a prepared SOLUTION. Also, our auditor inspections as well have resulted in the accepted verbiage that an expired STANDARD could be used only if validation methods were in place to prove its integrity still fell within the standard's original limits prior to every usage beyond expiration. This was not the case with reagents because the statistical probability of contamination was unacceptably high for pharma work in excess of 5 years.
Best of luck