zoology - Why are (some) cats attracted by bleach?

I can't give a definite answer, and there's nothing in the literature about this specifically, but perhaps some relevant information and a suggested behavioural experiment will help.

Background
Firstly, I assume you are talking about sodium hypochlorite (which is usually what people mean by bleach)? If so, there are several compounds your cat could be reacting to. Chlorine is an obvious candidate, which is released as sodium hypochlorite decomposes in solution. Additionally, bleach can react with various organic materials to release a variety of volatile organic compounds (VOCs), which your cat might be able to smell. In addition to also releasing chlorine gas, the same suite of VOCs are released when the chlorine in chlorinated tap water reacts with organic contaminants (Odabasi, 2008). The VOCs include chloroform and carbon tetrachloride.

Next, cats are known to exhibit modified behaviour in response to a variety of compounds. Some are suspected pheromone components of cat urine, such as felinine (Hendriks et al, 1995) and its breakdown products, such as MMB (Miyazaki et. al, 2006).

Some cats also react to externally-produced compounds with a particular response called the 'catnip response', which involves rubbing the face on the ground or other objects, shaking the head, rolling, etc. (Tucker & Tucker, 1988). Not all cats exhibit the response, around 50-50% do, and susceptibility is genetic and heritable. Some sources eliciting the catnip response include:

nepetalactone released from catnip (Nepeta cataria)

actinidine released from valerian (Valeriana officinalis)

essential oil of Actinidia macrosperma (Zhao et al., 2006)

the compounds epinepetalactone, dihydronepetalactone, isodihydronepetalactone, neonepetalactone, iridomyrmecin, boschnialactone, onikulactone, boschniakine, actinidiolide and dihydroactinidiolide (Tucker & Tucker, 1988)

In general all the catnip response elicitors share a two-ring structure, which is not to my knowledge shared by any of the volatiles given off by bleach.

A possible experiment
So, two obvious possibilities (regarding what type of behavioural response is being elicited) are that either:

your cat is interpreting the volatile as a pheremone and therefore as some sort of sexual or territorial signal, or

it is showing the catnip response

As a first experiment, you could check whether your cat (and any others you can get hold of - in an ethical way) respond to bleach and/or to catnip. If the cats do not exhibit the catnip response to catnip, they aren't exhibiting it in response to bleach, and thus some other explanation is more likely.

As a second experiment, you could make a detailed observation of the precise behaviour shown in response to bleach. Compare it to that exhibited when the cats encounter catnip (depending on the outcome of the first experiment) and when they are oestrous (if female) or encounter an oestrous female (if male). You could also compare to the response to the urine of other (male and female, familiar and unfamiliar) cats.

An experiment you shouldn't do
If you wanted to find out which chemical your cat is responding to, you could allow your cat to sniff pure chlorine which hasn't encountered organic contaminants, as well as chloroform, and carbon tetrachloride. However, all three of those compounds are extremely dangerous and could easily kill you or your cat, so please don't.

I general, I would caution against exposing your cat to bleach, because it can induce serious health effects depending on dose and mode of exposure, ranging from asthma to third-degree burns to carcinogenesis. If they are attracted to it, that is a good reason to keep it away from them to prevent them ingesting it, which is more harmful than inhaling the fumes.

I can't comment on whether the behaviour is acquired as result of domestication, but that too could be tested by comparing the reaction of a large sample of wild cats (!).

References